SO


Line plots across dimensions of each concept
Tables

Table of contents


us-gaap:StatementEquityComponents
us-gaap:SharesIssued
us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax

us-gaap:Revenues

us-gaap:CostOfGoodsAndServicesSold
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments, dei:LegalEntity
us-gaap:ProductOrService
us-gaap:ProductOrService, dei:LegalEntity

us-gaap:CostsAndExpenses
dei:LegalEntity

us-gaap:OperatingIncomeLoss
dei:LegalEntity

us-gaap:InterestAndDebtExpense
dei:LegalEntity

us-gaap:OtherNonoperatingIncomeExpense
dei:LegalEntity

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
dei:LegalEntity

us-gaap:NonoperatingIncomeExpense
dei:LegalEntity

us-gaap:IncomeTaxExpenseBenefit
dei:LegalEntity

us-gaap:IncomeTaxesPaidNet
dei:LegalEntity

us-gaap:ProfitLoss
dei:LegalEntity

us-gaap:ComprehensiveIncomeNetOfTax
dei:LegalEntity

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
dei:LegalEntity

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic
dei:LegalEntity
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments, dei:LegalEntity
us-gaap:ProductOrService
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest
dei:LegalEntity

us-gaap:Assets
dei:LegalEntity
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, dei:LegalEntity
us-gaap:ConsolidationItems, us-gaap:ProductOrService
us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments, dei:LegalEntity
us-gaap:ProductOrService

us-gaap:Liabilities
dei:LegalEntity
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity

us-gaap:LiabilitiesAndStockholdersEquity
dei:LegalEntity

us-gaap:AssetsCurrent
dei:LegalEntity

us-gaap:CashAndCashEquivalentsAtCarryingValue
dei:LegalEntity

us-gaap:OtherAssetsCurrent
dei:LegalEntity

us-gaap:PropertyPlantAndEquipmentGross
dei:LegalEntity

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
dei:LegalEntity

us-gaap:PropertyPlantAndEquipmentNet
dei:LegalEntity

us-gaap:LongTermInvestments
dei:LegalEntity

us-gaap:Goodwill
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:IntangibleAssetsNetExcludingGoodwill
dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsNet
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsByMajorClass, dei:LegalEntity
dei:LegalEntity
us-gaap:IntangibleAssetsNetIncludingGoodwill

us-gaap:OtherAssetsNoncurrent
dei:LegalEntity

us-gaap:LiabilitiesCurrent
dei:LegalEntity

us-gaap:AccountsPayableCurrent

us-gaap:AccruedIncomeTaxesCurrent
dei:LegalEntity

us-gaap:OtherLiabilitiesCurrent
dei:LegalEntity

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
dei:LegalEntity

us-gaap:OtherLiabilitiesNoncurrent
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInOperatingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInOperatingActivities
dei:LegalEntity

us-gaap:ProfitLoss
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
dei:LegalEntity

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
dei:LegalEntity

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:EffectiveIncomeTaxRateContinuingOperations
dei:LegalEntity

us-gaap:OperatingLeaseRightOfUseAsset
dei:LegalEntity

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
dei:LegalEntity
us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity
so:AdditionalConstructionCapitalCosts
us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity
so:AdditionalConstructionCapitalCostsThreshold
us-gaap:Range, us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity
dei:LegalEntity
so:AmortizationOfDeferredInvestmentTaxCredits
dei:LegalEntity
so:CapitalContributionsFromToParentCompany
us-gaap:StatementEquityComponents, dei:LegalEntity

so:ChangeInConstructionPayables
dei:LegalEntity
dei:LegalEntity
so:ChangeInConstructionPayablesNetOfJointOwnerPortion
us-gaap:SubsequentEventType
so:CommonStockConversionPrice
us-gaap:PublicUtility, dei:LegalEntity
so:ConstructionFinancingCosts
dei:LegalEntity, us-gaap:StatementScenario
so:ContractWithCustomerLiabilityBillCredits
us-gaap:StatementScenario, dei:LegalEntity
us-gaap:StatementScenario, dei:LegalEntity
so:CurrentBillingRatesUnderRateECRinTermsofPerUnits
us-gaap:PublicUtility, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity
so:CustomerRefund
us-gaap:PublicUtility, us-gaap:SubsequentEventType, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity

so:DepreciationAndAmortizationExcludingNuclearFuel
dei:LegalEntity
us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType, dei:LegalEntity
so:DisposalGroupNotDiscontinuedOperationGainLossonDisposalAfterTax
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
so:DistributionMadeToLimitedPartnerCashDistributionsPaidPercentage
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
so:EquityMethodInvestmentSummarizedFinancialInformationOperatingIncomeLoss

so:ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints
dei:LegalEntity

so:IncreaseDecreaseInAccruedTaxes
dei:LegalEntity
dei:LegalEntity
so:IncreaseDecreaseInCustomerRefunds
dei:LegalEntity
so:IncreaseDecreaseRetailFuelCostOverRecoveryShortTerm

so:IncreaseDecreaseinEnergyRelatedInventoryNaturalGasinStorage
dei:LegalEntity

so:IncreaseDecreaseinFairValueofFundsIncludingReinvestedInterestandDividends
dei:LegalEntity
us-gaap:StatementScenario, dei:LegalEntity
so:LiabilityForClaimsAndClaimsAdjustmentExpenseAnnualRecoveryAmount

so:NoncontrollingInterestIncreasefromContributionsfromNoncontrollingInterestHolders
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity
so:NotionalAmountOfForeignCurrencyDerivativesPayRate
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity
so:NotionalAmountOfForeignCurrencyDerivativesReceiveRate
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity
so:NotionalAmountofInterestRateDerivativesInterestRatePaid
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:VariableRate, so:HedgingMaturityDate, dei:LegalEntity
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity
so:NotionalAmountofInterestRateDerivativesInterestRateReceived

so:PaymentsPursuantToLongTermServiceAgreements
dei:LegalEntity
us-gaap:CounterpartyName, us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity
so:PercentageOfConstructionCostsResponsibilityToPay
us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity
dei:LegalEntity
so:ProceedsFromFederalFinancingBankLoan
us-gaap:PublicUtility, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity
so:PublicUtilitiesRequestedCapitalConstructionCosts
us-gaap:PublicUtility, us-gaap:SubsequentEventType, dei:LegalEntity
us-gaap:PublicUtility, us-gaap:SubsequentEventType, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity
us-gaap:StatementScenario, dei:LegalEntity
dei:LegalEntity
so:RepaymentsOfFederalFinancingBankLoan
dei:LegalEntity
so:RetailFuelCostOverRecoveryLongTerm
dei:LegalEntity
so:ReturnOfPaidInCapital
us-gaap:StatementEquityComponents, dei:LegalEntity
us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent, us-gaap:SubsequentEventType, dei:LegalEntity
so:StormDamagesAnnualRecoveryAmount

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
us-gaap:StatementEquityComponents

us-gaap:AmortizationOfIntangibleAssets
dei:LegalEntity
us-gaap:StatementBusinessSegments, dei:LegalEntity
us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:AmortizationOfRegulatoryAsset

us-gaap:AssetRetirementObligationCashPaidToSettle
dei:LegalEntity

us-gaap:CapitalExpendituresIncurredButNotYetPaid
dei:LegalEntity

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
dei:LegalEntity

us-gaap:CommonStockDividendsPerShareCashPaid
us-gaap:SubsequentEventType
us-gaap:ConversionOfStockSharesConverted1
dei:LegalEntity, us-gaap:StatementScenario
us-gaap:CustomerRefundableFeesRefundPayments1

us-gaap:DeferredIncomeTaxExpenseBenefit
dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses
us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets
us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanInterestCost
us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost
us-gaap:RetirementPlanType, dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanServiceCost
us-gaap:RetirementPlanType, dei:LegalEntity

us-gaap:DepreciationAmortizationAndAccretionNet
dei:LegalEntity
dei:LegalEntity
us-gaap:DerivativeGainLossOnDerivativeNet
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation

us-gaap:DisposalGroupNotDiscontinuedOperationGainLossOnDisposal
dei:LegalEntity
us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, dei:LegalEntity
us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType, dei:LegalEntity

us-gaap:DividendsCommonStockCash
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationRevenue
dei:LegalEntity
us-gaap:ExciseTaxesCollected

us-gaap:GainLossOnDispositionOfAssets1
dei:LegalEntity

us-gaap:IncomeLossFromEquityMethodInvestments
dei:LegalEntity
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, dei:LegalEntity
us-gaap:IncomeLossFromIndividuallySignificantComponentDisposedOfOrHeldForSaleExcludingDiscontinuedOperationsAttributableToParentBeforeIncomeTax

us-gaap:IncreaseDecreaseInAccountsPayable
dei:LegalEntity

us-gaap:IncreaseDecreaseInAccruedSalaries
dei:LegalEntity
dei:LegalEntity
us-gaap:IncreaseDecreaseInFossilFuelInventories
dei:LegalEntity
us-gaap:IncreaseDecreaseInMaterialsAndSupplies

us-gaap:IncreaseDecreaseInOtherOperatingAssets
dei:LegalEntity

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities
dei:LegalEntity

us-gaap:IncreaseDecreaseInPrepaidExpense
dei:LegalEntity
dei:LegalEntity
us-gaap:IncreaseDecreaseInPrepaidTaxes

us-gaap:IncreaseDecreaseInReceivables
dei:LegalEntity

us-gaap:IncrementalCommonSharesAttributableToEquityUnitPurchaseAgreements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InterestPaidCapitalized
dei:LegalEntity

us-gaap:InterestPaidNet
dei:LegalEntity
dei:LegalEntity
us-gaap:InventoryWriteDown

us-gaap:LeaseIncome
dei:LegalEntity

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:OperatingLeaseLeaseIncome
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationBeforeTax
dei:LegalEntity
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk, dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax
dei:LegalEntity
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation
us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation, dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossNetOfTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax
dei:LegalEntity

us-gaap:OtherNoncashIncomeExpense
dei:LegalEntity

us-gaap:PaymentsForProceedsFromOtherInvestingActivities
dei:LegalEntity

us-gaap:PaymentsForRemovalCosts
dei:LegalEntity
dei:LegalEntity
us-gaap:PaymentsOfCapitalDistribution

us-gaap:PaymentsOfDividendsCommonStock
dei:LegalEntity

us-gaap:PaymentsToAcquireEquityMethodInvestments
dei:LegalEntity

us-gaap:PaymentsToInvestInDecommissioningFund
dei:LegalEntity

us-gaap:PaymentsToMinorityShareholders
dei:LegalEntity

us-gaap:PensionAndOtherPostretirementBenefitExpense
dei:LegalEntity

us-gaap:PreferredStockDividendsIncomeStatementImpact
dei:LegalEntity
us-gaap:RelatedPartyTransactionsByRelatedParty, us-gaap:SubsequentEventType, dei:LegalEntity
us-gaap:ProceedsFromContributionsFromAffiliates
us-gaap:SubsequentEventType, dei:LegalEntity
dei:LegalEntity
us-gaap:ProceedsFromContributionsFromParent

us-gaap:ProceedsFromDecommissioningFund
dei:LegalEntity
us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType, dei:LegalEntity
us-gaap:ProceedsFromDivestitureOfBusinesses
dei:LegalEntity
us-gaap:ProceedsFromInterestReceived

us-gaap:ProceedsFromIssuanceOfCommonStock
dei:LegalEntity
us-gaap:ProceedsFromIssuanceOfOtherLongTermDebt
dei:LegalEntity
us-gaap:ProceedsFromIssuanceOfSeniorLongTermDebt
dei:LegalEntity
us-gaap:ProceedsFromMinorityShareholders
dei:LegalEntity
us-gaap:ProceedsFromNotesPayable

us-gaap:ProceedsFromOtherShortTermDebt
dei:LegalEntity

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities
dei:LegalEntity
dei:LegalEntity
us-gaap:ProceedsFromPollutionControlBond

us-gaap:ProceedsFromSaleOfProductiveAssets
dei:LegalEntity

us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity
dei:LegalEntity
dei:LegalEntity
us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount
us-gaap:ProductOrService, us-gaap:StatementScenario, dei:LegalEntity
us-gaap:ProductOrService, us-gaap:SubsequentEventType, dei:LegalEntity
us-gaap:SubsequentEventType, dei:LegalEntity
dei:LegalEntity, us-gaap:PublicUtility, us-gaap:StatementScenario
us-gaap:PublicUtilitiesApprovedReturnOnEquityPercentage
us-gaap:PublicUtility, dei:LegalEntity
us-gaap:PublicUtility, us-gaap:StatementScenario, dei:LegalEntity
us-gaap:StatementScenario, us-gaap:PublicUtility, dei:LegalEntity

us-gaap:RepaymentsOfNotesPayable
dei:LegalEntity

us-gaap:RepaymentsOfOtherShortTermDebt
dei:LegalEntity
dei:LegalEntity
us-gaap:RepaymentsOfPollutionControlBond
dei:LegalEntity
us-gaap:RepaymentsOfSeniorDebt

us-gaap:RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability
dei:LegalEntity

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
dei:LegalEntity

us-gaap:SalesTypeLeaseInterestIncome
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesNewIssues

us-gaap:StockIssuedDuringPeriodValueNewIssues
us-gaap:StatementEquityComponents

us-gaap:StockOptionPlanExpense

us-gaap:StockholdersEquityOther
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents, dei:LegalEntity
dei:LegalEntity
us-gaap:StormDamageProvision

us-gaap:TaxesExcludingIncomeAndExciseTaxes
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations
dei:LegalEntity

us-gaap:VariableLeaseIncome
dei:LegalEntity

dei:EntityCommonStockSharesOutstanding
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:AccumulatedReserveBalanceForFutureStorms

so:AmountOfVariableRatePollutionControlRevenueBondsOutstandingRequiringLiquiditySupport
dei:LegalEntity
dei:LegalEntity
so:ApproximateNameplateCapacity
dei:LegalEntity, us-gaap:BusinessAcquisition, us-gaap:StatementScenario
us-gaap:BusinessAcquisition, us-gaap:StatementScenario, dei:LegalEntity
us-gaap:StatementScenario, us-gaap:BusinessAcquisition, dei:LegalEntity

so:BankCreditArrangementsNoTermLoanDueWithInOneYear
dei:LegalEntity

so:CustomerDepositsCurrent1
dei:LegalEntity

so:DeferredChargesAndOtherAssets
dei:LegalEntity

so:DeferredChargesRelatedToIncomeTaxes
dei:LegalEntity

so:DeferredCreditsRelatedToIncomeTaxes
dei:LegalEntity
dei:LegalEntity
so:DeferredUnderRecoveredRegulatoryClauseRevenues
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
so:DerivativeCumulativeAmountofFairValueHedgingAdjustmentIncludedinCarryingAmount
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:Position, dei:LegalEntity
so:DerivativeNonmonetaryNotionalAmountNetLongShortPositionVolume
us-gaap:PublicUtility, dei:LegalEntity
so:EstimatedCostToCompleteConstructionContingencyEstimateSubjectToRateRecoveryEvaluation
so:Program, dei:LegalEntity
so:EstimatedCosttoCompleteConstructionContingencyEstimate
us-gaap:PublicUtility, dei:LegalEntity
us-gaap:Range, us-gaap:BusinessAcquisition, dei:LegalEntity
so:EstimatedFutureConstructionPayments
us-gaap:DerivativeInstrumentRisk
so:FairValueGainLoss
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity
dei:LegalEntity
so:JointOwnerAccountsReceivable

so:LineOfCreditExpireYearFour
dei:LegalEntity
us-gaap:CreditFacility, dei:LegalEntity

so:LineOfCreditExpireYearOne
dei:LegalEntity

so:LineOfCreditExpireYearThree
dei:LegalEntity

so:LineofCreditExpireYearFive
dei:LegalEntity
us-gaap:StatementScenario, dei:LegalEntity
so:NaturalDisasterReserveAuthorizedLimit
us-gaap:DerivativeInstrumentRisk
so:NetQuantityPurchaseOfDerivativesNotDesignatedAsHedges
us-gaap:DerivativeInstrumentRisk, dei:LegalEntity
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, dei:LegalEntity
so:NonQualifiedDeferredCompensationTrustsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, dei:LegalEntity

so:NuclearFuelAtAmortizedCost
dei:LegalEntity

so:OtherAccountsNotesAndLoansReceivable
dei:LegalEntity

so:OtherCostOfRemovalObligations
dei:LegalEntity

so:OtherRegulatoryAssetsCurrent
dei:LegalEntity

so:OtherRegulatoryAssetsDeferred
dei:LegalEntity

so:OtherRegulatoryLiabilitiesCurrent
dei:LegalEntity

so:OtherRegulatoryLiabilitiesDeferred
dei:LegalEntity
dei:LegalEntity
so:OverRecoveredRegulatoryClauseLiabilities
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:OverUnderRecoveredFuelBalance
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:OverUnderRecoveredNaturalGasBalance
dei:LegalEntity, us-gaap:StatementScenario
so:PercentOfBasisPoints

so:PlantInServiceNetOfDepreciation
dei:LegalEntity
us-gaap:StatementScenario, dei:LegalEntity
so:PortionOfActualEarningsAboveApprovedROEBandRefundedToCustomersValue
us-gaap:PublicUtility, dei:LegalEntity
so:PreliminaryEstimatedCosttoComplete
us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity
dei:LegalEntity
so:PrepaidLongTermServiceAgreements
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:RateCnpPowerPurchaseAgreement
us-gaap:StatementScenario, dei:LegalEntity
so:RecoveryEstimateOfUnderRecoveredCCRRuleCosts

so:RegulatoryAssetAssetRetirementObligation
dei:LegalEntity

so:RegulatoryAssetAssetRetirementObligationCurrent
dei:LegalEntity
dei:LegalEntity
so:RegulatoryAssetStormDamageReservesCurrent
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:RegulatoryClauseAdValoremTax
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:RegulatoryClausePropertyDamageReserve
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:RetailEnergyCostRecovery

so:UnbilledRevenuesCurrent
dei:LegalEntity
us-gaap:BalanceSheetLocation, dei:LegalEntity
so:UnderRecoveredRateCnpBalance

so:WeatherDerivativePremium
dei:LegalEntity
dei:LegalEntity
us-gaap:AccountsPayableOtherCurrent

us-gaap:AccountsReceivableGrossCurrent
dei:LegalEntity

us-gaap:AccountsReceivableNet
dei:LegalEntity

us-gaap:AccrualForTaxesOtherThanIncomeTaxesCurrent
dei:LegalEntity

us-gaap:AccruedEnvironmentalLossContingenciesNoncurrent
dei:LegalEntity

us-gaap:AccruedSalariesCurrent
dei:LegalEntity

us-gaap:AccumulatedDeferredInvestmentTaxCredit
dei:LegalEntity

us-gaap:AllowanceForDoubtfulAccountsReceivableCurrent
dei:LegalEntity

us-gaap:AssetRetirementObligationCurrent
dei:LegalEntity

us-gaap:AssetRetirementObligationsNoncurrent
dei:LegalEntity
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent
dei:LegalEntity
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:BusinessCombinationContingentConsiderationLiability
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity

us-gaap:CollateralAlreadyPostedAggregateFairValue
dei:LegalEntity
us-gaap:DerivativeInstrumentRisk, dei:LegalEntity

us-gaap:ConstructionInProgressGross
dei:LegalEntity
us-gaap:BusinessAcquisition, dei:LegalEntity

us-gaap:ContractWithCustomerAssetNet
dei:LegalEntity
us-gaap:ProductOrService

us-gaap:ContractWithCustomerLiability
dei:LegalEntity
us-gaap:ProductOrService

us-gaap:DebtInstrumentCarryingAmount
dei:LegalEntity

us-gaap:DebtInstrumentFairValue
dei:LegalEntity

us-gaap:DecommissioningFundInvestments
dei:LegalEntity

us-gaap:DeferredCreditsAndOtherLiabilities
dei:LegalEntity
dei:LegalEntity
us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxLiabilitiesNet
dei:LegalEntity
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeAmountOfHedgedItem

us-gaap:DerivativeAssetFairValueGrossLiability
dei:LegalEntity
us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument, us-gaap:MeasurementInputType, us-gaap:ValuationTechnique, dei:LegalEntity
us-gaap:DerivativeAssetLiabilityNetMeasurementInput

us-gaap:DerivativeAssets
dei:LegalEntity
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, dei:LegalEntity
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementFrequency, us-gaap:FinancialInstrument, dei:LegalEntity

us-gaap:DerivativeAssetsCurrent
dei:LegalEntity

us-gaap:DerivativeFairValueOfDerivativeAsset

us-gaap:DerivativeFairValueOfDerivativeLiability
dei:LegalEntity
us-gaap:DerivativeInstrumentsAndHedgesLiabilities

us-gaap:DerivativeLiabilities

us-gaap:DerivativeLiabilityFairValueGrossAsset
dei:LegalEntity
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeLiabilityNotionalAmount
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity

us-gaap:DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent
dei:LegalEntity
us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType, dei:LegalEntity
us-gaap:DisposalGroupIncludingDiscontinuedOperationConsideration
us-gaap:StatementScenario, us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, dei:LegalEntity
dei:LegalEntity
us-gaap:DueFromRelatedPartiesCurrent
dei:LegalEntity
us-gaap:DueToRelatedPartiesCurrent

us-gaap:EnergyMarketingContractLiabilitiesCurrent
dei:LegalEntity

us-gaap:EnergyMarketingContractsAssetsCurrent
dei:LegalEntity

us-gaap:EnergyRelatedInventoryNaturalGasInStorage
dei:LegalEntity

us-gaap:EnergyRelatedInventoryOtherFossilFuel
dei:LegalEntity
dei:LegalEntity
us-gaap:EnvironmentalExitCostsAssetsPreviouslyDisposedLiabilityForRemediation
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
us-gaap:EquityMethodInvestmentOwnershipPercentage

us-gaap:EquityMethodInvestments
dei:LegalEntity
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
dei:LegalEntity
us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsByMajorClass, dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsGross
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsByMajorClass, dei:LegalEntity
us-gaap:PublicUtility, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity
us-gaap:GuaranteeObligationsMaximumExposure
us-gaap:PublicUtility, us-gaap:SubsequentEventType, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity
dei:LegalEntity
us-gaap:IncomeTaxesReceivableNoncurrent

us-gaap:IntangibleAssetsGrossExcludingGoodwill

us-gaap:InterestPayableCurrent
dei:LegalEntity

us-gaap:LeveragedLeasesBalanceSheetInvestmentInLeveragedLeasesNet
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:LiabilitiesFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent
us-gaap:StatementScenario, us-gaap:BalanceSheetLocation, us-gaap:LiabilityForCatastropheClaimsByCatastrophicEvent, dei:LegalEntity
us-gaap:LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet

us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity
dei:LegalEntity
us-gaap:CreditFacility, us-gaap:SubsequentEventType, dei:LegalEntity

us-gaap:LineOfCreditFacilityRemainingBorrowingCapacity
dei:LegalEntity

us-gaap:LongTermDebtAndCapitalLeaseObligations
dei:LegalEntity

us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity
us-gaap:NoncontrollingInterestInVariableInterestEntity

us-gaap:NumberOfStatesInWhichEntityOperates
dei:LegalEntity

us-gaap:OperatingLeaseLiabilityCurrent
dei:LegalEntity

us-gaap:OperatingLeaseLiabilityNoncurrent
dei:LegalEntity
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:OtherAssetsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, dei:LegalEntity

us-gaap:OtherInventorySupplies
dei:LegalEntity

us-gaap:OtherLongTermInvestments
dei:LegalEntity
dei:LegalEntity
us-gaap:PreferredStockValueOutstanding

us-gaap:PrepaidExpenseCurrent
dei:LegalEntity
dei:LegalEntity
us-gaap:PrepaidTaxes
us-gaap:RestrictedCashAndCashEquivalentsCashAndCashEquivalents
us-gaap:RestrictedCash
us-gaap:RestrictedCashAndCashEquivalentsCashAndCashEquivalents, dei:LegalEntity

us-gaap:RevenueRemainingPerformanceObligation
dei:LegalEntity

us-gaap:ShortTermBorrowings
dei:LegalEntity

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:TemporaryEquityCarryingAmountAttributableToParent
dei:LegalEntity, us-gaap:StatementClassOfStock, us-gaap:StatementScenario
us-gaap:TemporaryEquityRedemptionPricePerShare
us-gaap:StatementScenario, us-gaap:StatementClassOfStock, dei:LegalEntity

us-gaap:UnamortizedLossReacquiredDebtNoncurrent

Tables

  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
 us-gaap:SharesIssued us-gaap:StatementEquityComponents us-gaap:CommonStock█████▇▇▇▇▇▇▆▆▆▆▅▄▄▄▄▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▁▁105710541050104610411034102910151012100810041000995991980942921915912911911908900896894892889883880877877875869865862858849843839831825820800796NA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents us-gaap:TreasuryStock████▁▁██▁▁1111001100NANANA0NANANA333300035810101030000000000000NA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents,dei:LegalEntity us-gaap:CommonStock,so:AlabamaPower▄▄▄▄▄▄▄▄▄▄31313131313131313131NANANA31NANANANANANANANANANANANANANANANANANANA31NANANA31NANANA31NANANA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents,dei:LegalEntity us-gaap:CommonStock,so:MississippiPower▄▄▄▄▄▄▄▄▄▄1111111111NANANA1NANANANANANANANANANANANANANANANANANANA1NANANA1NANANA1NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding 1067NA105710521045NA102910141016NA101010051000NA975940922NA912912915NANANA893NA881879875NA883880877NA868862853NA841832824NA800792781
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic 1057NA104810441038NA102310141011NA1003998993NA968934916NA910909910NANANA890NA878874870NA876872868NA860855847NA835828822NA798790779
us-gaap:EarningsPerShareBasic ▆▅▆▆█▄▆▄▆▅▆▁▅▄▆▅▅▄▆▅▅▄▆▅▅▅▆▅▄▅▆▅▅▄▆▅▅▄▆▅▅▄▆▅▄0.820.421.260.862.010.271.14-0.150.930.491.07-1.380.660.21.170.650.530.31.050.690.560.310.80.680.390.470.970.340.090.441.110.710.420.31.070.710.50.180.980.620.60.310.990.610.16
us-gaap:EarningsPerShareDiluted ▆▅▆▆█▄▆▄▆▅▆▁▅▄▆▅▅▄▆▅▅▄▆▅▅▅▆▅▄▅▆▅▅▄▆▅▅▄▆▅▅▄▆▅▄0.810.421.250.851.990.271.13-0.150.920.491.06-1.370.660.21.160.650.530.31.050.690.560.310.80.680.390.470.970.340.090.441.110.710.420.290000000000000041.060.70.490.169999999999999930.970.610.60.300000000000000040.990.60.16
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax ▅▄▇▅▆▅▇▆█▆█▆▇▅█▃▂▁▆▃▃▂▅▃▄▂▅▃▂▁▅▃▁▁▆▃▂▂▅▃▃▁▄▂▁501849145995509854125337615956276372562962015430577151816264445939653568540143374183401753394467464439275017424638973703504941813604369654284521401237715319420741573510468138853666
us-gaap:Revenues ▅▄▇▅▆▅▇▆█▆█▆▇▅█▃▂▁▆▃▃▂▅▃▄▂▅▃▂▁▅▃▁▁▆▃▂▂▅▃▃▁▄▂▁501849145995509854125337615956276372562962015430577151816264445939653568540143374183401753394467464439275017424638973703504941813604369654284521401237715319420741573510468138853666
us-gaap:CostOfGoodsAndServicesSold 439NANANA686NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments,dei:LegalEntity us-gaap:OperatingSegments,so:WholesaleGasServices,so:SouthernCompanyGas1163NA121212381928NA16631454NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService srt:Fuel▁▃█6367861072NA85011231310NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService us-gaap:ElectricityPurchased▂▃▇▃▁▄▇▆█▄▇181191254201170211257236267217256NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService us-gaap:NaturalGasUsRegulated▅▄▁▂█▅▁▃█▆▂43936379191686486104228720516134NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService us-gaap:ProductAndServiceOther▁▃▃▂▃▃▃██▆▂551191148411811812027928922090NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity so:ElectricityPurchasedAffiliates,so:GeorgiaPower129NA150134176NA206178NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity srt:Fuel,so:AlabamaPower▁▃█215248310NA301273356NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity srt:Fuel,so:GeorgiaPower▁▄█231312443NA299429480NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity srt:Fuel,so:MississippiPower▁▂█7988121NA9393116NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity srt:Fuel,so:SouthernPower▁▃█107128166NA145188190NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity us-gaap:ElectricityPurchased,so:GeorgiaPower129NA151124118NA106111NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:ProductOrService,dei:LegalEntity us-gaap:NaturalGasUsRegulated,so:SouthernCompanyGas▅▄▁▂█▆▁▃43936379191686486104228NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:CostsAndExpenses ▄▄▄▄▁▅▄▆▅▅▄█▅▅▄▃▃▃▄▃▃375542243982375617214759398555644996483441567024446545944347327430322990375232393226NANANA3944NA352636063572NA330930382838310737763385315833003861325632353033326629983176
 us-gaap:CostsAndExpenses dei:LegalEntity so:AlabamaPower▁█▇▄▄▆▇▆▅▇▆▃▃▄▆▃▃▂▆▄▄▄▆▅▆9291229116510681070115211791123110111651124103010061076113510149989531140105710551061114910801127NA110410351001NA1093987925101311481036991110912091073NANANANANA
 us-gaap:CostsAndExpenses dei:LegalEntity so:GeorgiaPower▂▂▃▂▂▃▃█▂▂▂▂▁▂▃▂▂▁▄▂▂▃▃▃▄1419149615941470138515621602252014481415151214091331150416441395136312651727146215241614171116141753NA161214901470NA1574148514011536189317281596159619141589NANANANANA
 us-gaap:CostsAndExpenses dei:LegalEntity so:SouthernCompanyGas▆▅▄▄▇▆▁▄█▆▃▄▇889812533555112194311868112519694976201169NA531NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OperatingIncomeLoss ▅▄▆▅█▄▆▃▅▄▆▁▅▄▆▅▄▄▅▅▄▄▅▅▄▄▅▄▄▄▅▅▄▄▅▅▄▄▅▄▄▄▅▄▄126369020131342369157821746313767942045-159413065871917118593357816491098957561127811037007991491640325814174011437665891652113685447014589519214771415886489
 us-gaap:OperatingIncomeLoss dei:LegalEntity so:AlabamaPower▅▁█▅▄▁▇▄▄▃▇▅▄▃█▅▄▃▆▄▄▃▆▄▄▃▆▄▃▃▆▄▃▃▆▄▄▂▆▄422134676445338164561380372268616454376252650430333264555398346267520357381312500357307271544390291258523404329204497389NANANANANA
 us-gaap:OperatingIncomeLoss dei:LegalEntity so:GeorgiaPower▅▄█▆▅▄▇▁▅▅▇▆▅▄█▆▅▅▇▅▅▄▇▅▅▅▇▅▅▅▇▅▄▄▇▅▅▄▆▅4062051161647448257991-47251347010346395012581054656509376964554454288920572516404872552412400924535344222895537393141714411NANANANANA
 us-gaap:OperatingIncomeLoss dei:LegalEntity so:SouthernCompanyGas▇▇▁▄▇▃█▂█▃▃▃█▅▂360318-3513435310437449388110689639118512NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:InterestAndDebtExpense ▆▃▂▁▁▆▆█▆456442434429430456458470458NANA424416404374293246228218180213NANANA206NA202215211NA218220211219217199222228225218222220226232225
 us-gaap:InterestAndDebtExpense dei:LegalEntity so:AlabamaPower██▄▃▄▄▃▂▁888883828383828079NANA7775787774736971696567636362NA656566NA71737375737774767676NANANANANA
 us-gaap:InterestAndDebtExpense dei:LegalEntity so:GeorgiaPower█▆▅▆▂▁▁▄▆111105103105969495102106NANA104101989899949190938986889084NA929691NA959091869071961009587NANANANANA
 us-gaap:InterestAndDebtExpense dei:LegalEntity so:SouthernCompanyGas▇▇▅██▇▁██585856595958525959NANA4846NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherNonoperatingIncomeExpense █▅▆█▇▁▆▇▆▂▄▄▄▂▅▃▃▃▃▄▄10313619978-81577860-5711-3-6-5521-29-21-21-21-12-8NANANA-7NA-10-4-6NA113-2-37-1-42-39-14-9-136-10-3-13
 us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity so:AlabamaPower█▆▆▆▇▄▆▆▅▄▄▅▄▄▄▄▃▁▃▂▄▂▅▄▄2410111114-49125-6-51-5-5-5-4-8-23-7-14-4-173-3-5NA02-1NA-7-4-7-10-7-7-6-12-7-5NANANANANA
 us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity so:GeorgiaPower█▆▆▆▇▄▆▆▇▂▄▅▅▃▄▄▅▆▅▃▃▁▃▃▃522736354011303538-851620311817271810-2211-2NA-11-2NA-1-6-3-3-4-5-1-5-5-1NANANANANA
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▅▄▆▅█▄▆▃▅▄▆▁▅▄▆▅▄▄▅▅▅9863351712107634191201845-26610493241699-193598023916169087194151470945799NANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest dei:LegalEntity so:AlabamaPower▅▁█▅▄▁▇▄▄▃▇▅▄▂▇▅▃▃▆▄▄▃▆▄▄3686761738828396504326311198546386304174575358262204491329292211475302324NA442302248NA474321220182454331258128427319NANANANANA
 us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest dei:LegalEntity so:GeorgiaPower▅▄█▆▅▄▇▁▅▅▇▆▅▄▇▆▅▅▇▅▅▄▇▅▅3471281094577392174926-539445352934551420163967565432312892462380196846493436NA790464325NA84345226315682748332178648359NANANANANA
 us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest dei:LegalEntity so:SouthernCompanyGas▇▇▁▄▇▃█▂█▃▃▃█354307-511123476736224383746780389NA11NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
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us-gaap:IncomeTaxExpenseBenefit ▄▃▄▄█▃▅▃▄▂▅▁▄▃▅▄▄▄▅▄▄145-743671451360-149623-139113-175590-5873159448272222118500302274NANANA176NA46815831NA5693292009654334923110044124723567435225167
 us-gaap:IncomeTaxExpenseBenefit dei:LegalEntity so:AlabamaPower▄▁▆▄▃▂▅▄▄▄█▆▅▄█▆▅▄▇▅▅▄▇▅▅84-25144896219127648275216151126652211421037919212211383183119127NA17411997NA18412684711801319664158119NANANANANA
 us-gaap:IncomeTaxExpenseBenefit dei:LegalEntity so:GeorgiaPower▃▃▆▅▄▃▇▁▄▅█▆▅▄█▆▅▅█▅▅▄▇▅▅166255129812262-143931253501991564336521316011233718014069317177166NA299177124NA314152924230316911120224116NANANANANA
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us-gaap:IncomeTaxesPaidNet ▄▅▅▇▅▅▆▅▅▂▂▅▅▅▄▅▃▅▅█▁-1611552100351335-1-223-1887-63-133-14143273-289NANANA-7NANANA4NANA-362-43-32-357-1-72795330176295172
us-gaap:ProfitLoss ▅▅▇▆█▄▆▄▆▅▆▁▅▄▆▅▅▄▆▅▅841409134593120592691222-1279364991109-13486652301168636497297970643525NANANA368NA86931397NA993639384277933620438169833526510265806494141
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 us-gaap:ProfitLoss dei:LegalEntity so:GeorgiaPower▅▄█▆▅▄▇▁▅▅▇▅▅▄▇▅▅▄▆▅▅▄▆▅▅331122839448311172664-396352227584352264120602352272200555282240127529316270NA491287201NA52930017111452431421058424243NANANANANA
 us-gaap:ProfitLoss dei:LegalEntity so:SouthernCompanyGas█▇▂▄█▄▃▂█▁▃▃▇275238-291062707846-31279-601549239NA4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTax ▅▅▆▆█▄▆▄▆▅▆▁▅▄▆▅821399127586420842521175-1429684881078-13836492421161620NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest 794NA13048962059NA1233-115966NA1118-1350649NA1152609371276944651493NANANA353NA85430285NA976616374231897608426155819514503245794486134
 us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity so:AlabamaPower285NA474300222NA378263230NA331236179NA355217158127293212175124292183197NA268184151NA2781741309825618915453259189NANANANANA
 us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity so:GeorgiaPower330NA804421312NA665-395353NA585353265NA603353273201545297226123529317270NA492287202NA52629516811052130920756422241NANANANANA
 us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity so:SouthernCompanyGas260NA-32103269NA52-30281NA1548237NA1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic ▆▅▆▆█▄▆▃▆▅▆▁▅▄▆▅▅▄▆▅▅▄▅▅▄▅▆▄▄▅▆▅▅▄▆▅▅▄▅▅▅▄▅▅▄868409131689920842691164-1549384961069-1381658197113061248527195962950828371861135141485229781383976623368261916604422153817510494249789478125
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic dei:LegalEntity so:AlabamaPower▅▂█▅▄▁▆▄▄▂▆▄▃▂▆▄▃▂▅▃▃▂▅▃▃▂▄▃▂▂▅▃▂▂▅▃▃▁▄▃280884692962177337325922511932523017410235021115512129520016911928217318714025817314111328018512610226419015255259190NANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic dei:LegalEntity so:GeorgiaPower▅▄█▆▅▄▇▁▅▅▇▅▅▄▇▅▅▄▆▅▅▄▆▅▅▄▆▅▄▄▆▅▄▄▆▅▄▄▆▅331122839448311173664-39635222758034726011359834726819655127723612352531126620848728219718152529516711052030920654420238NANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic dei:LegalEntity so:SouthernCompanyGas█▇▂▄█▄▃▂█▁▃▃▇▅▂275238-291062707846-31279-6015492391104NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:ConsolidationItems,dei:LegalEntity us-gaap:OperatingSegments,so:SouthernCompanyGas██▂▄█▃▃▁274271301032738368-8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:ConsolidationItems,us-gaap:ProductOrService,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,so:ElectricUtilities,so:TraditionalElectricOperatingCompanies642NA1373782565NA1148-48NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,so:SouthernCompanyGas275NA-29106270NA46-31279NA1549NANA4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments,dei:LegalEntity us-gaap:OperatingSegments,so:GasDistributionOperations,so:SouthernCompanyGas█▅▁▂▆▁▃▃1641093758133447468NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:ProductOrService so:ElectricUtilities▅▂█▆▄▃▇▁▅71723314599566213581240-26733NANA-13605021801194684514308976607510284722611351NA85029695NA977596369271918603423170818505496260793452NA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:StatementEquityComponents us-gaap:RetainedEarnings868NA13168992084NA1164-154938NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:StatementEquityComponents,dei:LegalEntity us-gaap:RetainedEarnings,so:AlabamaPower280NA469296217NA373259225NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:StatementEquityComponents,dei:LegalEntity us-gaap:RetainedEarnings,so:GeorgiaPower331NA839448311NA664-396352NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic us-gaap:StatementEquityComponents,dei:LegalEntity us-gaap:RetainedEarnings,so:SouthernCompanyGas275NA-29106270NA46-31279NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▁▁▆▆▂▃█▆▃▄▆▆▃▄▆▅▄▅▄▄▄-31-362529-29-135423-6-23022-4-32712114000NANANA17NA171616NA171616161716161616161616161616
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:Assets ██████▇▇▇▇▇▇▇▇▇▅▄▄▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁118852118700117591114867114096116914111717112777111567111005110315108684109760109697106362908737873578318752157418171610709236765466400648386454664697639616327463149619636089759874592675734356023550195503254894533745258052046NANANA
 us-gaap:Assets dei:LegalEntity so:AlabamaPower███▇▇▆▆▆▅▅▄▄▄▄▄▃▃▃▃▃▃▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁293682915229019280672740726730266102627024317238642378923133228692251622457221562197721721216332122020756205522029319530193621925119352188381876918712188261855418664184771851518230NA17994NANANANANANANA
 us-gaap:Assets dei:LegalEntity so:GeorgiaPower███▇▇▆▅▅▅▅▅▅▄▄▄▄▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▁▁▁▁451794454144415432394253840365368613596137199367793710636188352483483534248340153280232865317263174831516310302991529669291892890729207291272899528803284212807827337271512670526469NA25914NANANANANANANA
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 us-gaap:Assets dei:LegalEntity so:SouthernPower▇▇▇▇██████████▆▅▄▄▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁1364614300143971451815104148831535515428151821520614648147031468115169123511108289998905704062265564554946084605440344294449413938583779378137853596358037573536NA3437NANANANANANANA
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us-gaap:Liabilities ███▇▇█▇█▇▇▇▇▇▇▆▃▁▁866458665085509834458311887584833288576185218851538395683274824828280380015672625638956175NANANA49583NANA446374440744788447904415543770422424169141093406073862837959374723774837558367593630336086NANANA
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 us-gaap:Liabilities dei:LegalEntity so:GeorgiaPower████▇▆▄▄▅▅▅▅▄▄▄▄▄▄▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁▁296672947629651289232826926042230102325923779248482483324209233322321322717228142164721880207052102920844203431962219681192881905019342195331947119264187761874618089178621712017199NA16907NANANANANANANA
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 us-gaap:LiabilitiesAndStockholdersEquity dei:LegalEntity so:SouthernCompanyGas▄▄▃▂▂▄▁▆▇█▆▅▄▅2161721687210472076120952214482039822112225682298722190218092168321853NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
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us-gaap:CashAndCashEquivalentsAtCarryingValue ▆▅█▃▃▃▅▅▆▅▅▃▂▅▇▅▁▃▂▁▂▁2164197529311383136113961847198022842130184114331094197526691897754140411098131112710NANA59065968242451562812566591044131515164374104471258266339690606781672
 us-gaap:CashAndCashEquivalentsAtCarryingValue dei:LegalEntity so:AlabamaPower▆▆█▄▅▂▅▄▄▄▆▄▄▃▄▃▃▂▄▂▃▂▄▁▂▂▃▁▁▁▃▁▃▃▄▂▂▂▃▁8988941337623759313702686653544953639696420556343444194609195395273662105252295436596513736678355344576162159154368100NA368NANANA
 us-gaap:CashAndCashEquivalentsAtCarryingValue dei:LegalEntity so:SouthernCompanyGas█▂▂▂▂▂▂▂▃▂▁▂▁▁▂▁311465956576456699473213828194815NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CashAndCashEquivalentsAtCarryingValue dei:LegalEntity so:SouthernPower▃▃▃▃▂▂▂▂▂▂▂▂▂███▁▆▂▂▁▁▂▁▂▁▁▁▁▁▁▁▁▁▂▁▁▁▁▁33027936837013318119214282129178999310991091102253830161220237486231296842147528163216205661404NA7NANANA
us-gaap:OtherAssetsCurrent ▅▅▅▃▃▄▆▄█▆▅▅▇▆▄▁▂▁179188208138132162232172286211209206249230168719071NANANA50NANA7039333560746066594610051535966405249NANANA
 us-gaap:OtherAssetsCurrent dei:LegalEntity so:AlabamaPower▄▃▃▃▂▂▁▂▁█▁▁▁▂▁▂▂▂▁▂▁▁▁▂▂▁▁▁▂▂▂▁▂▂▂▂3730242621188113905781191010109104591613633141311812111110NA10NANANANANANANA
 us-gaap:OtherAssetsCurrent dei:LegalEntity so:GeorgiaPower▄▄▆▃▃▄▅▁▂▁▂▁▂▂▅▃▃▅▅▅▅▄▇▅▆▃▄▃▃▆▆▅▅▆█▃6977101584870912339152722383889556192948685741188210854754848104111818410614452NA80NANANANANANANA
 us-gaap:OtherAssetsCurrent dei:LegalEntity so:SouthernCompanyGas▄▄▄▄▄▅█▄▅▃▂▂▁▁4341434442508842512825201611NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OtherAssetsCurrent dei:LegalEntity so:SouthernPower▁█▆▄▆▆▃▄▅▅▂▂▄▇▄▄24433833373729313536262631393231NA301916NA21NANANANANANANANANANANA000NA0NANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:PropertyPlantAndEquipmentGross ██▇▇▇▇▇▇█▇▇▇▇▆▅▂▁▁10593110511410352910342810267310370610067299626104499103542102014101021997749841694174781127655375118NANANA70013NANA663696602164793641506358663251619806157760073597445807957817574085673156029556985490953588NANANA
 us-gaap:PropertyPlantAndEquipmentGross dei:LegalEntity so:AlabamaPower██▇▇▇█▇▇▆▆▅▅▅▅▅▅▄▄▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁303483002329648290702881030402295682937427520273262661926466261342603125800255722518724750239222381223254230802268822533222342209221916216742150821407212532111020999208092053020394NA19966NANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross dei:LegalEntity so:GeorgiaPower██▇██▇▆▆▆▆▆▆▅▅▅▅▄▄▄▄▄▄▃▃▃▃▃▃▃▂▂▂▂▂▁▁384363813737409385173801537675356713546735177348613458934410340593384133394330453231831841315463136331425310833081830545302953013229762296722946229244286672854927884278042691826837NA26397NANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross dei:LegalEntity so:SouthernCompanyGas██▇▅▄▃▂▁▇▆▄▂▂▁1645616344160581568015417151771477114504160561583315383148501466014508NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross dei:LegalEntity so:SouthernPower███▇█████████▇▅▄▄▄▃▃▃▃▂▂▂▂▂▂▂▂▁▁▁▁▁▁13282132701307212862132841327113603134021380313755137341373113493127289491834877387275604960475658565649414942470546964203407640324059371436023158316731623157NA3143NANANANANANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment ▇▇▇▇▇▇▇▆██▇▇▇▆▆▁▁▁311803076530469306933083431038307393025531920314573116430667303302985229590247782456624253NANANA24059NANA233292305922821225332221921964219062161621327211542089120657203842017419947196471937119121NANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity so:AlabamaPower▇▇▇▇▇███▇▇▇▆▆▆▆▅▅▅▅▅▅▄▄▄▄▃▃▃▃▃▂▂▂▂▁▁960895409465939794479988993298139693956394639354924191129018888987918736862385658627852284308315822681148016791678167761765975627446734472477127NA6931NANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity so:GeorgiaPower▇▆▆███▇▇▇▆▆▆▅▅▅▄▄▄▄▄▅▅▅▄▄▄▃▃▂▂▂▂▂▂▁▁119291175311670121401221012096120291190111818117041165511502114431131711234110871104510903110461096111326112221119211056110281097010842107371057410431105371039510294102961019810137NA9966NANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity so:SouthernCompanyGas██▇▅▄▃▂▁█▇▆▆▅▄46514650459045224466440043514293467045964567455044984439NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PropertyPlantAndEquipmentNet ██▇▇▇▇▆▆▇▇▇▆▇▆▅▂▁▁839658308081713811748163780797784327719280947798727974178686798117844675554638936255261114NANANA54868NANA515735120850200493174868748390472744656645855450104379743279427014200241199406303999839230NANANA
 us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity so:AlabamaPower██▇▇██▇▇▆▅▅▅▄▄▄▄▄▄▃▃▃▃▂▂▂▂▂▂▁▁▁▁▁▁▁▁218072166921314210922202121851214092107019311190101839818113178671774617600174741730517178167411660216075159121557715374151791505814895146791458314438143031428514255141691408414039NA13865NANANANANANANA
 us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity so:GeorgiaPower██▇▇▇▇▆▅▅▅▆▆▅▅▅▅▄▄▄▃▃▃▃▃▃▃▂▂▂▂▂▂▁▁▁▁332573258931973321193166830962288252825928709283142923628889283692803227604273532683026456254442513425044246662424423971236932342523046228832273922466219812172221568212802097820721NA20104NANANANANANANA
 us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity so:SouthernCompanyGas█▇▆▅▅▄▃▂▆▅▄▃▂▁1248512307120141178611528113571108010782118971172811412110791078710565NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity so:SouthernPower▇▇▇▇▇▇███████▇▆▅▅▄▃▂▂▂▂▂▁▂▂▁▁▁▁▁▁▁▁▁11236113211123911026114051153012102122141244812356123361238612223116429678882679747164583751234613463239714030378838343827364733043298330432993215318231543145NA3035NANANANANANANA
us-gaap:LongTermInvestments ▇▇▇▇▇▇▇▇███████▁▁▁101781033410528106491051110296104821042711474115101161311566115521142011340332527892752NANANA2492NANA240723482275222422302189215921552194211820562232226622712042195620681963NANANA
 us-gaap:LongTermInvestments dei:LegalEntity so:AlabamaPower▆█▇▇▇▆▇▇▆▇▆▆▅▅▅▅▄▄▄▄▄▄▄▄▄▄▃▃▃▂▂▂▂▁▁▂1048121711661157112610391128109610861094105510341003970953929913904872914922906888888864848805776774736724705724675637706NA687NANANANANANANA
 us-gaap:LongTermInvestments dei:LegalEntity so:GeorgiaPower▆███▇▅▆▆▆▆▆▅▅▄▄▄▄▃▃▄▄▃▃▃▃▃▂▂▂▂▁▁▂▁▁▃1049112911091103106599610441037104110411018981957920938923896882861912901885867874876841813798811787773770799774759860NA930NANANANANANANA
 us-gaap:LongTermInvestments dei:LegalEntity so:SouthernCompanyGas▁▁▂▂▂▂▂▂▇▇████64336356660066296685667466776667771377457897791879327895NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:Goodwill ▇▇▇▇▇▇▇▇███████▁528052805280528252845315531553156226626862676271625162516223264NA2NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Goodwill dei:LegalEntity so:SouthernCompanyGas▁▁▁▁▁▁▁▁██████50155015501550155015501550155015592559675967596759675967NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Goodwill us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,so:SouthernCompanyGas▄▄▄▄▄▄▄▄50155015501550155015501550155015NA5967NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:IntangibleAssetsNetExcludingGoodwill ▁▂▂▂▂▃▄▄▆▇▇▇▇██▁523536550550585613674702848873902929935970942490NA317NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:IntangibleAssetsNetExcludingGoodwill dei:LegalEntity so:SouthernCompanyGas▁▁▁▁▂▂▂▂▆▆▆▇▇█6570788593101113125264280300320340366NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:FiniteLivedIntangibleAssetsNet ▁▂▃▃▆█448461475475510538NANA773798827854860895867415NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet dei:LegalEntity so:SouthernCompanyGas▁▁▁▁▂▂▂▂▆▆▆▇▇█6570788593101113125264280300320340366NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass so:PPAFairValueAdjustments▁█316321NANANA344NANANA409NANANA434NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass us-gaap:CustomerRelationships▁▂▃▄▅█9196101106111129NANANA205NANANA236NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass,dei:LegalEntity so:PPAFairValueAdjustments,so:SouthernPower▄▆█▁316321325311NA344NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass,dei:LegalEntity us-gaap:CustomerRelationships,so:SouthernCompanyGas▁▃▆█48525761NA72NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:IntangibleAssetsNetIncludingGoodwill dei:LegalEntity so:SouthernPower▁▂▂▁▃▃▅▆▆▇▇▇██317322326313340345391398404411417423430436NANANA319NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ▅▄▄▄▅▇▆▇█▇▇▆▆▆▄▂▁▁126710711156114112921463143614971653157715131387135713951133833771737NANANA904NANA705551586547570549568455451481491479433436458436414395NANANA
 us-gaap:OtherAssetsNoncurrent dei:LegalEntity so:AlabamaPower█▇▄▄▄▄▄▅▄▄▄▃▃▃▂▁▁▁▃▃▃▃▂▂▂▂▂▂▂▃▃▂▃▄▄▅307269189177193189202212193189178166156163118113109103163156161162142134126142134134128162158144161186193218NA196NANANANANANANA
 us-gaap:OtherAssetsNoncurrent dei:LegalEntity so:GeorgiaPower▆▆▅▄▄▇▆▇▇▇██▆▅▁▁▁▁▅▅▅▅▃▃▃▂▂▃▃▃▃▂▂▁▂▂481500398379379514510570550548608589473417175170157173399446443403294284283246244271279268255221203187213218NA207NANANANANANANA
 us-gaap:OtherAssetsNoncurrent dei:LegalEntity so:SouthernCompanyGas█▄▂▂▂▃▅▅▆▅▃▂▂▁261207189186185193218227232218190186188170NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OtherAssetsNoncurrent dei:LegalEntity so:SouthernPower▃▃▃▄▅▅▆▆█▇▆▆▇█▅▃▂▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁2162162072893423734264636005664554105316263551731371391461431131118987726883674237312629262421NA16NANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:LiabilitiesCurrent ▃▆▄▄▃█▆█▇▇▆▆▆▆▄▂▁▂9553125461053410999991914286129651436613630135941260312751122841291710567851478569129NANANA8967NANA483555365704734664397014656960886317657756575699603764725994593555155584NANANA
 us-gaap:LiabilitiesCurrent dei:LegalEntity so:AlabamaPower▆█▅▄▃▇▇▅▅▄▅▄▄▇▄▄▄▅▆▅▆▅▃▂▂▁▃▃▃▃▅▄▅▅▁▁17002060145513951242195918761610154514001591143113431898136113241308159517961590168916041224109195693211891136112011431617139815801492867849NA1104NANANANANANANA
 us-gaap:LiabilitiesCurrent dei:LegalEntity so:GeorgiaPower▄▇█▇▅▅▄▅▄▆▄▅▂▄▃▄▂▄▅▅▆▄▃▂▁▃▃▄▄▅▄▄▄▄▁▂337146974939448438713909347437063130394933833686270234762982315123633295372338404301347028582504209629062748328231813668349132333139314122912604NA3169NANANANANANANA
 us-gaap:LiabilitiesCurrent dei:LegalEntity so:SouthernCompanyGas▂▃▁▃▄▇▃▇▆█▄▄▅▆18262010158321112306302421713105282034012392223525852918NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LiabilitiesCurrent dei:LegalEntity so:SouthernPower▅▇▅▅▅▅▄▃▅▅▆▇▆█▆▇▆▅▄▃▄▄▃▁▁▁▂▃▂▁▂▂▂▂▄▂1110170412381203101410318135711235123214011627133619031517162813431239916744958947696236120127359543265197272459345331794355NA428NANANANANANANA
us-gaap:AccountsPayableCurrent ▂▅▄▄▅█▆▅▅█▇▄▃▆▃▁▂▄165321151898197820372580224621622089253023531920175022281732149315841905NANANA1593NANA138613761281146713691387128012531262155313551423131512751160128212291329NANANA
us-gaap:AccruedIncomeTaxesCurrent ▁▁▃▃▅█250179171340656NANANA6176125258193375131419NANANA151NANA11413879138765175113461313877257413NANANA
 us-gaap:AccruedIncomeTaxesCurrent dei:LegalEntity so:SouthernCompanyGas▄▁▁▂█▆▁█▇▄▁▃▅▃370017896608677400235026NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccruedIncomeTaxesCurrent dei:LegalEntity so:SouthernPower▁█926NA23116233NANA010135481481479919837657181202171036512171NA0NANANANANANANA
us-gaap:OtherLiabilitiesCurrent ▇▆▇▅▅▇▅▆█▇▅▆▇▃▇▄▁▂868830881793754852763808923868752799867683851694564590NANANA544NANA358347429465462483426443393426380440493535311362360292NANANA
 us-gaap:OtherLiabilitiesCurrent dei:LegalEntity so:AlabamaPower▅▅▆█▄█▂▇▂▂▂▃▃▃▃▁▁▁▆▅▅▄▂▁▁▁▁▁▁▁▁▁▁▁▁▁109105122155971614614357595063717665413939118105114804440394142373838374040383541NA41NANANANANANANA
 us-gaap:OtherLiabilitiesCurrent dei:LegalEntity so:GeorgiaPower▄▃▄█▆▃▃▃▄▃▃▃▄▃▃▆▄▂▇▆█▃▃▂▂▁▁▂▁▂▂▃▂▂▂▂233187234383305183180205215198192185241182197299211143345309388204177148160122109140119137131197144139162159NA134NANANANANANANA
 us-gaap:OtherLiabilitiesCurrent dei:LegalEntity so:SouthernCompanyGas▃▄▄▃█▄▃▆▆▂▂▂▃▁121128127124160130122143143113112113124108NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OtherLiabilitiesCurrent dei:LegalEntity so:SouthernPower▆▇▇▆▆▇█▇▇▇▃▄▄▄▅▄▃▃▃▃▂▁▁▂▁▂▂▁▁▁▁▂▂▁▁▁11913213311611114216514614514358676970976949445653191462212182137881817755NA3NANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent ▁▁▂▃▃▃▂▂▃▄▃▃▄▄█▅▅▆177818141999205820842147201720092206225621392156223422993022248525462582NANANA2432NANA144614612548250425262540244924092432244216081563157515802336228722992304NANANA
 us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent dei:LegalEntity so:AlabamaPower▁▂▅▅▅▅▄▄▅▅▅▄▅▅▇▇██▆▅▆▆▂▁▁▁▆▅▆▆▇▆▆▆▆▅198206296309302314283275297304289269288300366360377388319308322326203186193195323310319321356339343343323306NA311NANANANANANANA
 us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent dei:LegalEntity so:GeorgiaPower▁▂▁▂▂▂▃▃▃▃▃▃▄▄▇▇▇█▇▆▇▇▂▂▂▂█▇██▇▇▇▇▄▄497540525550567599650636651659665652673703906901930949893870891903580539541542976941945950922892901905716683NA684NANANANANANANA
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  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▂▂▆▄▁▃▆▄▄▃▇▅▂▁▆▃▂▃█▃▂89490023681769744136123261749150911422511184589763221471250865118629811194913NANANA1103NANANA737NANA118956813052209139199846421116767389031740218401
 us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity so:AlabamaPower▁▂▆▄▁▄▆▄▁▃▆▄▁▃▆▄▃▅█▂▂▂▆▃▃155308776549146492737497155426739544128414732464339563982307290311724322352NANANA270NANA341140490739492327218657NANANANANANA
 us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity so:GeorgiaPower▂▃▇▅▂▃▇▄▂▃▆▂▁▁▆▄▃▂█▃▂▂▇▂▃21354212539002125361161699373432998371111165109160656335713864113632951225344499NANANA428NANA60331255310686613501401013NANANANANANA
 us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity so:SouthernCompanyGas▆▄▄▅▇▄▁▅█▂▄▅▇6431811824868328-582340978-266-2393758NA-342NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▅▆▆█▅▇▆▆▆▆▆▅▅▅▁▅▅▆▆▆-889-2319-2075-14522454-2260124-1629-1995-504-1798-2086-2803-3408-3965-10478-2197-2400-2114-1659-1107NANANA-1215NANANA-1279NANA-1364-1427-1285-834-1180-884-1250-970-947-1088-1462-1051-683-1122
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity so:MississippiPower▇▇▇▇▇▇▇▇▇█▆▅▅▅▄▇▄▄▄▄▄▃▂▁▁-71-65-70-65-63-62-62-56-52-21-122-171-190-188-213-82-214-220-226-227-233-289-316-372-361NANANA-352NANA-366-344-327-156-145-52-121-74NANANANANANA
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity so:SouthernPower█▆▆▇▆▇▆▆▆▆▆▆▃▁▃▃▄▃▄▅▆▅▆▆▆600-203-218333-7997-47-124-153-132-100-156-1235-1789-1023-1112-873-1084-884-532-38-526-26-246-14NANANA-66NANA-143-47-64-59-119-84-200-80NANANANANANA
us-gaap:NetCashProvidedByUsedInFinancingActivities ▃▃▃▃▁▃▁▃▃▃▃▃▃▄▄█▃▃▂▃▃1854621256-295-3353527-2576-393629-349-305580102520822590103716821509-571166596NANANA43NANANA429NANA-210588-221-296-184-151-26-148198-1642-863574976
 us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity so:AlabamaPower▅▃▆▃█▃▃▄▆▃▄▃▆▃▃▃▅▁▃▃▅▃▅▃▃273-227375-194811-192-19647518-17633-171477-194-178-192279-539-145-194145-136227-115-140NANANA-95NANA-389106-467-148-156-98-181-200NANANANANANA
 us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity so:GeorgiaPower█▆▆▅█▆▅▁▇▂▄▇▇▇▃▅▆▆▂▄▇▇▃▆▅742153145-456659228-1121601-768-314458473380-577-64119181-828-314431414-667121-31NANANA85NANA99369-104-655-15881-14460NANANANANANA
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us-gaap:NetCashProvidedByUsedInOperatingActivities ▂▂▆▄▁▃▆▄▄▃▇▅▂▁▆▃▂▃█▃▂89490023681769744136123261749150911422511184589763221471250865118629811194913NANANA1103NANANA737NANA118956813052209139199846421116767389031740218401
 us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity so:AlabamaPower▁▂▆▄▁▄▆▄▁▃▆▄▁▃▆▄▃▅█▂▂▂▆▃▃155308776549146492737497155426739544128414732464339563982307290311724322352NANANA270NANA341140490739492327218657NANANANANANA
 us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity so:GeorgiaPower▂▃▇▅▂▃▇▄▂▃▆▂▁▁▆▄▃▂█▃▂▂▇▂▃21354212539002125361161699373432998371111165109160656335713864113632951225344499NANANA428NANA60331255310686613501401013NANANANANANA
 us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity so:SouthernCompanyGas▆▄▄▅▇▄▁▅█▂▄▅▇6431811824868328-582340978-266-2393758NA-342NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▅▅▇▆█▄▆▄▆▅▆▁▅▄▆▅▅▄▆▅▅841409134593120592691222-1279364991109-13486652301168636497297970643525NANANA368NA86931397NA993639384277933620438169833526510265806494141
 us-gaap:ProfitLoss dei:LegalEntity so:AlabamaPower▅▁█▅▄▁▆▄▄▂▅▄▃▂▆▃▂▂▅▃▃▂▅▃▃2849247329922177377262229123330235178109354216159125299207179128292183197NA268183151NA29019513611127420016264269200NANANANANA
 us-gaap:ProfitLoss dei:LegalEntity so:GeorgiaPower▅▄█▆▅▄▇▁▅▅▇▅▅▄▇▅▅▄▆▅▅▄▆▅▅331122839448311172664-396352227584352264120602352272200555282240127529316270NA491287201NA52930017111452431421058424243NANANANANA
 us-gaap:ProfitLoss dei:LegalEntity so:SouthernCompanyGas█▇▂▄█▄▃▂█▁▃▃▇275238-291062707846-31279-601549239NA4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▅▆▆█▅▇▆▆▆▆▆▅▅▅▁▅▅▆▆▆-889-2319-2075-14522454-2260124-1629-1995-504-1798-2086-2803-3408-3965-10478-2197-2400-2114-1659-1107NANANA-1215NANANA-1279NANA-1364-1427-1285-834-1180-884-1250-970-947-1088-1462-1051-683-1122
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity so:MississippiPower▇▇▇▇▇▇▇▇▇█▆▅▅▅▄▇▄▄▄▄▄▃▂▁▁-71-65-70-65-63-62-62-56-52-21-122-171-190-188-213-82-214-220-226-227-233-289-316-372-361NANANA-352NANA-366-344-327-156-145-52-121-74NANANANANANA
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity so:SouthernPower█▆▆▇▆▇▆▆▆▆▆▆▃▁▃▃▄▃▄▅▆▅▆▆▆600-203-218333-7997-47-124-153-132-100-156-1235-1789-1023-1112-873-1084-884-532-38-526-26-246-14NANANA-66NANA-143-47-64-59-119-84-200-80NANANANANANA
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▄█▆▅▅█▆▇▅█▆▆▃▇▅▄▆█▂▁▁156021381933180616782208196520471781218118441910148820581766161418722184125111481091NANANA1180NANANA1197NANA1125123114109891040108611929588811054149098610561136
 us-gaap:PaymentsToAcquirePropertyPlantAndEquipment dei:LegalEntity so:AlabamaPower▂▅▃▄▃▇▅▅▅█▄▄▁▂▁▂▁▄▂▁▂▅▂▂▁340518406443390629532507490671473432306325302332313429326287325491329350287NANANA274NANA192244283209272213218202NANANANANANA
 us-gaap:PaymentsToAcquirePropertyPlantAndEquipment dei:LegalEntity so:GeorgiaPower▇█▇▇▇▇▆▆▅▆▄▅▃▄▂▂▃▆▂▁▁▄▁▁▂849929869837875840775820681797623728556657508505553770468431422659458446460NANANA419NANA336476498432418513562516NANANANANANA
 us-gaap:PaymentsToAcquirePropertyPlantAndEquipment dei:LegalEntity so:SouthernCompanyGas▁▇▇▅▁▅▅█▂█▇▆▃261400405347256359350411268421409383301NA287NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▃▃▃▃▁▃▁▃▃▃▃▃▃▄▄█▃▃▂▃▃1854621256-295-3353527-2576-393629-349-305580102520822590103716821509-571166596NANANA43NANANA429NANA-210588-221-296-184-151-26-148198-1642-863574976
 us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity so:AlabamaPower▅▃▆▃█▃▃▄▆▃▄▃▆▃▃▃▅▁▃▃▅▃▅▃▃273-227375-194811-192-19647518-17633-171477-194-178-192279-539-145-194145-136227-115-140NANANA-95NANA-389106-467-148-156-98-181-200NANANANANANA
 us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity so:GeorgiaPower█▆▆▅█▆▅▁▇▂▄▇▇▇▃▅▆▆▂▄▇▇▃▆▅742153145-456659228-1121601-768-314458473380-577-64119181-828-314431414-667121-31NANANA85NANA99369-104-655-15881-14460NANANANANANA
us-gaap:ProceedsFromIssuanceOfLongTermDebt 2653NA33471701220NA850500600NA111015491409NA2053100411997NA9172525550NANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RepaymentsOfLongTermDebt 1481NA6561312429NA111920961283NA503870608NA1133384888NA1623606333NANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:RepaymentsOfLongTermDebt 1481NA6561312429NA111920961283NA503870608NA1133384888NA1623606333NANANANANANANANANANANANANANANANANANANANANANANANA

Common Stock Value

Common Stock Par Or Stated Value Per Share

Shares Issued

us-gaap:StatementEquityComponents

us-gaap:SharesIssued

us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302008-12-312007-12-312006-12-31
Value105710541050104610411034102910151012100810041000995991980942921915912911911908900896894892889883880877877875869865862858849843839831825820800796777763751
Percentage of SharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TreasuryStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302008-12-312007-12-312006-12-31
Value1111001100033330003581010103000000000000000-5
Percentage of SharesIssued0.10.10.10.10.10.10.10.10.10.10.10.40.40.40.40.10.10.10.40.60.91.11.11.10.40.10.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.7

us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:CommonStock, so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312011-12-312010-12-312009-12-312008-12-31
Value313131313131313131313131313125
Percentage of SharesIssued2.92.93.03.03.03.03.03.13.13.13.13.63.73.83.2

us-gaap:CommonStock, so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312011-12-312010-12-312009-12-312008-12-31
Value111111111111111
Percentage of SharesIssued0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1

Common Stock Shares Issued

Common Stock Shares Outstanding

Common Stock Shares Authorized

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-312009-09-302009-06-302009-03-31
Value1067105710521045102910141016101010051000975940922912912915893881879875883880877868862853841832824800792781
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-312009-09-302009-06-302009-03-31
Value10571048104410381023101410111003998993968934916910909910890878874870876872868860855847835828822798790779
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value0.820.421.260.862.010.271.14-0.150.930.491.07-1.380.660.21.170.650.530.31.050.690.560.310.80.680.390.470.970.340.090.441.110.710.420.31.070.710.50.180.980.620.60.310.990.610.16
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value0.810.421.250.851.990.271.13-0.150.920.491.06-1.370.660.21.160.650.530.31.050.690.560.310.80.680.390.470.970.340.090.441.110.710.420.290000000000000041.060.70.490.169999999999999930.970.610.60.300000000000000040.990.60.16
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenue From Contract With Customer Including Assessed Tax

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value501849145995509854125337615956276372562962015430577151816264445939653568540143374183401753394467464439275017424638973703504941813604369654284521401237715319420741573510468138853666
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value501849145995509854125337615956276372562962015430577151816264445939653568540143374183401753394467464439275017424638973703504941813604369654284521401237715319420741573510468138853666
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Cost Of Revenue

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold



Period End2020-03-312019-03-31
Value439686
Percentage of CostOfGoodsAndServicesSold100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax8.712.7

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments, dei:LegalEntity

us-gaap:OperatingSegments, so:WholesaleGasServices, so:SouthernCompanyGas



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value116312121238192816631454
Percentage of CostOfGoodsAndServicesSold264.90.00.0281.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax23.220.224.335.627.025.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:WholesaleGasServices so:SouthernCompanyGas0.00.00.00.00.00.0

us-gaap:ProductOrService

srt:Fuel



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value636786107285011231310
Percentage of CostOfGoodsAndServicesSold144.90.00.0123.90.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.716.017.915.721.021.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Fuel0.00.00.00.00.00.0

us-gaap:ElectricityPurchased



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value181191254201170211257236267217256
Percentage of CostOfGoodsAndServicesSold41.20.00.00.024.80.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax3.63.94.23.93.14.04.24.24.23.94.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ElectricityPurchased0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NaturalGasUsRegulated



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value43936379191686486104228720516134
Percentage of CostOfGoodsAndServicesSold100.00.00.00.0100.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax8.77.41.33.712.79.11.74.111.39.22.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:NaturalGasUsRegulated0.00.00.00.00.00.021.10.00.00.025.2

us-gaap:ProductAndServiceOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value551191148411811812027928922090
Percentage of CostOfGoodsAndServicesSold12.50.00.00.017.20.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.12.41.91.62.22.21.95.04.53.91.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductAndServiceOther0.00.00.00.00.00.060.30.00.00.053.6

us-gaap:ProductOrService, dei:LegalEntity

so:ElectricityPurchasedAffiliates, so:AlabamaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value187369216943
Percentage of CostOfGoodsAndServicesSold4.10.00.03.10.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.41.21.40.41.10.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:ElectricityPurchasedAffiliates so:AlabamaPower0.00.00.00.00.00.0

so:ElectricityPurchasedAffiliates, so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value129150134176206178
Percentage of CostOfGoodsAndServicesSold29.40.00.025.70.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.62.52.63.33.33.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:ElectricityPurchasedAffiliates so:GeorgiaPower0.00.00.00.00.00.0

srt:Fuel, so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value215248310301273356
Percentage of CostOfGoodsAndServicesSold49.00.00.043.90.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax4.35.05.25.65.15.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Fuel so:AlabamaPower0.00.00.00.00.00.0

srt:Fuel, so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value231312443299429480
Percentage of CostOfGoodsAndServicesSold52.60.00.043.60.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax4.66.37.45.58.07.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Fuel so:GeorgiaPower0.00.00.00.00.00.0

srt:Fuel, so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value79881219393116
Percentage of CostOfGoodsAndServicesSold18.00.00.013.60.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.61.82.01.71.71.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Fuel so:MississippiPower0.00.00.00.00.00.0

srt:Fuel, so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value107128166145188190
Percentage of CostOfGoodsAndServicesSold24.40.00.021.10.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.12.62.82.73.53.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Fuel so:SouthernPower0.00.00.00.00.00.0

us-gaap:ElectricityPurchased, so:AlabamaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value407747376448
Percentage of CostOfGoodsAndServicesSold9.10.00.05.40.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.81.30.90.71.00.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ElectricityPurchased so:AlabamaPower0.00.00.00.00.00.0

us-gaap:ElectricityPurchased, so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value129151124118106111
Percentage of CostOfGoodsAndServicesSold29.40.00.017.20.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.62.52.42.21.72.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ElectricityPurchased so:GeorgiaPower0.00.00.00.00.00.0

us-gaap:ElectricityPurchased, so:MississippiPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value5663117
Percentage of CostOfGoodsAndServicesSold1.10.00.00.40.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.10.10.10.10.20.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ElectricityPurchased so:MississippiPower0.00.00.00.00.00.0

us-gaap:ElectricityPurchased, so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value142632243739
Percentage of CostOfGoodsAndServicesSold3.20.00.03.50.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.30.40.60.40.60.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ElectricityPurchased so:SouthernPower0.00.00.00.00.00.0

us-gaap:NaturalGasUsRegulated, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value43936379191686486104228
Percentage of CostOfGoodsAndServicesSold100.00.00.00.0100.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax8.77.41.33.712.79.11.74.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:NaturalGasUsRegulated so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

Costs And Expenses

us-gaap:CostsAndExpenses



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value3755422439823756172147593985556449964834415670244465459443473274303229903752323932263944352636063572330930382838310737763385315833003861325632353033326629983176
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax74.886.066.473.731.889.264.798.978.485.967.0129.477.488.769.473.476.583.869.574.777.184.970.384.991.765.572.778.784.169.674.978.787.572.677.477.886.469.877.286.6

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value92912291165106810701152117911231101116511241030100610761135101499895311401057105510611149108011271104103510011093987925101311481036991110912091073
Percentage of CostsAndExpenses24.729.129.328.462.224.229.620.222.024.127.014.722.523.426.131.032.931.930.432.632.70.00.00.028.631.328.728.033.032.532.632.630.430.631.433.631.333.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax18.525.019.420.919.821.619.120.017.320.718.119.017.420.818.122.725.226.721.124.425.226.421.524.224.322.024.425.721.623.625.727.421.122.924.729.422.725.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower68.80.00.00.076.00.067.80.00.00.064.60.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value14191496159414701385156216022520144814151512140913311504164413951363126517271462152416141711161417531612149014701574148514011536189317281596159619141589
Percentage of CostsAndExpenses37.835.440.039.180.532.840.245.329.029.336.420.129.832.737.842.645.042.346.045.147.20.00.00.044.445.741.341.247.648.949.449.450.151.050.548.449.648.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax28.330.426.628.825.629.326.044.822.725.124.425.923.129.026.231.334.435.532.033.736.440.232.036.137.732.135.137.731.235.538.941.634.938.239.842.336.037.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower77.80.00.00.075.60.061.80.00.00.059.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2312722772592312572782432954502903257334444343305267387407263252316703254656405694675239219198221272246238227272247
Percentage of CostsAndExpenses6.26.47.06.913.45.47.04.45.99.37.046.47.59.77.99.38.812.910.88.17.80.00.00.016.611.519.318.97.27.27.07.17.27.37.56.97.07.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax4.65.54.65.14.34.84.54.34.68.04.760.05.88.65.56.86.710.87.56.16.07.913.25.714.18.116.417.34.75.25.56.05.05.55.96.05.15.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower83.40.00.00.080.50.077.70.00.00.085.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value889812533555112194311868112519694976201169531
Percentage of CostsAndExpenses23.719.213.414.865.119.83.012.225.020.012.08.826.212.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.716.58.910.920.717.71.912.119.617.28.011.420.38.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas71.20.00.00.076.10.024.00.00.00.088.00.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value287396407357383476499539449446459417385360366292268249272262281346330277291248252238235195197222253218204200245189
Percentage of CostsAndExpenses7.69.410.29.522.310.012.59.79.09.211.05.98.67.88.48.98.88.37.28.18.70.00.00.07.47.07.06.77.16.47.07.26.76.56.56.16.35.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.78.16.87.07.18.98.19.67.07.97.47.76.76.95.86.56.87.05.06.06.78.66.26.26.34.95.96.14.74.75.56.04.74.85.15.34.64.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower76.50.00.00.086.50.078.60.00.00.074.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Operating Income Loss

us-gaap:OperatingIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value126369020131342369157821746313767942045-159413065871917118593357816491098957561127811037007991491640325814174011437665891652113685447014589519214771415886489
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax25.214.033.626.368.210.835.31.121.614.133.0-29.422.611.330.626.623.516.230.525.322.914.023.924.715.120.329.715.18.322.034.527.321.315.930.425.121.312.527.422.622.213.630.222.813.4

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value422134676445338164561380372268616454376252650430333264555398346267520357381312500357307271544390291258523404329204497389
Percentage of OperatingIncomeLoss33.419.433.633.29.228.425.8603.227.033.830.1-28.528.842.933.936.335.745.733.736.236.247.640.732.454.439.033.555.894.533.331.334.138.043.831.735.638.543.434.140.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax8.42.711.38.76.23.19.16.85.84.89.98.46.54.910.49.68.47.410.39.28.36.69.78.08.27.910.08.47.97.310.89.38.17.09.68.98.25.49.39.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower31.20.00.00.024.00.032.20.00.00.035.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value4062051161647448257991-47251347010346395012581054656509376964554454288920572516404872552412400924535344222895537393141714411
Percentage of OperatingIncomeLoss32.129.757.748.212.144.545.6-749.237.359.250.6-40.138.444.055.055.454.665.158.550.547.451.372.051.973.750.658.586.2126.849.153.146.844.937.754.247.346.030.049.043.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax8.14.219.412.78.34.816.1-8.48.18.316.711.88.75.016.814.712.810.517.812.810.97.217.212.811.110.317.413.010.610.818.312.89.56.016.511.99.83.713.49.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower22.20.00.00.024.40.038.20.00.00.040.60.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value46229354565280547-17751-2954-62-1669-28-10-143-661224-70-34956-325-24-79-388-4293166463016533925285529
Percentage of OperatingIncomeLoss3.63.24.64.01.59.03.785.70.5-22.32.5185.3-4.7-28.30.5-2.4-1.1-24.7-4.01.12.5-12.6-27.35.1-46.5-3.1-5.4-60.7-132.03.93.84.13.92.83.23.42.96.03.83.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.90.41.61.11.01.01.31.00.1-3.10.8-54.4-1.1-3.20.1-0.6-0.3-4.0-1.20.30.6-1.8-6.51.3-7.0-0.6-1.6-9.1-11.00.91.31.10.80.41.00.90.60.71.00.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower16.60.00.00.019.50.022.30.00.00.015.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value360318-3513435310437449388110689639118512
Percentage of OperatingIncomeLoss28.546.1-1.710.09.618.017.277.828.213.93.3-6.029.931.50.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax7.26.5-0.62.66.51.96.10.96.12.01.11.86.83.60.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas28.80.00.00.023.90.076.00.00.00.012.00.00.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value88151671536030136166032159112652813481475512975674010451595311655646511990566310886776811158
Percentage of OperatingIncomeLoss7.02.28.311.41.65.26.325.44.44.07.8-7.05.04.87.06.85.09.57.86.87.07.28.24.68.56.77.88.619.98.16.97.97.410.86.67.69.114.67.76.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.80.32.83.01.10.62.20.30.90.62.62.11.10.52.11.81.21.52.41.71.61.02.01.11.31.42.31.31.71.82.42.21.61.72.01.91.91.82.11.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower23.50.00.00.013.50.021.40.00.00.025.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Interest And Debt Expense

us-gaap:InterestAndDebtExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value456442434429430456458470458424416404374293246228218180213206202215211218220211219217199222228225218222220226232225
Percentage of InterestAndDebtExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax9.19.07.28.47.98.57.48.47.27.87.27.86.06.66.26.44.04.25.14.44.05.15.44.35.35.95.94.04.45.56.14.25.25.46.34.86.06.2

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value888883828383828079777578777473697169656763636265656671737375737774767676
Percentage of InterestAndDebtExpense19.319.919.119.119.318.217.917.017.218.218.019.320.625.329.730.332.638.330.50.00.00.030.132.230.231.332.633.234.634.233.638.733.333.233.834.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.81.81.41.61.51.61.31.41.21.41.31.51.21.71.81.91.31.61.61.71.21.41.31.31.51.71.41.72.02.01.31.71.82.01.41.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower6.50.00.00.05.90.04.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value111105103105969495102106104101989899949190938986889084929691959091869071961009587
Percentage of InterestAndDebtExpense24.323.823.724.522.320.620.721.723.124.524.324.326.233.838.239.941.351.741.80.00.00.040.845.544.743.143.640.943.139.341.535.743.243.742.239.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.22.11.72.11.81.81.51.81.71.91.81.91.62.22.42.61.72.12.12.11.62.01.81.82.32.31.92.22.52.31.71.62.42.71.82.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower6.10.00.00.05.20.03.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1617171717171921191719281515161313-301111912128101091376356545
Percentage of InterestAndDebtExpense3.53.83.94.04.03.74.14.54.14.04.66.94.05.16.55.76.0-16.75.20.00.00.05.84.34.84.94.55.93.72.91.82.82.72.32.22.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.30.30.30.30.30.30.30.40.30.30.30.50.20.30.40.40.2-0.70.30.30.20.30.30.20.20.30.20.30.20.20.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower5.80.00.00.05.90.05.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-31
Value5858565959585259594846
Percentage of InterestAndDebtExpense12.713.112.913.813.712.711.412.612.911.311.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.21.20.91.21.11.10.81.00.90.90.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas4.60.00.00.04.00.010.60.00.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value394243414445454647485039352221151823222222212212202017131320191718171819
Percentage of InterestAndDebtExpense8.69.59.99.610.29.99.89.810.311.312.09.79.47.58.56.68.312.810.30.00.00.010.76.49.69.77.96.36.59.59.28.98.57.78.48.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.80.90.70.80.80.80.70.80.70.90.90.80.60.50.50.40.30.50.50.50.40.50.50.30.50.50.30.30.40.60.40.40.50.50.40.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower10.40.00.00.09.90.07.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value10313619978-81577860-5711-3-6-5521-29-21-21-21-12-8-7-10-4-6113-2-37-1-42-39-14-9-136-10-3-13
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.10.31.01.91.4-1.50.91.40.9-1.00.2-0.1-0.1-1.10.3-0.7-0.5-0.6-0.4-0.3-0.2-0.2-0.2-0.1-0.20.00.3-0.1-1.0-0.0-0.10.0-1.1-0.3-0.2-0.30.2-0.2-0.1-0.4

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2410111114-49125-6-51-5-5-5-4-8-23-7-14-4-173-3-502-1-7-4-7-10-7-7-6-12-7-5
Percentage of OtherNonoperatingIncomeExpense23.376.918.011.117.94.915.815.48.310.5-45.5-33.383.39.1-23.813.838.1109.533.3116.750.00.00.00.071.4-0.0-50.016.7-700.0-30.8350.027.0700.0175.0-300.030.148.354.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.50.20.20.20.3-0.10.10.20.1-0.1-0.10.0-0.1-0.1-0.1-0.1-0.2-0.6-0.1-0.3-0.1-0.40.1-0.1-0.10.00.0-0.0-0.1-0.1-0.2-0.3-0.1-0.2-0.1-0.3-0.1-0.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower1.80.00.00.01.00.00.50.00.00.0-0.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value522736354011303538-851620311817271810-2211-2-11-2-1-6-3-3-4-5-1-5-5-1
Percentage of OtherNonoperatingIncomeExpense50.5207.759.035.451.3-13.652.644.963.314.045.5-533.3-333.3-5.552.4-27.6-81.0-128.6-85.7-8.3-0.00.00.00.028.610.0-25.033.3-100.0-46.2150.08.1400.0125.0-50.012.634.510.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.00.50.60.70.70.20.50.60.6-0.10.10.30.30.10.20.20.40.80.30.00.0-0.50.00.0-0.0-0.00.0-0.1-0.0-0.1-0.1-0.1-0.1-0.1-0.0-0.1-0.1-0.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower2.80.00.00.02.20.01.20.00.00.00.20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value8-3455-110271-5-11-1-3-1-1-2-3-2-1-2-2-7-1-10-2-12000000010
Percentage of OtherNonoperatingIncomeExpense7.8-23.16.65.16.413.60.034.61.78.8-9.1-33.316.75.5-4.83.49.514.39.58.325.00.00.00.025.73.856.525.8244.1-4.112.1-1.9-25.715.3-20.1-1.2-7.6-6.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.2-0.10.10.10.1-0.20.00.50.0-0.1-0.00.0-0.0-0.1-0.0-0.0-0.1-0.1-0.0-0.0-0.0-0.1-0.1-0.0-0.0-0.0-0.1-0.00.0-0.0-0.00.00.0-0.0-0.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower2.90.00.00.01.70.00.00.00.00.0-0.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value94565-2063121318359
Percentage of OtherNonoperatingIncomeExpense8.730.88.26.16.424.710.53.820.0-22.8163.6-100.0-83.342.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.20.10.10.10.1-0.40.10.10.20.20.30.10.10.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas0.70.00.00.00.30.01.20.00.00.03.20.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2-1640211723-232-13212011005000-100000000000
Percentage of OtherNonoperatingIncomeExpense1.9-7.79.840.42.6-1.229.82.65.03.527.3-66.716.7-5.59.5-3.4-9.5-0.0-4.8-8.3-0.00.00.00.0-1.77.942.34.3-52.2-1.5-1.52.315.86.53.01.11.43.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.0-0.00.10.80.00.00.30.00.0-0.00.00.0-0.00.10.00.00.10.00.00.00.0-0.00.1-0.00.0-0.0-0.0-0.0-0.0-0.00.0-0.0-0.0-0.00.0-0.0-0.0-0.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower0.50.00.00.00.50.02.70.00.00.00.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value9863351712107634191201845-26610493241699-193598023916169087194151470945799
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax19.66.828.621.163.22.230.0-4.716.55.827.4-35.617.04.625.820.418.111.627.221.819.1

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3686761738828396504326311198546386304174575358262204491329292211475302324442302248474321220182454331258128427319
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest37.320.036.036.18.380.027.3-122.629.661.132.1-19.931.072.835.639.436.449.233.434.836.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax7.31.410.37.65.21.88.25.84.93.58.87.15.33.49.28.06.65.79.17.67.05.38.96.87.08.87.16.49.47.76.14.98.47.36.43.48.07.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower27.20.00.00.020.10.029.00.00.00.031.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3471281094577392174926-53944535293455142016396756543231289246238019684649343679046432584345226315682748332178648359
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest35.238.263.953.611.5145.050.2202.642.4108.655.0-28.542.968.259.862.260.175.260.748.947.60.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.92.618.211.37.23.315.0-9.67.06.315.110.17.33.115.412.710.98.716.510.79.14.915.811.09.415.710.98.316.710.87.34.215.210.78.02.112.28.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower19.00.00.00.021.40.035.70.00.00.036.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value383804244246160-11-20264-2934-47-16324-141-130-526639-55-33378-301-56-372-41576473420573822255224
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest3.90.94.73.91.320.03.3-22.6-1.0-62.33.8151.6-4.8-68.21.5-1.50.1-31.3-3.57.04.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.80.11.30.80.80.41.01.1-0.2-3.61.0-54.0-0.8-3.10.4-0.30.0-3.6-1.01.50.9-1.4-6.31.8-6.5-1.1-8.8-10.61.51.10.90.61.10.80.60.71.00.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower13.70.00.00.015.30.017.00.00.00.018.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value354307-51112347673622438374678038911
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest35.991.6-3.010.410.155.819.6-9.036.522.83.9-4.139.70.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax7.16.2-0.92.26.41.35.90.46.01.31.11.56.70.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas28.30.00.00.023.50.073.60.00.00.011.90.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value51-2813015218-14108-2816-171156614-81016028401125345188729371023244101754222886858509239
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest5.2-8.47.614.10.5-11.75.910.51.5-5.26.8-3.41.4-3.36.26.63.99.67.65.65.60.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.0-0.62.23.00.3-0.31.8-0.50.3-0.31.91.20.2-0.21.61.30.71.12.11.21.10.41.60.70.82.00.81.12.01.81.20.61.61.51.51.31.70.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower13.60.00.00.04.10.017.00.00.00.018.60.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-277-355-301-266-272-458-329-329-327-470-346-341-326-348-301-277-214-163-179-153-158-156-154-169-197-178-175-182-216-176-167-185-200-183-177-175-144-173-165-180
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-5.5-7.2-5.0-5.2-5.0-8.6-5.3-5.8-5.1-8.3-5.6-6.3-5.6-6.7-4.8-6.2-5.4-4.6-3.3-3.5-3.8-3.4-3.1-4.0-5.1-3.5-4.2-5.0-5.8-3.2-3.7-4.6-5.3-3.4-4.2-4.2-4.1-3.7-4.3-4.9

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value-54-67-59-57-55-68-57-54-61-70-70-68-72-78-75-72-71-60-64-69-54-56-45-55-57-58-55-59-70-69-71-76-69-73-71-76-70-70
Percentage of NonoperatingIncomeExpense19.518.919.621.420.214.817.316.418.714.920.219.922.122.424.926.033.236.835.845.134.20.00.00.036.537.732.529.939.339.439.035.239.243.738.438.038.239.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-1.1-1.4-1.0-1.1-1.0-1.3-0.9-1.0-1.0-1.2-1.1-1.3-1.2-1.5-1.2-1.6-1.8-1.7-1.2-1.6-1.3-1.4-0.8-1.2-1.2-1.2-1.3-1.5-1.4-1.7-2.0-2.1-1.3-1.6-1.8-2.0-1.3-1.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower-4.00.00.00.0-3.90.0-3.30.00.00.0-4.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value-59-78-67-70-56-83-65-67-68-117-100-88-81-95-87-91-77-64-72-92-74-92-74-79-80-82-88-87-81-83-81-66-68-54-72-63-66-52
Percentage of NonoperatingIncomeExpense21.322.022.326.320.618.119.820.420.824.928.925.824.827.328.932.936.039.340.260.146.80.00.00.051.353.252.144.245.547.444.530.638.632.338.931.536.029.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-1.2-1.6-1.1-1.4-1.0-1.6-1.1-1.2-1.1-2.1-1.6-1.6-1.4-1.8-1.4-2.0-1.9-1.8-1.3-2.1-1.8-2.3-1.4-1.8-1.7-1.6-2.1-2.2-1.6-2.0-2.2-1.8-1.3-1.2-1.8-1.7-1.2-1.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower-3.20.00.00.0-3.10.0-2.50.00.00.0-3.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value-8-19-13-12-12-28-196-18-24132015315141112145415141522242316141003430-2-2-2-4
Percentage of NonoperatingIncomeExpense2.95.44.34.54.46.15.8-1.85.55.1-3.8-5.9-4.6-0.9-5.0-5.1-5.1-7.4-7.8-35.3-9.50.00.00.0-15.5-15.3-9.7-7.2-6.0-0.4-2.1-1.9-2.20.51.61.51.22.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.2-0.4-0.2-0.2-0.2-0.5-0.30.1-0.3-0.40.20.40.30.10.20.30.30.30.31.20.40.40.30.50.50.50.40.40.20.00.10.10.1-0.0-0.1-0.1-0.0-0.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-2.90.00.00.0-4.20.0-5.30.00.00.03.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-6-12-16-22-6-38-12-25-5-36-1-16-2-1
Percentage of NonoperatingIncomeExpense2.23.45.38.32.28.33.67.61.57.70.34.70.60.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.1-0.2-0.3-0.4-0.1-0.7-0.2-0.4-0.1-0.6-0.0-0.3-0.0-0.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas-0.50.00.00.0-0.40.0-2.40.00.00.0-0.20.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value-37-43-37-1-42-44-28-44-44-49-44-46-51-36-33-21-19-15-17-22-22-22-17-21-21-13-22-20-17-14-13-41-20-18-18-17-19-19
Percentage of NonoperatingIncomeExpense13.412.112.30.415.49.68.513.413.510.412.713.515.610.311.07.68.99.29.514.413.90.00.00.014.08.913.210.510.08.17.519.211.410.810.18.810.411.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.7-0.9-0.6-0.0-0.8-0.8-0.5-0.8-0.7-0.9-0.7-0.8-0.9-0.7-0.5-0.5-0.5-0.4-0.3-0.5-0.5-0.5-0.3-0.5-0.5-0.3-0.5-0.5-0.4-0.3-0.4-1.1-0.4-0.4-0.5-0.5-0.4-0.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower-9.90.00.00.0-9.50.0-4.40.00.00.0-7.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value145-743671451360-149623-139113-175590-5873159448272222118500302274176468158315693292009654334923110044124723567435225167
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.9-1.56.12.825.1-2.810.1-2.51.8-3.19.5-10.85.50.27.26.15.63.39.37.06.63.89.33.70.811.37.95.52.610.07.75.82.78.35.95.71.99.35.84.6

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value84-251448962191276482752161511266522114210379192122113831831191271741199718412684711801319664158119
Percentage of IncomeTaxExpenseBenefit57.933.839.261.44.6-12.820.4-46.072.6-42.936.6-25.740.0722.249.352.246.466.938.440.441.20.00.00.072.237.275.3312.932.338.342.074.033.137.541.663.435.848.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.7-0.52.41.71.10.42.11.11.31.33.52.82.21.33.53.22.62.23.62.82.72.13.42.72.73.52.82.53.63.02.31.93.32.92.41.73.02.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower6.20.00.00.04.40.07.30.00.00.012.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value166255129812262-143931253501991564336521316011233718014069317177166299177124314152924230316911120224116
Percentage of IncomeTaxExpenseBenefit11.0-8.169.589.06.0-1.342.1102.982.3-71.459.3-33.949.5477.881.578.372.194.967.459.651.10.00.00.094.363.9112.0400.055.246.246.043.855.848.448.119.850.746.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.30.14.32.51.50.04.3-2.51.52.25.63.72.70.85.84.84.03.16.24.23.31.75.94.03.66.04.23.26.23.62.61.15.63.72.80.54.22.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower0.90.00.00.04.40.010.10.00.00.013.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value631557-1251413-435324-881-27-75-2-17-10-61-31164-32-13915-129-32-153-169211283181278189
Percentage of IncomeTaxExpenseBenefit4.1-4.14.13.40.583.92.2-9.4-3.5-201.74.1150.1-8.6-833.3-0.4-6.2-4.5-51.7-6.25.31.50.00.00.0-73.6-7.0-97.0-545.63.83.74.24.03.43.63.18.64.23.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.10.10.30.10.1-2.30.20.2-0.16.30.4-16.2-0.5-1.4-0.0-0.4-0.3-1.7-0.60.40.1-0.8-2.60.4-2.8-0.7-3.6-4.30.40.30.20.10.30.30.20.20.40.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower2.20.00.00.02.40.03.90.00.00.07.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value7969-22677-113165510413452311507
Percentage of IncomeTaxExpenseBenefit54.5-93.2-6.04.15.77.450.7-39.692.0-76.68.8-5.347.61.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.61.4-0.40.11.4-0.25.11.01.62.40.80.62.60.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas6.30.00.00.05.20.064.20.00.00.09.20.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-04-302018-03-312018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value7-1519-51-975-38-73-4-50-99-810-39-38-52-29-102-41-2371112-2521-2317414332913-132242028307
Percentage of IncomeTaxExpenseBenefit4.820.35.2-35.2-0.7-50.3-6.152.50.0-44.2462.9-6.66.5-16.5-322.2-22.8-15.1-10.45.90.20.34.40.00.00.01.83.83.147.85.88.96.7-1.86.06.99.028.16.83.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.1-0.30.3-1.0-0.21.4-0.6-1.30.00.0-1.6-14.4-0.6-0.7-0.9-0.6-1.6-0.9-0.60.20.00.00.3-0.60.4-0.10.10.40.10.40.70.70.4-0.00.60.50.50.80.60.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower1.90.00.00.0-2.00.0-6.00.00.00.00.00.0-6.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Taxes Paid Net

us-gaap:IncomeTaxesPaidNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-1611552100351335-1-223-1887-63-133-14143273-289-74-362-43-32-357-1-72795330176295172
Percentage of IncomeTaxesPaidNet100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.30.20.94.10.00.72.20.1-0.0-4.0-3.00.1-0.10.1-0.20.1-3.60.10.16.3-6.9-0.20.1-0.90.1-1.2-0.10.0-8.9-0.0-0.16.60.19.43.87.64.7

dei:LegalEntity

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-12-89-4897-1-158576106055-320054
Percentage of IncomeTaxesPaidNet75.0-809.1-87.346.20.0-451.4433.12120.0-0.0-24.71.6285.7-0.0-415.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.2-1.8-0.81.9-0.0-3.09.41.90.01.0-0.00.40.00.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas-1.00.00.00.0-0.10.0117.10.00.00.0-0.50.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-5-52-191-4221181-211148-39-144-226-116-145-44-73188-303-143-15179-128-32-14-4402100413-4412
Percentage of IncomeTaxesPaidNet31.2-472.7-347.3-201.00.0517.1-158.62960.03900.064.6120.2-1657.116.71500.0338.5-2433.3-133.3-7575.0-4766.7-55.3-27.30.00.00.0635.3-4.5-8.0541.0-0.2-152.9679.012.5-111.4-31.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.1-1.1-3.2-8.30.03.4-3.42.6-0.6-2.6-3.6-2.1-0.00.9-0.7-1.64.7-8.5-2.6-3.51.9-3.2-0.6-0.3-1.0-0.00.10.30.00.10.3-1.10.10.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower-1.30.00.00.00.20.0-33.20.00.00.0-36.60.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value841409134593120592691222-1279364991109-1348665230116863649729797064352536886931397993639384277933620438169833526510265806494141
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax16.88.322.418.338.05.019.8-2.314.78.917.9-24.811.54.418.614.312.58.318.014.812.67.917.37.42.519.715.310.77.517.213.710.94.515.712.512.37.617.212.73.9

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value284924732992217737726222912333023517810935421615912529920717912829218319726818315129019513611127420016264269200
Percentage of ProfitLoss33.822.535.232.110.728.630.9-206.324.524.629.8-17.426.847.430.334.032.042.130.832.234.10.00.00.053.530.858.5155.729.230.535.440.129.432.337.037.832.338.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.71.97.95.94.11.46.14.73.62.25.34.33.12.15.74.84.03.55.54.84.33.25.54.14.25.34.33.95.74.73.83.05.04.44.01.75.14.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower21.00.00.00.015.70.021.70.00.00.019.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value331122839448311172664-39635222758435226412060235227220055528224012752931627049128720152930017111452431421058424243
Percentage of ProfitLoss39.429.862.448.115.163.954.3311.837.645.552.7-26.139.752.251.555.354.767.357.243.945.70.00.00.073.456.591.7207.253.346.944.541.256.250.647.934.250.946.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.62.514.08.85.73.210.8-7.05.54.09.46.54.62.39.67.96.95.610.36.55.73.29.97.15.89.86.85.210.57.24.73.19.76.95.21.58.05.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower18.10.00.00.017.00.025.60.00.00.022.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3206537371494747-7-55540-2053-20-8826311-69-215035-23-19462-171-23-218-24555352516382515163415
Percentage of ProfitLoss3.80.04.84.01.855.43.8-37.0-0.7-111.23.6152.3-3.0-38.32.20.52.2-23.2-2.27.86.70.00.00.0-46.6-2.7-69.9-253.55.55.56.76.04.14.13.49.84.13.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.60.01.10.70.72.80.80.8-0.1-9.90.6-37.8-0.3-1.70.40.10.3-1.9-0.41.20.8-0.6-3.61.4-3.7-0.5-5.2-6.31.10.80.70.50.70.60.40.40.60.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower11.60.00.00.012.90.013.10.00.00.011.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value275238-291062707846-31279-6015492394
Percentage of ProfitLoss32.758.2-2.211.413.129.03.824.429.8-12.01.4-3.635.90.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.54.8-0.52.15.01.50.7-0.64.4-1.10.20.94.10.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas22.00.00.00.018.30.09.30.00.00.02.70.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value44-1311120327-60146451157931541046620203101513311152334365323485272968462923564437226231
Percentage of ProfitLoss5.2-3.28.321.81.3-22.311.9-35.412.3158.913.9-7.79.98.717.415.910.311.111.48.16.30.00.00.09.39.88.930.16.97.37.68.66.07.28.613.27.56.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.9-0.31.94.00.5-1.12.40.81.814.12.51.91.10.43.22.31.30.92.11.20.81.11.20.70.71.70.70.71.41.10.80.61.01.00.90.61.20.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower11.70.00.00.06.10.023.00.00.00.024.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value821399127586420842521175-1429684881078-13836492421161620
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax16.48.121.316.938.54.719.1-2.515.28.717.4-25.511.24.718.513.9

dei:LegalEntity

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value4217816652-62922614579512977584219878
Percentage of ComprehensiveIncomeNetOfTax5.10.36.119.22.5-24.67.8-18.315.0162.912.0-5.68.917.417.112.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.80.01.33.31.0-1.21.50.52.314.12.11.41.00.83.21.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower11.20.00.00.011.70.014.50.00.00.020.90.00.00.00.00.0

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value794130489620591233-1159661118-1350649115260937127694465149335385430285976616374231897608426155819514503245794486134
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax15.821.817.638.020.0-2.015.218.0-24.911.218.413.79.47.717.515.011.87.617.07.12.219.314.710.46.216.513.410.64.115.412.212.17.017.012.53.7

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2854743002223782632303312361793552171581272932121751242921831972681841512781741309825618915453259189
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest35.936.333.510.830.7-228.723.829.6-17.527.630.835.642.646.031.032.635.50.00.00.055.831.460.9177.628.528.234.842.428.531.136.234.231.636.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.77.95.94.16.14.73.65.34.33.15.74.94.03.65.44.94.23.15.54.14.25.34.33.95.54.23.62.74.74.23.81.44.94.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower21.10.00.015.821.70.00.019.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value330804421312665-39535358535326560335327320154529722612352931727049228720252629516811052130920756422241
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest41.661.747.015.253.9343.536.552.3-26.140.852.358.073.672.857.745.645.80.00.00.076.557.695.0237.653.947.944.947.658.150.848.636.151.546.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.613.48.35.810.8-7.05.59.46.54.69.67.96.95.610.16.85.43.19.97.15.89.86.85.210.47.14.73.09.66.85.21.57.95.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower18.10.00.017.025.60.00.023.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value326537374747-839-2053-1926311-69-215035-23-19463-171-23-218-24554352416282514163315
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest4.05.04.11.83.8-40.9-0.83.5152.1-2.92.30.53.0-25.0-2.27.77.10.00.00.0-48.6-2.7-72.3-289.05.65.76.67.13.24.23.410.44.13.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.61.10.70.70.80.8-0.10.6-37.8-0.30.40.10.3-1.9-0.41.20.8-0.6-3.61.4-3.7-0.5-5.1-6.31.10.80.70.40.50.60.40.40.60.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower11.60.00.012.913.10.00.011.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-30
Value260-3210326952-3028115482371
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest32.7-2.511.513.14.226.129.11.3-3.636.50.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.2-0.52.05.00.8-0.54.40.20.94.10.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas20.80.00.018.210.60.00.02.70.00.00.0

so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value111031952314649139159995819878513510246334463303385293070483025574640226531
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest1.47.921.81.111.8-42.614.414.2-7.38.917.212.813.712.710.87.16.70.00.00.09.510.09.836.37.27.88.211.16.47.69.414.78.06.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.21.73.80.42.40.92.22.61.81.03.21.71.31.01.91.10.81.11.20.70.71.70.70.81.41.20.80.71.11.01.00.61.20.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower2.90.00.05.223.00.00.025.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss

Net Income Loss Available To Common Stockholders Basic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value868409131689920842691164-1549384961069-1381658197113061248527195962950828371861135141485229781383976623368261916604422153817510494249789478125
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.38.322.017.638.55.018.9-2.714.78.817.2-25.411.43.818.013.712.27.617.814.512.17.013.413.77.610.517.07.02.110.319.314.910.27.116.913.410.54.115.412.111.97.116.912.33.4

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value280884692962177337325922511932523017410235021115512129520016911928217318714025817314111328018512610226419015255259190
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic32.321.535.632.910.427.132.0-168.224.024.030.4-16.726.451.831.034.532.044.630.831.833.342.039.328.353.333.830.358.2174.129.528.729.734.239.128.831.536.035.931.737.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.61.87.85.84.01.46.14.63.52.15.24.23.02.05.64.73.93.45.54.64.03.05.33.94.03.65.14.13.63.15.54.43.52.84.94.23.81.54.94.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower20.70.00.00.015.40.021.40.00.00.018.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value331122839448311173664-39635222758034726011359834726819655127723612352531126620848728219718152529516711052030920654420238
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic38.129.863.849.814.964.357.0257.137.545.854.3-25.139.557.452.956.755.372.357.544.046.543.573.150.975.850.257.294.9243.247.353.847.445.442.156.851.248.835.351.446.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.62.514.08.85.73.210.8-7.05.54.09.46.44.52.29.57.86.85.510.26.45.63.19.87.05.75.39.76.65.14.910.47.14.63.09.66.85.11.47.95.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower18.10.00.00.017.00.025.60.00.00.022.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3206537371494746-7-55640-2054-20-8926211-71-214935-24-19562-17212-24-219-2463354352516382514163315
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic3.70.04.94.11.855.44.0-29.9-0.7-112.13.7148.7-3.0-45.22.30.32.3-26.2-2.27.86.9-8.5-27.210.2-49.03.1-2.8-73.8-304.18.75.65.66.96.24.24.23.510.64.13.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.60.01.10.70.72.80.80.8-0.1-9.90.6-37.8-0.3-1.70.40.00.3-2.0-0.41.10.8-0.6-3.71.4-3.70.3-0.5-5.2-6.30.91.10.80.70.40.70.60.40.40.60.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower11.60.00.00.012.90.013.10.00.00.011.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value275238-291062707846-31279-6015492391104
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic31.758.2-2.211.813.029.04.020.129.7-12.11.4-3.536.355.80.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.54.8-0.52.15.01.50.7-0.64.4-1.10.20.94.12.10.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas22.00.00.00.018.30.09.30.00.00.02.70.00.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value75-128617456-609222121795124827023176895034102463344633033238527293068462923564437
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic8.6-2.96.519.42.7-22.37.9-14.312.9160.311.6-5.910.611.715.614.510.312.510.67.36.515.78.95.09.55.610.09.436.08.17.07.58.09.16.17.48.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.5-0.21.43.41.0-1.11.50.41.914.12.01.51.20.42.82.01.31.01.91.10.81.11.20.70.70.61.70.70.70.81.41.10.80.61.01.00.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower20.00.00.00.012.60.014.50.00.00.020.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-3-7-4-9-23-33002-211-1
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic-0.3-1.7-0.3-1.0-0.11.1-0.3-1.90.00.00.20.10.20.5-0.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.1-0.1-0.1-0.2-0.00.1-0.00.10.00.00.0-0.00.00.0-0.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:IntersegmentElimination0.00.00.00.00.00.06.80.00.00.0-5.00.00.00.00.0

us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:OperatingSegments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value274271301032738368-8
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic31.666.32.311.513.130.95.85.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.55.50.52.05.01.61.1-0.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, so:ElectricUtilities, so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value7586174569222121
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic8.66.519.42.77.9-14.312.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.51.43.41.01.50.41.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:ElectricUtilities so:SouthernPower0.00.00.00.00.00.00.0

us-gaap:OperatingSegments, so:ElectricUtilities, so:TraditionalElectricOperatingCompanies



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value64213737825651148-48
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic74.0104.387.027.198.631.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.822.915.310.418.6-0.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:ElectricUtilities so:TraditionalElectricOperatingCompanies0.00.00.00.00.00.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, so:SouthernCompanyGas



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302016-09-30
Value275-2910627046-3127915494
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic31.7-2.211.813.04.020.129.71.4-3.50.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.5-0.52.15.00.7-0.64.40.20.90.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:SouthernCompanyGas0.00.00.00.09.30.00.02.70.00.0

us-gaap:OperatingSegments, us-gaap:AllOtherSegments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-30
Value-121-110-1541195-119-100-74-80-68-84-62
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic-13.9-8.4-17.157.3-10.264.9-7.9-7.54.9-12.8-5.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-2.4-1.8-3.022.1-1.9-1.8-1.2-1.3-1.3-1.5-1.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments us-gaap:AllOtherSegments0.00.00.00.0-58.90.00.0-52.30.00.00.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments, dei:LegalEntity

us-gaap:OperatingSegments, so:GasDistributionOperations, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value1641093758133447468
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic18.926.72.86.56.416.46.4-44.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax3.32.20.61.12.50.81.21.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:GasDistributionOperations so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, so:GasMarketingServices, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value5729-4-36131-8-76
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic6.67.1-0.3-0.32.911.5-0.749.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.10.6-0.1-0.11.10.6-0.1-1.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:GasMarketingServices so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, so:GasPipelineInvestments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value303162532352021
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic3.57.60.52.81.513.01.7-13.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.60.60.10.50.60.70.30.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:GasPipelineInvestments so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, so:WholesaleGasServices, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value23102-92347-27-18-21
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic2.624.9-0.72.62.3-10.0-1.513.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.52.1-0.20.50.9-0.5-0.3-0.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments so:WholesaleGasServices so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, us-gaap:AllOtherSegments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value1-33-593-3-5-22-23
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic0.1-8.1-4.50.3-0.1-1.9-1.914.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.0-0.7-1.00.1-0.1-0.1-0.4-0.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments us-gaap:AllOtherSegments so:SouthernCompanyGas0.00.00.00.00.00.00.00.0

us-gaap:ProductOrService

so:ElectricUtilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-30
Value71723314599566213581240-26733-1360502180119468451430897660751028472261135185029695977596369271918603423170818505496260793452
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic82.657.0110.9106.329.8133.1106.516.978.198.576.391.4105.7111.8106.0113.7101.896.5100.4100.4100.6100.0100.099.899.7117.3100.195.7100.3103.8100.299.8100.2111.1100.199.0100.3104.4100.494.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax14.34.724.318.811.56.720.1-0.511.5-25.08.73.519.115.313.08.618.114.012.27.113.513.77.616.97.02.419.414.310.27.316.913.310.54.515.412.011.97.416.911.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:ElectricUtilities0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value868131689920841164-154938
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.322.017.638.518.9-2.714.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.0

us-gaap:StatementEquityComponents, dei:LegalEntity

so:CommonStockholdersEquityNotIncludingNoncontrollingInterest, so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value7586174569222121
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic8.66.519.42.77.9-14.312.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.51.43.41.01.50.41.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:CommonStockholdersEquityNotIncludingNoncontrollingInterest so:SouthernPower0.00.00.00.00.00.00.0

us-gaap:RetainedEarnings, so:AlabamaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value280469296217373259225
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic32.335.632.910.432.0-168.224.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.67.85.84.06.14.63.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:RetainedEarnings so:AlabamaPower0.00.00.00.00.00.00.0

us-gaap:RetainedEarnings, so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value331839448311664-396352
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic38.163.849.814.957.0257.137.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.614.08.85.710.8-7.05.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:RetainedEarnings so:GeorgiaPower0.00.00.00.00.00.00.0

us-gaap:RetainedEarnings, so:MississippiPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value326537374746-7
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic3.74.94.11.84.0-29.9-0.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.61.10.70.70.80.8-0.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:RetainedEarnings so:MississippiPower0.00.00.00.00.00.00.0

us-gaap:RetainedEarnings, so:SouthernCompanyGas



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value275-2910627046-31279
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic31.7-2.211.813.04.020.129.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.5-0.52.15.00.7-0.64.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:RetainedEarnings so:SouthernCompanyGas0.00.00.00.00.00.00.0

us-gaap:RetainedEarnings, so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value7586174569222121
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic8.66.519.42.77.9-14.312.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.51.43.41.01.50.41.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:RetainedEarnings so:SouthernPower0.00.00.00.00.00.00.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-31-362529-29-135423-6-23022-4-3271211400017171616171616161716161616161616161616
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.6-0.70.40.6-0.5-0.20.90.4-0.1-0.00.50.4-0.1-0.10.40.30.00.40.00.00.00.40.30.40.40.30.40.40.40.30.40.40.40.30.40.40.50.30.40.4

dei:LegalEntity

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-31-362529-29-125423-6-23022-4-327121-196001100000
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.092.3100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0-7.10.00.00.00.00.00.04.80.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.6-0.70.40.6-0.5-0.20.90.4-0.1-0.00.50.4-0.1-0.10.40.30.0-0.00.20.10.0-0.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower-8.30.00.00.0-6.50.08.50.00.00.04.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets

us-gaap:Assets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value11885211870011759111486711409611691411171711277711156711100511031510868410976010969710636290873787357831875215741817161070923676546640064838645466469763961632746314961963608975987459267573435602355019550325489453374525805204648347
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value29368291522901928067274072673026610262702431723864237892313322869225162245722156219772172121633212202075620552202931953019362192511935218838187691871218826185541866418477185151823017994
Percentage of Assets24.724.624.724.424.022.923.823.321.821.521.621.320.820.521.124.427.927.728.828.629.029.030.029.429.929.829.929.529.729.630.430.531.231.232.332.532.7
Percentage of Assets24.724.624.724.424.022.923.823.321.821.521.621.320.820.521.124.427.927.728.828.629.029.030.029.429.929.829.929.529.729.630.430.531.231.232.332.532.7
Percentage of Assets so:AlabamaPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value45179445414441543239425384036536861359613719936779371063618835248348353424834015328023286531726317483151631030299152966929189289072920729127289952880328421280782733727151267052646925914
Percentage of Assets38.037.537.837.637.334.533.031.933.333.133.633.332.131.832.237.441.742.042.242.844.043.844.244.745.044.845.145.545.845.645.946.145.745.846.647.247.1
Percentage of Assets38.037.537.837.637.334.533.031.933.333.133.633.332.131.832.237.441.742.042.242.844.043.844.244.745.044.845.145.545.845.645.946.145.745.846.647.247.1
Percentage of Assets so:GeorgiaPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value4860503549464874478548864817465347124866505555318088823581657987791678407913794769476756631163645827584854725438540554515119461443223671284025722476
Percentage of Assets4.14.24.24.24.24.24.34.14.24.44.65.17.47.57.78.810.110.010.510.79.79.59.39.69.09.18.58.58.58.68.37.67.26.25.04.64.5
Percentage of Assets4.14.24.24.24.24.24.34.14.24.44.65.17.47.57.78.810.110.010.510.79.79.59.39.69.09.18.58.58.58.68.37.67.26.25.04.64.5
Percentage of Assets so:MississippiPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2161721687210472076120952214482039822112225682298722190218092168321853
Percentage of Assets18.218.317.918.118.418.318.319.620.220.720.120.119.819.9
Percentage of Assets18.218.317.918.118.418.318.319.620.220.720.120.119.819.9
Percentage of Assets so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value13646143001439714518151041488315355154281518215206146481470314681151691235111082899989057040622655645549460846054403442944494139385837793781378535963580375735363437
Percentage of Assets11.512.012.212.613.212.713.713.713.613.713.313.513.413.811.612.211.411.49.48.47.87.86.86.96.86.96.96.56.16.06.16.26.06.06.66.36.2
Percentage of Assets11.512.012.212.613.212.713.713.713.613.713.313.513.413.811.612.211.411.49.48.47.87.86.86.96.86.96.96.56.16.06.16.26.06.06.66.36.2
Percentage of Assets so:SouthernPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity

us-gaap:VariableInterestEntityPrimaryBeneficiary, so:SPSolarHoldingsILP, so:SouthernPower



Period End2020-03-312019-12-31
Value63006400
Percentage of Assets5.35.4
Percentage of Assets5.35.4
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary so:SPSolarHoldingsILP so:SouthernPower100.0100.0

us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312015-12-312014-12-312013-12-31
Value-948-1148-1159-1286-1370-1778-1869-1791-1547-1619-1532-1624-1061-312-304
Percentage of Assets-0.8-1.0-1.0-1.1-1.2-1.5-1.7-1.6-1.4-1.5-1.4-1.5-1.4-0.4-0.5
Percentage of Assets-0.8-1.0-1.0-1.1-1.2-1.5-1.7-1.6-1.4-1.5-1.4-1.5-1.4-0.4-0.5
Percentage of Assets us-gaap:IntersegmentElimination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, dei:LegalEntity

us-gaap:IntersegmentElimination, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value-11455-11300-11023-11533-11582-14039
Percentage of Assets-9.6-9.5-9.4-10.0-9.9-12.6
Percentage of Assets-9.6-9.5-9.4-10.0-9.9-12.6
Percentage of Assets us-gaap:IntersegmentElimination so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value219782222821641213602191824300
Percentage of Assets18.518.718.418.618.721.9
Percentage of Assets18.518.718.418.618.721.9
Percentage of Assets us-gaap:OperatingSegments so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:ProductOrService

us-gaap:IntersegmentElimination, so:ElectricUtilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-31
Value-695-713-756-783-779-306-325-317-306-316-440-425-396-397-404-131-101
Percentage of Assets-0.6-0.6-0.6-0.7-0.7-0.3-0.3-0.3-0.3-0.3-0.4-0.5-0.5-0.5-0.5-0.2-0.2
Percentage of Assets-0.6-0.6-0.6-0.7-0.7-0.3-0.3-0.3-0.3-0.3-0.4-0.5-0.5-0.5-0.5-0.2-0.2
Percentage of Assets us-gaap:IntersegmentElimination so:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, so:ElectricUtilities, so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value136461430014397145181510414883
Percentage of Assets11.512.012.212.613.212.7
Percentage of Assets11.512.012.212.613.212.7
Percentage of Assets us-gaap:OperatingSegments so:ElectricUtilities so:SouthernPower100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, so:ElectricUtilities, so:TraditionalElectricOperatingCompanies



Period End2020-03-312019-12-312019-09-302019-06-302018-12-31
Value8176581063804937831479382
Percentage of Assets68.868.368.568.267.9
Percentage of Assets68.868.368.568.267.9
Percentage of Assets us-gaap:OperatingSegments so:ElectricUtilities so:TraditionalElectricOperatingCompanies100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-31
Value216172168721047207612095221448203982211222568229872219021853
Percentage of Assets18.218.317.918.118.418.318.319.620.220.720.119.9
Percentage of Assets18.218.317.918.118.418.318.319.620.220.720.119.9
Percentage of Assets us-gaap:OperatingSegments so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:AllOtherSegments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-31
Value346735113569334333913285308637072733255222752474
Percentage of Assets2.93.03.02.93.02.82.83.32.42.32.12.3
Percentage of Assets2.93.03.02.93.02.82.83.32.42.32.12.3
Percentage of Assets us-gaap:OperatingSegments us-gaap:AllOtherSegments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments, dei:LegalEntity

us-gaap:OperatingSegments, so:GasDistributionOperations, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value181661820417798173971726619358
Percentage of Assets15.315.315.115.114.817.4
Percentage of Assets15.315.315.115.114.817.4
Percentage of Assets us-gaap:OperatingSegments so:GasDistributionOperations so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, so:GasMarketingServices, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value151714961443152715872147
Percentage of Assets1.31.31.21.31.41.9
Percentage of Assets1.31.31.21.31.41.9
Percentage of Assets us-gaap:OperatingSegments so:GasMarketingServices so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, so:GasPipelineInvestments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value165216781743176817631699
Percentage of Assets1.41.41.51.51.51.5
Percentage of Assets1.41.41.51.51.51.5
Percentage of Assets us-gaap:OperatingSegments so:GasPipelineInvestments so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, so:WholesaleGasServices, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value64385065766813021096
Percentage of Assets0.50.70.60.61.11.0
Percentage of Assets0.50.70.60.61.11.0
Percentage of Assets us-gaap:OperatingSegments so:WholesaleGasServices so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:AllOtherSegments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-31
Value110941075910429109341111212726
Percentage of Assets9.39.18.99.59.511.5
Percentage of Assets9.39.18.99.59.511.5
Percentage of Assets us-gaap:OperatingSegments us-gaap:AllOtherSegments so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0

us-gaap:ProductOrService

so:ElectricUtilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value9471694650941349204991123939598708585889870678699483359813637784377560743867331170821700636686265683641606377564028631946250162251614866038559213580765654655546545255429354376528355130347468
Percentage of Assets79.779.780.180.179.980.478.579.079.379.378.489.598.999.098.998.898.998.898.898.999.098.899.098.898.898.699.299.298.998.098.699.199.198.799.199.098.698.2
Percentage of Assets79.779.780.180.179.980.478.579.079.379.378.489.598.999.098.998.898.998.898.898.999.098.899.098.898.898.699.299.298.998.098.699.199.198.799.199.098.698.2
Percentage of Assets so:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value8664586650855098344583118875848332885761852188515383956832748248282803800156726256389561754958344637444074478844790441554377042242416914109340607386283795937472377483755836759363033608633989
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets72.973.072.772.672.874.974.676.076.476.776.176.675.175.575.274.071.671.769.968.868.869.270.069.869.368.268.568.668.567.467.868.168.668.468.969.069.370.3

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value19468199061964218947183961896218734185781669116744163981614515947159121577415651154971544815352150901428214115138461323713114130641306512687126691262912583124681262912450122321207211916
Percentage of Liabilities22.523.023.022.722.121.722.521.719.619.719.519.419.319.219.723.327.527.50.00.00.028.50.00.029.429.429.228.328.728.929.829.930.730.731.731.831.6
Percentage of Assets16.416.816.716.516.116.216.816.515.015.114.914.914.514.514.817.219.719.720.420.319.919.920.519.920.220.220.219.820.020.020.320.521.121.021.321.521.7
Percentage of Assets so:AlabamaPower66.368.367.767.567.170.970.470.768.670.268.969.869.770.770.270.670.571.171.071.168.868.768.267.867.767.967.567.367.567.566.867.267.767.466.166.266.2

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value29667294762965128923282692604223010232592377924848248332420923332232132271722814216472188020705210292084420343196221968119288190501934219533194711926418776187461808917862171201719916907
Percentage of Liabilities34.234.034.734.734.029.727.627.127.929.229.629.128.328.028.433.938.438.90.00.00.041.00.00.043.242.943.243.644.144.044.445.044.044.044.345.344.8
Percentage of Assets25.024.825.225.224.822.320.620.621.322.422.522.321.321.221.425.127.527.927.528.329.128.729.029.629.729.529.930.530.830.530.330.830.230.129.930.730.7
Percentage of Assets so:GeorgiaPower65.766.266.866.966.564.562.464.763.967.666.966.966.266.666.367.166.066.665.366.266.165.665.666.366.165.966.267.167.266.966.166.866.265.864.165.065.2

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value3138338333073257317532773341322233283475310836255129525955045353551054485577566647174639425741613843363837083856381236213570324530892589185516981706
Percentage of Liabilities3.63.93.93.93.83.74.03.83.94.13.74.46.26.46.98.09.89.70.00.00.09.40.00.08.68.28.38.68.68.38.57.87.56.44.84.54.5
Percentage of Assets2.62.92.82.82.82.83.02.93.03.12.83.34.74.85.25.97.07.07.47.66.66.56.36.35.95.65.76.06.05.75.85.35.24.43.23.03.1
Percentage of Assets so:MississippiPower64.667.266.966.866.467.169.469.270.671.461.565.563.463.967.467.069.669.570.571.367.968.767.565.466.062.267.870.970.566.469.770.371.570.565.366.068.9

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value1198612181116541200212214128781177513051133691396513023125671243912744
Percentage of Liabilities13.814.113.614.414.714.714.115.215.716.415.515.115.115.4
Percentage of Assets10.110.39.910.410.711.010.511.612.012.611.811.611.311.6
Percentage of Assets so:SouthernCompanyGas55.456.255.457.858.360.057.759.059.260.858.757.657.458.3

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value7095767877047700788675998054785486248708874688388815933078737437571155984289406535523538297830072811283628482602232622492252229421232108228921092171
Percentage of Liabilities8.28.99.09.29.58.79.79.210.110.210.410.610.711.39.811.110.110.00.00.00.07.10.00.06.36.46.45.85.35.15.35.55.25.25.95.65.8
Percentage of Assets6.06.56.66.76.96.57.27.07.77.87.98.18.08.57.48.27.37.15.75.55.05.04.44.54.34.44.44.13.73.63.63.83.53.64.03.83.9
Percentage of Assets so:SouthernPower52.053.753.553.052.251.152.550.956.857.359.760.160.061.563.767.163.562.960.965.363.863.864.665.363.964.064.062.960.359.559.660.659.058.960.959.663.2

us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity

us-gaap:VariableInterestEntityPrimaryBeneficiary, so:OtherVariableInterestEntities, so:SouthernPower



Period End2020-03-312019-12-31
Value109104
Percentage of Liabilities0.10.1
Percentage of Assets0.10.1
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary so:OtherVariableInterestEntities so:SouthernPower9.99.5

us-gaap:VariableInterestEntityPrimaryBeneficiary, so:SPSolarHoldingsILP, so:SouthernPower



Period End2020-03-312019-12-31
Value382381
Percentage of Liabilities0.40.4
Percentage of Assets0.30.3
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary so:SPSolarHoldingsILP so:SouthernPower6.16.0

us-gaap:VariableInterestEntityPrimaryBeneficiary, so:SPWind, so:SouthernPower



Period End2020-03-312019-12-31
Value123128
Percentage of Liabilities0.10.1
Percentage of Assets0.10.1
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary so:SPWind so:SouthernPower4.95.1

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value1188521187001175911148671140961169141117171127771115671110051103151086841097601096971063629087378735783187092364838645466469763961632746314961963608975987459267573435602355019550325489453374525805204648347
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value29368291522901928067274072673026610262702431723864237892313322869225162245722156219772172121633212202075620552202931953019362192511935218838187691871218826185541866418477185151823017994
Percentage of LiabilitiesAndStockholdersEquity24.724.624.724.424.022.923.823.321.821.521.621.320.820.521.124.427.927.70.00.00.029.00.00.029.929.829.929.529.729.630.430.531.231.232.332.532.7
Percentage of Assets24.724.624.724.424.022.923.823.321.821.521.621.320.820.521.124.427.927.728.828.629.029.030.029.429.929.829.929.529.729.630.430.531.231.232.332.532.7
Percentage of Assets so:AlabamaPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value45179445414441543239425384036536861359613719936779371063618835248348353424834015328023286531726317483151631030299152966929189289072920729127289952880328421280782733727151267052646925914
Percentage of LiabilitiesAndStockholdersEquity38.037.537.837.637.334.533.031.933.333.133.633.332.131.832.237.441.742.00.00.00.043.80.00.045.044.845.145.545.845.645.946.145.745.846.647.247.1
Percentage of Assets38.037.537.837.637.334.533.031.933.333.133.633.332.131.832.237.441.742.042.242.844.043.844.244.745.044.845.145.545.845.645.946.145.745.846.647.247.1
Percentage of Assets so:GeorgiaPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value4860503549464874478548864817465347124866505555318088823581657987791678407913794769476756631163645827584854725438540554515119461443223671284025722476
Percentage of LiabilitiesAndStockholdersEquity4.14.24.24.24.24.24.34.14.24.44.65.17.47.57.78.810.110.00.00.00.09.50.00.09.09.18.58.58.58.68.37.67.26.25.04.64.5
Percentage of Assets4.14.24.24.24.24.24.34.14.24.44.65.17.47.57.78.810.110.010.510.79.79.59.39.69.09.18.58.58.58.68.37.67.26.25.04.64.5
Percentage of Assets so:MississippiPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2161721687210472076120952214482039822112225682298722190218092168321853
Percentage of LiabilitiesAndStockholdersEquity18.218.317.918.118.418.318.319.620.220.720.120.119.819.9
Percentage of Assets18.218.317.918.118.418.318.319.620.220.720.120.119.819.9
Percentage of Assets so:SouthernCompanyGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value13646143001439714518151041488315355154281518215206146481470314681151691235111082899989057040622655645549460846054403442944494139385837793781378535963580375735363437
Percentage of LiabilitiesAndStockholdersEquity11.512.012.212.613.212.713.713.713.613.713.313.513.413.811.612.211.411.40.00.00.07.80.00.06.86.96.96.56.16.06.16.26.06.06.66.36.2
Percentage of Assets11.512.012.212.613.212.713.713.713.613.713.313.513.413.811.612.211.411.49.48.47.87.86.86.96.86.96.96.56.16.06.16.26.06.06.66.36.2
Percentage of Assets so:SouthernPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

Assets Current

us-gaap:AssetsCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value94309817991783528709958393841161995241007292028837842797229658151495461652663705140559957856001593261626696637360416272649555025240588366095524522058735358
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.98.38.47.37.68.28.410.38.59.18.38.17.78.99.116.76.98.39.07.98.78.99.49.49.810.810.510.110.611.39.89.510.712.010.49.911.311.1

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value2610258630862384229719092338229321362006242520792099180521111885192018012206187119231953211915581649169119111629167417572039178719081814206717551822
Percentage of AssetsCurrent27.726.331.128.526.419.924.919.722.419.926.423.524.918.621.912.435.227.60.00.00.030.70.00.032.130.233.027.128.228.530.528.031.628.931.831.931.0
Percentage of Assets2.22.22.62.12.01.62.12.01.91.82.21.91.91.62.02.12.42.32.92.52.72.83.12.32.52.63.02.52.62.83.32.93.23.13.63.13.3
Percentage of Assets so:AlabamaPower8.98.910.68.58.47.18.88.78.88.410.29.09.28.09.48.58.78.310.28.89.39.510.48.08.58.89.98.68.99.410.89.610.29.811.29.610.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value2825279530102517246824742922251334423428268522641981201623262368210125232269251225742428234522992145240726182655264627513118305824482550257924452438
Percentage of AssetsCurrent30.028.530.430.128.325.831.121.636.134.029.225.623.520.724.115.638.538.70.00.00.038.10.00.041.743.045.344.244.644.646.648.040.540.739.744.441.4
Percentage of Assets2.42.42.62.22.22.12.62.23.13.12.42.11.81.82.22.62.73.23.03.43.63.43.53.53.33.74.04.24.24.45.05.04.14.34.54.44.4
Percentage of Assets so:GeorgiaPower6.36.36.85.85.86.17.97.09.39.37.26.35.65.86.87.06.47.77.27.98.27.87.87.77.38.39.09.19.19.611.010.99.09.49.79.29.4

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value3916095905315136287415885615526289849221167567520449531709779659704609607468516492794757654829724854587520430591
Percentage of AssetsCurrent4.16.25.96.45.96.67.95.15.95.56.811.110.912.05.93.48.28.10.00.00.011.10.00.09.19.28.513.212.810.612.411.414.29.48.07.810.0
Percentage of Assets0.30.50.50.50.40.50.70.50.50.50.60.90.81.10.50.60.60.70.91.10.91.00.90.90.70.80.81.21.21.01.31.21.41.00.90.81.1
Percentage of Assets so:MississippiPower8.012.111.910.910.712.915.412.611.911.312.417.811.414.26.96.55.76.89.09.89.510.49.79.58.08.89.014.614.012.016.215.719.816.018.316.723.9

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value17422106153114291811255517023694184823951747166318182250
Percentage of AssetsCurrent18.521.515.417.120.826.718.131.819.423.819.018.821.623.1
Percentage of Assets1.51.81.31.21.62.21.53.31.72.21.61.51.72.1
Percentage of Assets so:SouthernCompanyGas8.19.77.36.98.611.98.316.78.210.47.97.68.410.3

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value11937591134133818477457807736407589047907811757157415773661108577735640627412365394402403307361291283304193204419235262
Percentage of AssetsCurrent12.77.711.416.021.27.88.36.76.77.59.88.99.318.116.310.46.717.00.00.00.09.80.00.07.77.27.05.16.14.74.24.83.23.36.54.34.5
Percentage of Assets1.00.61.01.21.60.60.70.70.60.70.80.70.71.61.51.70.51.40.81.00.90.90.60.60.60.60.60.50.60.50.50.50.30.30.70.40.5
Percentage of Assets so:SouthernPower8.75.37.99.212.25.05.15.04.25.06.25.45.311.612.714.24.112.48.211.811.511.38.97.98.99.19.17.49.47.77.58.05.45.711.26.67.6

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-312008-12-312007-12-312006-12-31
Value216419752931138313611396184719802284213018411433109419752669189775414041109813111271059065968242451562812566591044131515164374104471258266339690606781672417201167
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.81.72.51.21.21.21.71.82.01.91.71.31.01.82.52.11.01.81.51.11.61.00.91.01.10.70.81.02.01.11.72.22.60.80.70.82.30.50.61.30.00.00.00.90.00.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value898894133762375931370268665354495363969642055634344419460919539527366210525229543659651373667835534457616215915436810036828
Percentage of CashAndCashEquivalentsAtCarryingValue41.545.345.645.055.822.438.034.628.625.551.844.663.621.320.818.158.913.854.924.035.538.50.00.042.744.863.913.912.621.829.111.834.026.238.037.138.834.529.237.653.36.7
Percentage of Assets0.80.81.10.50.70.30.60.60.60.50.90.60.60.40.50.40.60.20.80.30.60.41.00.20.40.50.70.10.10.20.60.10.60.61.00.30.30.30.70.20.70.1
Percentage of Assets so:AlabamaPower3.13.14.62.22.81.22.62.62.72.34.02.83.01.92.51.52.00.92.80.91.91.33.30.51.31.52.30.30.30.71.90.41.91.93.10.90.00.90.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value212524491094380111158852266912134712160678524413246346183053297945425188131366211185906514133
Percentage of CashAndCashEquivalentsAtCarryingValue9.82.615.30.70.70.320.60.650.740.014.46.41.90.21.86.48.04.87.73.037.13.40.00.03.14.67.86.815.37.233.828.51.21.04.44.82.71.846.924.42.031.9
Percentage of Assets0.20.00.40.00.00.00.30.01.00.80.20.10.00.00.00.10.10.10.10.00.60.00.10.10.00.00.10.00.10.10.70.30.00.00.10.00.00.01.10.10.00.3
Percentage of Assets so:GeorgiaPower0.50.11.00.00.00.01.00.03.12.30.70.30.10.00.10.40.20.20.30.11.30.10.20.20.10.10.20.10.30.21.50.70.00.00.20.10.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value1002862681992122933792281252482311406224159137589896212134132892458514542119187145216153466211117597516013166522
Percentage of CashAndCashEquivalentsAtCarryingValue4.614.59.114.415.621.020.511.55.511.612.59.80.511.36.07.27.77.08.726.112.118.70.00.014.422.06.228.236.523.117.323.344.716.17.813.718.436.010.52.49.45.4
Percentage of Assets0.10.20.20.20.20.30.30.20.10.20.20.10.00.20.10.20.10.10.10.30.20.20.10.40.10.20.10.20.30.20.30.30.80.40.20.10.10.30.20.00.10.0
Percentage of Assets so:MississippiPower2.15.75.44.14.46.07.94.92.75.14.62.50.12.71.91.70.71.21.22.71.92.01.43.91.52.50.82.23.52.74.23.310.85.84.12.30.06.50.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value311465956576456699473213828194815
Percentage of CashAndCashEquivalentsAtCarryingValue14.42.32.04.04.24.63.03.54.13.41.12.72.61.01.80.8
Percentage of Assets0.30.00.10.00.00.10.10.10.10.10.00.00.00.00.00.0
Percentage of Assets so:SouthernCompanyGas1.40.20.30.30.30.30.30.30.40.30.10.20.10.10.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-312008-12-31
Value33027936837013318119214282129178999310991091102253830161220237486231296842147528163216205661404737
Percentage of CashAndCashEquivalentsAtCarryingValue15.214.112.626.89.813.010.47.23.66.19.76.98.555.640.953.97.059.114.527.12.110.50.00.021.910.46.23.514.74.61.30.60.31.313.61.41.53.20.01.81.09.1
Percentage of Assets0.30.20.30.30.10.20.20.10.10.10.20.10.11.01.01.10.11.10.20.30.00.10.10.00.20.10.10.00.10.00.00.00.00.00.40.00.00.00.00.00.00.1
Percentage of Assets so:SouthernPower2.42.02.62.50.91.21.30.90.50.81.20.70.67.28.89.20.69.32.33.50.41.31.90.52.91.60.90.42.00.80.40.10.10.55.50.20.00.40.00.00.00.0

Inventory L I F O Reserve

Other Assets Current

us-gaap:OtherAssetsCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value17918820813813216223217228621120920624923016871907150703933356074606659461005153596640524951
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.10.10.10.20.20.30.20.20.20.20.20.20.10.10.10.10.10.10.10.10.10.10.10.10.10.10.20.10.10.10.10.10.10.10.1

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value373024262118811390578119101010910459161363314131181211111010
Percentage of OtherAssetsCurrent20.716.011.518.815.911.13.46.41.042.72.43.43.24.85.414.111.114.10.00.00.010.00.00.018.615.49.18.623.317.618.312.120.323.911.019.616.9
Percentage of Assets0.00.00.00.00.00.00.00.00.00.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets so:AlabamaPower0.10.10.10.10.10.10.00.00.00.40.00.00.00.00.00.00.00.00.00.00.00.00.00.10.10.00.00.00.10.10.10.00.10.10.10.10.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value697710158487091233915272238388955619294868574118821085475484810411181841061445280
Percentage of OtherAssetsCurrent38.541.048.642.036.443.239.213.413.67.112.910.715.316.553.077.567.8129.60.00.00.0148.00.00.0154.3138.5227.3137.180.0140.5185.0122.7142.4230.4144.0102.0135.6
Percentage of Assets0.10.10.10.10.00.10.10.00.00.00.00.00.00.00.10.10.10.10.10.10.10.10.20.10.20.10.10.10.10.20.20.10.10.20.30.10.1
Percentage of Assets so:GeorgiaPower0.20.20.20.10.10.20.20.10.10.00.10.10.10.10.30.20.20.30.30.30.30.20.40.30.40.20.30.20.20.40.40.30.30.40.50.20.3

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value10109136749298238107581076649139534331756108281919
Percentage of OtherAssetsCurrent5.65.34.39.44.54.31.75.20.74.33.81.01.23.56.09.95.611.30.00.00.012.40.00.019.324.016.099.155.423.29.49.416.919.328.639.232.3
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.10.00.00.00.00.00.00.00.0
Percentage of Assets so:MississippiPower0.20.20.20.30.10.10.10.20.00.20.20.00.00.10.10.10.10.10.10.10.10.10.10.10.20.20.10.60.60.30.10.10.20.21.00.80.8

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value4341434442508842512825201611
Percentage of OtherAssetsCurrent24.021.820.731.931.830.937.924.417.813.312.09.76.44.8
Percentage of Assets0.00.00.00.00.00.00.10.00.00.00.00.00.00.0
Percentage of Assets so:SouthernCompanyGas0.20.20.20.20.20.20.40.20.20.10.10.10.10.1

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-312015-09-302015-06-302014-12-312011-12-312011-09-302011-06-302010-12-31
Value24433833373729313536262631393231301916210000
Percentage of OtherAssetsCurrent13.422.918.323.928.022.812.518.012.217.112.412.612.417.019.043.742.30.00.042.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets so:SouthernPower0.20.30.30.20.20.20.20.20.20.20.20.20.20.30.30.30.30.30.30.40.00.00.00.0

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value105931105114103529103428102673103706100672996261044991035421020141010219977498416941747811276553751187001366369660216479364150635866325161980615776007359744580795781757408567315602955698549095358850618
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets89.188.688.090.090.088.790.188.393.793.392.592.990.989.788.586.097.295.998.7102.4102.3100.1100.3100.5100.2100.0101.1100.3100.8101.3103.2104.3103.1102.1104.4104.4103.0104.7

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value30348300232964829070288103040229568293742752027326266192646626134260312580025572251872475023922238122325423080226882253322234220922191621674215082140721253211102099920809205302039419966
Percentage of PropertyPlantAndEquipmentGross28.628.628.628.128.129.329.429.526.326.426.126.226.226.427.432.732.932.90.00.00.033.00.00.033.533.533.833.833.833.834.334.335.034.835.335.335.2
Percentage of Assets25.525.325.225.325.326.026.526.024.724.624.124.423.823.724.328.132.031.631.832.132.532.533.533.934.334.233.933.934.033.934.334.735.135.135.836.436.3
Percentage of Assets so:AlabamaPower103.3103.0102.2103.6105.1113.7111.1111.8113.2114.5111.9114.4114.3115.6114.9115.4114.6113.9110.6112.2112.0112.3111.8115.4114.8114.8113.2115.1114.6114.4112.9113.8112.5112.6110.9111.9111.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value38436381373740938517380153767535671354673517734861345893441034059338413339433045323183184131546313633142531083308183054530295301322976229672294622924428667285492788427804269182683726397
Percentage of PropertyPlantAndEquipmentGross36.336.336.137.237.036.335.435.633.733.733.934.134.134.435.542.342.242.40.00.00.044.40.00.045.645.645.946.346.346.246.346.446.446.546.346.446.5
Percentage of Assets32.332.131.833.533.332.231.931.431.531.431.431.731.030.831.436.441.040.741.942.343.943.845.646.046.746.746.046.446.646.346.346.946.646.946.947.948.0
Percentage of Assets so:GeorgiaPower85.185.684.289.189.493.396.898.694.694.893.295.196.697.197.597.198.596.999.498.899.7100.2103.0103.0103.8104.2101.9101.9101.6101.5100.9101.7102.0102.4100.8101.4101.9

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value4900485748294800482149004819481647804773483648264963486548354809490548864475445643964378432334923467345833133171307330362981295629122902244524292392
Percentage of PropertyPlantAndEquipmentGross4.64.64.74.64.74.74.84.84.64.64.74.85.04.95.16.26.46.50.00.00.06.30.00.05.25.25.14.94.84.84.84.84.84.94.24.24.2
Percentage of Assets4.14.14.14.24.24.24.34.34.34.34.44.44.54.44.55.36.26.25.96.06.16.26.45.35.35.45.15.04.94.84.84.94.94.94.34.34.3
Percentage of Assets so:MississippiPower100.896.597.698.5100.8100.3100.0103.5101.498.195.787.361.459.159.260.262.062.356.656.163.364.868.554.959.559.160.658.356.955.758.264.167.479.086.194.496.6

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value1645616344160581568015417151771477114504160561583315383148501466014508
Percentage of PropertyPlantAndEquipmentGross15.515.515.515.215.014.614.714.615.415.315.114.714.714.7
Percentage of Assets13.813.813.713.713.513.013.212.914.414.313.913.713.413.2
Percentage of Assets so:SouthernCompanyGas76.175.476.375.573.670.872.465.671.168.969.368.167.666.4

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value132821327013072128621328413271136031340213803137551373413731134931272894918348773872756049604756585656494149424705469642034076403240593714360231583167316231573143
Percentage of PropertyPlantAndEquipmentGross12.512.612.612.412.912.813.513.513.213.313.513.613.512.910.110.710.19.70.00.00.08.10.00.07.17.16.56.46.36.46.05.95.35.35.45.55.5
Percentage of Assets11.211.211.111.211.611.412.211.912.412.412.412.612.311.68.99.29.89.38.08.27.98.07.37.47.37.36.56.46.46.46.05.95.35.35.55.65.7
Percentage of Assets so:SouthernPower97.392.890.888.688.089.288.686.990.990.593.893.491.983.976.875.386.081.785.997.1101.7101.9107.2107.3106.9106.094.598.5104.5107.498.295.287.888.584.289.391.5

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value3118030765304693069330834310383073930255319203145731164306673033029852295902477824566242532405923329230592282122533222192196421906216162132721154208912065720384201741994719647193711912118286
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets26.225.925.926.727.026.527.526.828.628.328.328.227.627.227.827.331.231.033.936.035.735.335.235.134.835.435.535.635.736.436.937.036.736.336.836.836.737.8

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value9608954094659397944799889932981396939563946393549241911290188889879187368623856586278522843083158226811480167916781677617659756274467344724771276931
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment30.831.031.130.630.632.232.332.430.430.430.430.530.530.530.535.935.836.00.00.00.035.40.00.035.335.235.135.135.235.335.035.034.934.734.734.534.4
Percentage of Assets8.18.08.08.28.38.58.98.78.78.68.68.68.48.38.59.811.211.211.511.512.012.012.512.512.712.612.412.412.412.312.412.412.412.412.612.712.6
Percentage of Assets so:AlabamaPower32.732.732.633.534.537.437.337.439.940.139.840.440.440.540.240.140.040.239.940.441.641.541.542.642.542.141.442.041.641.540.740.839.939.739.139.138.5

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1192911753116701214012210120961202911901118181170411655115021144311317112341108711045109031104610961113261122211192110561102810970108421073710574104311053710395102941029610198101379966
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment38.338.238.339.639.639.039.139.337.037.237.437.537.737.938.044.745.045.00.00.00.046.60.00.047.347.647.547.747.647.548.148.148.348.748.849.149.4
Percentage of Assets10.09.99.910.610.710.310.810.610.610.510.610.610.410.310.612.214.013.914.714.815.815.816.516.717.017.016.816.816.716.517.017.117.217.417.818.118.1
Percentage of Assets so:GeorgiaPower26.426.426.328.128.730.032.633.131.831.831.431.832.532.532.832.633.733.234.834.535.936.237.437.337.837.937.136.936.536.237.137.037.737.938.238.338.5

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1489146314501427146714291389136513441325131212831303128912591248128712621215119411941172114911281108109511011098108310651062105210351019988981971
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment4.84.84.84.64.84.64.54.54.24.24.24.24.34.34.35.05.25.20.00.00.04.90.00.04.84.84.84.94.94.94.94.94.94.84.74.84.8
Percentage of Assets1.31.21.21.21.31.21.21.21.21.21.21.21.21.21.21.41.61.61.61.61.71.71.71.71.71.71.71.71.71.71.71.71.71.71.71.81.8
Percentage of Assets so:MississippiPower30.629.129.329.330.729.228.829.328.527.226.023.216.115.715.415.616.316.115.415.017.217.418.217.719.018.720.120.220.019.520.822.824.027.834.838.139.2

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value46514650459045224466440043514293467045964567455044984439
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment14.915.115.114.714.514.214.214.214.614.614.714.814.814.9
Percentage of Assets3.93.93.93.93.93.83.93.84.24.14.14.24.14.0
Percentage of Assets so:SouthernCompanyGas21.521.421.821.821.320.521.319.420.720.020.620.920.720.3

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value2580246423742255228821712087195919891910182316891598148414651374129912481189112510931034981922928871871828808786748710680652628595536
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment8.38.07.87.37.47.06.86.56.26.15.85.55.35.05.05.55.35.10.00.00.04.30.00.04.03.83.83.73.63.63.43.33.23.13.02.92.7
Percentage of Assets2.22.12.02.02.01.91.91.71.81.71.71.61.51.41.41.51.61.61.61.51.51.51.51.41.41.41.31.31.31.21.21.21.11.11.11.11.0
Percentage of Assets so:SouthernPower18.917.216.515.515.114.613.612.713.112.612.411.510.99.811.912.414.414.016.918.119.618.621.320.021.119.719.620.021.020.819.818.818.918.216.716.815.6

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value8396583080817138117481637807977843277192809477987279741786867981178446755546389362552611145486851573512085020049317486874839047274465664585545010437974327942701420024119940630399983923035878
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets70.670.069.570.771.669.170.268.472.672.072.372.472.771.571.070.379.478.077.479.579.377.677.176.976.676.376.576.675.976.477.377.676.375.176.176.175.474.2

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value21807216692131421092220212185121409210701931119010183981811317867177461760017474173051717816741166021607515912155771537415179150581489514679145831443814303142851425514169140841403913865
Percentage of PropertyPlantAndEquipmentNet26.026.126.126.027.027.027.327.323.923.823.123.022.422.623.327.327.728.10.00.00.029.00.00.029.429.429.729.830.029.830.330.731.131.532.232.433.0
Percentage of Assets18.318.318.118.419.318.719.218.717.317.116.716.716.316.216.519.222.021.922.322.422.422.423.023.223.423.323.022.923.022.923.123.523.823.924.625.125.2
Percentage of Assets so:AlabamaPower74.374.373.475.180.381.780.580.279.479.777.378.378.178.878.478.978.779.177.478.277.477.476.878.778.478.277.077.977.777.276.077.076.476.776.177.077.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value33257325893197332119316683096228825282592870928314292362888928369280322760427353268302645625444251342504424666242442397123693234252304622883227392246621981217222156821280209782072120104
Percentage of PropertyPlantAndEquipmentNet39.639.239.139.638.838.336.836.635.535.436.736.735.535.736.542.842.943.30.00.00.045.00.00.045.945.745.946.446.746.446.546.647.047.347.947.947.9
Percentage of Assets28.027.527.228.027.826.525.825.125.725.526.526.625.825.626.030.134.133.833.833.935.034.835.836.136.536.335.635.835.935.635.535.736.035.936.637.036.5
Percentage of Assets so:GeorgiaPower73.673.272.074.374.476.778.278.677.277.078.879.880.580.580.680.481.880.580.279.279.579.581.080.881.281.078.978.678.478.077.377.478.978.478.678.377.6

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value3538352034883486346435743536353935293532359935996230612161015990601858785856580555635366516152894909494945514257427944413996360232002838213419591695
Percentage of PropertyPlantAndEquipmentNet4.24.24.34.34.24.44.54.64.44.44.54.67.87.88.19.49.69.60.00.00.09.80.00.09.59.79.18.68.89.28.57.77.06.34.94.54.0
Percentage of Assets3.03.03.03.03.03.13.23.13.23.23.33.35.75.65.76.67.67.57.87.87.87.67.68.07.67.77.06.76.87.06.45.95.34.83.73.53.1
Percentage of Assets so:MississippiPower72.869.970.571.572.473.173.476.174.972.671.265.177.074.374.775.076.075.074.073.080.179.481.883.184.284.683.278.379.281.578.178.174.077.375.176.268.5

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value1248512307120141178611528113571108010782118971172811412110791078710565
Percentage of PropertyPlantAndEquipmentNet14.914.814.714.514.114.114.114.014.714.714.314.113.513.5
Percentage of Assets10.510.410.210.310.19.79.99.610.710.610.310.29.89.6
Percentage of Assets so:SouthernCompanyGas57.856.757.156.855.053.054.348.852.751.051.450.849.748.3

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value112361132111239110261140511530121021221412448123561233612386122231164296788826797471645837512346134632397140303788383438273647330432983304329932153182315431453035
Percentage of PropertyPlantAndEquipmentNet13.413.613.813.614.014.315.415.815.415.515.515.715.314.812.813.812.711.70.00.00.08.40.00.07.37.57.67.46.86.87.07.17.07.17.27.37.2
Percentage of Assets9.59.59.69.610.09.910.810.811.211.111.211.411.110.69.19.710.19.17.86.96.46.55.96.15.85.95.95.75.25.25.35.45.45.45.55.65.5
Percentage of Assets so:SouthernPower82.379.278.175.975.577.578.879.282.081.384.284.283.376.778.479.688.680.482.982.382.983.586.287.586.086.686.088.185.687.387.487.289.488.983.988.988.3

Long Term Investments

us-gaap:LongTermInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value10178103341052810649105111029610482104271147411510116131156611552114201134033252789275224922407234822752224223021892159215521942118205622322266227120421956206819631988
Percentage of LongTermInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.68.79.09.39.28.89.49.210.310.410.510.610.510.410.73.73.53.53.53.73.63.53.53.53.53.53.53.73.63.64.04.14.13.73.73.93.84.1

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1048121711661157112610391128109610861094105510341003970953929913904872914922906888888864848805776774736724705724675637706687
Percentage of LongTermInvestments10.311.811.110.910.710.110.810.59.59.59.18.98.78.58.427.932.732.80.00.00.036.40.00.035.936.135.434.934.733.633.532.733.031.931.031.630.3
Percentage of Assets0.91.01.01.01.00.91.01.01.01.01.01.00.90.90.91.01.21.21.21.21.31.31.31.31.31.31.21.21.21.21.21.21.21.11.11.31.2
Percentage of Assets so:AlabamaPower3.64.24.04.14.13.94.24.24.54.64.44.54.44.34.24.24.24.24.04.34.44.44.44.54.54.44.24.14.13.93.83.83.93.73.43.93.8

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1049112911091103106599610441037104110411018981957920938923896882861912901885867874876841813798811787773770799774759860930
Percentage of LongTermInvestments10.310.910.510.410.19.710.09.99.19.08.88.58.38.18.327.832.132.00.00.00.035.50.00.036.435.835.735.936.436.035.835.736.436.536.938.541.0
Percentage of Assets0.91.00.91.00.90.90.90.90.90.90.90.90.90.80.91.01.11.11.11.21.31.21.31.31.41.31.31.21.31.21.21.31.31.31.31.51.7
Percentage of Assets so:GeorgiaPower2.32.52.52.62.52.52.82.92.82.82.72.72.72.62.72.72.72.72.72.92.92.92.92.93.02.92.82.72.82.72.72.72.92.92.83.23.6

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value131131136124123242425303028221212121111116665654444444566665
Percentage of LongTermInvestments1.31.31.31.21.20.20.20.20.30.30.20.20.10.10.10.30.40.40.00.00.00.20.00.00.20.20.20.20.20.20.20.30.30.30.30.30.3
Percentage of Assets0.10.10.10.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets so:MississippiPower2.72.62.72.52.60.50.50.50.60.60.60.40.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.20.20.20.2

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value64336356660066296685667466776667771377457897791879327895
Percentage of LongTermInvestments63.261.562.762.263.664.863.763.967.267.368.068.568.769.1
Percentage of Assets5.45.45.65.85.95.76.05.96.97.07.27.37.27.2
Percentage of Assets so:SouthernCompanyGas29.829.331.431.931.931.132.730.234.233.735.636.336.636.1

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value362350354457342345391398404411417423430436391318318319320714848494444454546474748494949494950
Percentage of LongTermInvestments3.63.43.44.33.33.43.73.83.53.63.63.73.73.83.49.611.411.60.00.00.02.00.00.01.91.92.02.12.12.22.22.32.22.32.42.22.2
Percentage of Assets0.30.30.30.40.30.30.30.40.40.40.40.40.40.40.40.30.40.40.40.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets so:SouthernPower2.72.42.53.12.32.32.52.62.72.72.82.92.92.93.22.93.53.64.51.10.90.91.11.01.01.01.01.11.21.31.31.31.41.41.31.41.5

Investments In Affiliates Subsidiaries Associates And Joint Ventures

Goodwill

us-gaap:Goodwill



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-31
Value5280528052805282528453155315531562266268626762716251625162232642
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.44.44.54.64.64.54.84.75.65.65.75.85.75.75.90.30.0

dei:LegalEntity

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value50155015501550155015501550155015592559675967596759675967
Percentage of Goodwill95.095.095.094.994.994.494.494.495.295.295.295.295.595.5
Percentage of Assets4.24.24.34.44.44.34.54.45.35.45.45.55.45.4
Percentage of Assets so:SouthernCompanyGas23.223.123.824.223.923.424.622.726.326.026.927.427.527.3

us-gaap:ConsolidatedEntities

so:PowerSecureInternationalInc.



Period End2020-03-31
Value263
Percentage of Goodwill5.0
Percentage of Assets0.2
Percentage of Assets so:PowerSecureInternationalInc.0.0

us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-31
Value0.00.00.00.0-1000000.00.00.00.00.00.0
Percentage of Goodwill0.00.00.00.0-0.00.00.00.00.00.0
Percentage of Assets0.00.00.00.0-0.00.00.00.00.00.0
Percentage of Assets us-gaap:IntersegmentElimination-0.0-0.0-0.0-0.00.1-0.0-0.0-0.0-0.0-0.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value501550155015501550155015501550155967
Percentage of Goodwill95.095.095.094.994.994.494.494.495.2
Percentage of Assets4.24.24.34.44.44.34.54.45.4
Percentage of Assets us-gaap:OperatingSegments so:SouthernCompanyGas23.223.123.824.223.923.424.622.726.0

us-gaap:OperatingSegments, us-gaap:AllOtherSegments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value263263263265268298298298299
Percentage of Goodwill5.05.05.05.05.15.65.65.64.8
Percentage of Assets0.20.20.20.20.20.30.30.30.3
Percentage of Assets us-gaap:OperatingSegments us-gaap:AllOtherSegments7.67.57.47.97.99.19.78.011.7

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-31
Value523536550550585613674702848873902929935970942490317
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.50.50.50.50.60.60.80.80.80.90.90.90.90.50.4

dei:LegalEntity

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value6570788593101113125264280300320340366
Percentage of IntangibleAssetsNetExcludingGoodwill12.413.114.215.515.916.516.817.831.132.133.334.436.437.7
Percentage of Assets0.10.10.10.10.10.10.10.10.20.30.30.30.30.3
Percentage of Assets so:SouthernCompanyGas0.30.30.40.40.40.50.60.61.21.21.41.51.61.7

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value448461475475510538773798827854860895867415
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.40.40.40.40.50.70.70.70.80.80.80.80.5

dei:LegalEntity

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value6570788593101113125264280300320340366
Percentage of FiniteLivedIntangibleAssetsNet14.515.216.417.918.218.80.00.034.235.136.337.539.540.9
Percentage of Assets0.10.10.10.10.10.10.10.10.20.30.30.30.30.3
Percentage of Assets so:SouthernCompanyGas0.30.30.40.40.40.50.60.61.21.21.41.51.61.7

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

so:PPAFairValueAdjustments



Period End2020-03-312019-12-312018-12-312017-12-312016-12-31
Value316321344409434
Percentage of FiniteLivedIntangibleAssetsNet70.569.663.951.348.5
Percentage of Assets0.30.30.30.40.4
Percentage of Assets so:PPAFairValueAdjustments0.00.00.00.00.0

so:StorageandTransportationContracts



Period End2020-03-312019-12-312018-12-312017-12-312016-12-31
Value12103062
Percentage of FiniteLivedIntangibleAssetsNet0.20.41.93.86.9
Percentage of Assets0.00.00.00.00.1
Percentage of Assets so:StorageandTransportationContracts0.00.00.00.00.0

us-gaap:CustomerRelationships



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value9196101106111129205236
Percentage of FiniteLivedIntangibleAssetsNet20.320.821.322.321.824.025.726.4
Percentage of Assets0.10.10.10.10.10.10.20.2
Percentage of Assets us-gaap:CustomerRelationships0.00.00.00.00.00.00.00.0

us-gaap:OtherIntangibleAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value2345561210
Percentage of FiniteLivedIntangibleAssetsNet0.40.70.81.11.01.11.51.1
Percentage of Assets0.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:OtherIntangibleAssets0.00.00.00.00.00.00.00.0

us-gaap:TradeNames



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value383941474849142153
Percentage of FiniteLivedIntangibleAssetsNet8.58.58.69.99.49.117.817.1
Percentage of Assets0.00.00.00.00.00.00.10.1
Percentage of Assets us-gaap:TradeNames0.00.00.00.00.00.00.00.0

us-gaap:FiniteLivedIntangibleAssetsByMajorClass, dei:LegalEntity

so:PPAFairValueAdjustments, so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302018-12-31
Value316321325311344
Percentage of FiniteLivedIntangibleAssetsNet70.569.668.465.563.9
Percentage of Assets0.30.30.30.30.3
Percentage of Assets so:PPAFairValueAdjustments so:SouthernPower0.00.00.00.00.0

so:StorageandTransportationContracts, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-31
Value124610
Percentage of FiniteLivedIntangibleAssetsNet0.20.40.81.31.9
Percentage of Assets0.00.00.00.00.0
Percentage of Assets so:StorageandTransportationContracts so:SouthernCompanyGas0.00.00.00.00.0

us-gaap:CustomerRelationships, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-31
Value4852576172
Percentage of FiniteLivedIntangibleAssetsNet10.711.312.012.813.4
Percentage of Assets0.00.00.00.10.1
Percentage of Assets us-gaap:CustomerRelationships so:SouthernCompanyGas0.00.00.00.00.0

us-gaap:TradeNames, so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302018-12-31
Value1616171819
Percentage of FiniteLivedIntangibleAssetsNet3.63.53.63.83.5
Percentage of Assets0.00.00.00.00.0
Percentage of Assets us-gaap:TradeNames so:SouthernCompanyGas0.00.00.00.00.0

Intangible Assets Net Including Goodwill

dei:LegalEntity

us-gaap:IntangibleAssetsNetIncludingGoodwill

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value317322326313340345391398404411417423430436319
Percentage of IntangibleAssetsNetIncludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.30.30.30.30.40.40.40.40.40.40.40.4
Percentage of Assets so:SouthernPower2.32.32.32.22.32.32.52.62.72.72.82.92.92.93.6

Deferred Tax Assets Liabilities Net

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value126710711156114112921463143614971653157715131387135713951133833771737904705551586547570549568455451481491479433436458436414395429
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.10.91.01.01.11.31.31.31.51.41.41.31.21.31.10.91.00.91.31.10.90.90.90.90.90.90.70.80.80.90.90.80.80.80.80.80.80.9

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value307269189177193189202212193189178166156163118113109103163156161162142134126142134134128162158144161186193218196
Percentage of OtherAssetsNoncurrent24.225.116.315.514.912.914.114.211.712.011.812.011.511.710.413.614.114.00.00.00.017.90.00.017.925.822.924.522.529.527.831.635.738.739.345.545.0
Percentage of Assets0.30.20.20.20.20.20.20.20.20.20.20.20.10.10.10.10.10.10.20.20.20.20.20.20.20.20.20.20.20.30.30.20.30.30.30.40.4
Percentage of Assets so:AlabamaPower1.00.90.70.60.70.70.80.80.80.80.70.70.70.70.50.50.50.50.80.70.80.80.70.70.70.70.70.70.70.90.80.80.91.01.01.21.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value481500398379379514510570550548608589473417175170157173399446443403294284283246244271279268255221203187213218207
Percentage of OtherAssetsNoncurrent38.046.734.433.229.335.135.538.133.334.740.242.534.929.915.420.420.423.50.00.00.044.60.00.040.144.641.649.548.948.844.948.645.038.943.445.547.5
Percentage of Assets0.40.40.30.30.30.40.50.50.50.50.60.50.40.40.20.20.20.20.50.60.60.60.40.40.40.40.40.40.40.40.40.40.30.30.40.40.4
Percentage of Assets so:GeorgiaPower1.11.10.90.90.91.31.41.61.51.51.61.61.31.20.50.50.50.51.31.41.41.31.01.01.00.90.80.91.00.90.90.80.70.70.80.80.8

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value4834272017316191033232022561018571616071575254473936523436424837302822212
Percentage of OtherAssetsNoncurrent3.83.22.31.81.30.21.11.30.62.11.51.41.64.08.910.29.28.30.00.00.05.80.00.05.76.79.06.36.57.78.68.36.76.04.54.40.5
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.00.00.00.0
Percentage of Assets so:MississippiPower1.00.70.50.40.40.10.30.40.20.70.50.40.30.71.21.10.90.80.80.90.80.80.90.70.70.61.00.60.70.81.00.80.70.80.80.80.1

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value261207189186185193218227232218190186188170
Percentage of OtherAssetsNoncurrent20.619.316.316.314.313.215.215.214.013.812.613.413.912.2
Percentage of Assets0.20.20.20.20.20.20.20.20.20.20.20.20.20.2
Percentage of Assets so:SouthernCompanyGas1.21.00.90.90.90.91.11.01.00.90.90.90.90.8

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value216216207289342373426463600566455410531626355173137139146143113111898772688367423731262926242116
Percentage of OtherAssetsNoncurrent17.020.217.925.326.525.529.730.936.335.930.129.639.144.931.320.817.818.90.00.00.012.30.00.010.312.514.312.37.56.95.65.96.55.55.04.43.8
Percentage of Assets0.20.20.20.30.30.30.40.40.50.50.40.40.50.60.30.20.20.20.20.20.20.20.10.10.10.10.10.10.10.10.10.00.00.00.00.00.0
Percentage of Assets so:SouthernPower1.61.51.42.02.32.52.83.04.03.73.12.83.64.12.91.61.51.62.12.32.02.01.91.91.61.61.91.61.11.00.80.70.80.70.70.60.5

Liabilities Current

us-gaap:LiabilitiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value955312546105341099999191428612965143661363013594126031275112284129171056785147856912989674835553657047346643970146569608863176577565756996037647259945935551555845226
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.010.69.09.68.712.211.612.712.212.211.411.711.211.89.99.410.011.712.67.58.68.811.510.211.110.610.010.611.19.910.211.011.810.911.110.510.710.8

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value170020601455139512421959187616101545140015911431134318981361132413081595179615901689160412241091956932118911361120114316171398158014928678491104
Percentage of LiabilitiesCurrent17.816.413.812.712.513.714.511.211.310.312.611.210.914.712.915.616.617.50.00.00.017.90.00.019.816.820.815.517.416.324.623.025.022.715.314.917.1
Percentage of Assets1.41.71.21.21.11.71.71.41.41.31.41.31.21.71.31.51.72.02.42.12.42.31.81.61.51.41.81.81.81.82.62.32.62.51.51.52.0
Percentage of Assets so:AlabamaPower5.87.15.05.04.57.37.06.16.45.96.76.25.98.46.16.06.07.38.37.58.17.86.05.64.94.86.16.06.06.18.67.58.58.14.74.76.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value3371469749394484387139093474370631303949338336862702347629823151236332953723384043013470285825042096290627483282318136683491323331393141229126043169
Percentage of LiabilitiesCurrent35.337.446.940.839.027.426.825.823.029.026.828.922.026.928.237.030.136.10.00.00.038.70.00.043.452.548.244.749.452.353.153.149.747.840.545.749.0
Percentage of Assets2.84.04.23.93.43.33.13.32.83.63.13.42.53.22.83.53.04.24.95.26.04.94.23.83.24.54.25.15.05.85.65.35.25.34.04.65.8
Percentage of Assets so:GeorgiaPower7.510.511.110.49.19.79.410.38.410.79.110.27.710.08.79.37.210.011.712.113.611.29.68.47.210.19.411.311.012.712.311.511.511.68.69.812.2

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value42973466363463345567670585214631397191421301538978896812183620331677123719781596109796866383310201019990863820861709653558589
Percentage of LiabilitiesCurrent4.55.96.35.86.43.25.24.96.310.811.115.017.311.99.310.510.320.10.00.00.022.10.00.020.012.014.613.915.814.113.113.513.610.811.69.89.1
Percentage of Assets0.40.60.60.60.60.40.60.60.81.31.31.81.91.40.91.01.02.32.72.31.72.82.41.71.51.01.31.61.61.61.41.31.41.21.11.01.1
Percentage of Assets so:MississippiPower8.814.613.413.013.29.314.015.218.130.127.634.626.318.712.011.210.323.425.721.117.829.325.317.216.611.315.218.818.918.216.917.819.919.323.021.723.8

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value18262010158321112306302421713105282034012392223525852918
Percentage of LiabilitiesCurrent19.116.015.019.223.221.216.721.620.725.019.017.521.022.6
Percentage of Assets1.51.71.31.82.02.61.92.82.53.12.22.12.42.7
Percentage of Assets so:SouthernCompanyGas8.49.37.510.211.014.110.614.012.514.810.810.211.913.4

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value1110170412381203101410318135711235123214011627133619031517162813431239916744958947696236120127359543265197272459345331794355428
Percentage of LiabilitiesCurrent11.613.611.810.910.27.26.34.09.19.111.112.810.914.714.419.117.113.60.00.00.010.60.00.02.52.36.37.44.12.84.17.65.55.014.06.26.6
Percentage of Assets0.91.41.11.00.90.90.70.51.11.11.31.51.21.71.41.81.71.61.21.01.31.31.00.40.20.20.60.80.40.30.40.80.60.61.40.60.8
Percentage of Assets so:SouthernPower8.111.98.68.36.76.95.33.78.18.19.611.19.112.512.314.714.913.913.011.917.217.115.15.12.72.98.113.16.95.27.212.19.69.321.110.112.5

Long Term Debt Current

Accounts Payable Current

us-gaap:AccountsPayableCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value16532115189819782037258022462162208925302353192017502228173214931584190515931386137612811467136913871280125312621553135514231315127511601282122913291250
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.41.81.61.71.82.22.01.91.92.32.11.81.62.01.61.62.02.42.22.12.12.02.32.22.22.12.12.12.62.42.52.42.32.12.42.32.62.6

Taxes Payable Current

Accrued Income Taxes Current

us-gaap:AccruedIncomeTaxesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value250179171340656617612525819337513141915111413879138765175113461313877257413197
Percentage of AccruedIncomeTaxesCurrent100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.20.10.30.60.00.20.10.20.20.40.00.00.00.20.20.00.10.10.10.00.10.00.10.00.10.00.00.00.10.00.10.00.4

dei:LegalEntity

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value370017896608677400235026
Percentage of AccruedIncomeTaxesCurrent148.00.00.09.926.210.10.00.00.0666.70.018.419.413.5
Percentage of Assets0.00.00.00.00.10.10.00.10.10.00.00.00.00.0
Percentage of Assets so:SouthernCompanyGas0.20.00.00.10.40.30.00.40.30.20.00.10.20.1

so:SouthernPower



Period End2020-03-312019-12-312019-06-302019-03-312018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value926231162330101354814814799198376571812021710365121710
Percentage of AccruedIncomeTaxesCurrent36.00.013.53.20.90.00.057.428.018.676.739.269.264.31042.10.00.00.047.50.00.02.01.22.618.73.21.256.932.22.519.638.09.710.2
Percentage of Assets0.00.00.00.00.00.20.00.10.00.00.10.10.00.00.30.00.00.10.10.00.00.00.00.00.00.00.00.10.00.00.00.00.00.0
Percentage of Assets so:SouthernPower0.10.20.20.10.01.50.00.70.20.31.01.20.10.12.20.00.11.21.30.20.00.10.00.10.40.00.01.00.10.00.10.50.00.0

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value868830881793754852763808923868752799867683851694564590544358347429465462483426443393426380440493535311362360292219
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.70.70.70.70.70.70.70.80.80.70.70.80.60.80.80.70.80.80.60.50.70.70.70.80.70.70.70.70.70.80.91.00.60.70.70.60.5

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value10910512215597161461435759506371766541393911810511480444039414237383837404038354141
Percentage of OtherLiabilitiesCurrent12.612.713.819.512.918.96.017.76.26.86.67.98.211.17.65.96.96.60.00.00.014.70.00.010.911.89.88.08.27.98.79.010.28.99.29.37.7
Percentage of Assets0.10.10.10.10.10.10.00.10.10.10.00.10.10.10.10.00.00.00.20.10.20.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets so:AlabamaPower0.40.40.40.60.40.60.20.50.20.20.20.30.30.30.30.20.20.20.50.50.50.40.20.20.20.20.20.20.20.20.20.20.20.20.20.20.2

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value233187234383305183180205215198192185241182197299211143345309388204177148160122109140119137131197144139162159134
Percentage of OtherLiabilitiesCurrent26.822.526.648.340.521.523.625.423.322.825.523.227.826.623.143.137.424.20.00.00.037.50.00.044.735.225.430.125.828.430.844.536.632.642.636.125.0
Percentage of Assets0.20.20.20.30.30.20.20.20.20.20.20.20.20.20.20.30.30.20.50.40.50.30.30.20.20.20.20.20.20.20.20.30.20.20.30.30.2
Percentage of Assets so:GeorgiaPower0.50.40.50.90.70.50.50.60.60.50.50.50.70.50.60.90.60.41.11.01.20.70.60.50.50.40.40.50.40.50.50.70.50.50.60.60.5

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value69495252554056746782678922193741557487596144211919212418191816212017182020
Percentage of OtherLiabilitiesCurrent7.95.95.96.67.34.77.39.27.39.48.911.12.52.84.35.99.812.50.00.00.08.20.00.05.56.25.84.04.23.93.94.95.34.14.94.63.8
Percentage of Assets0.10.00.00.00.00.00.10.10.10.10.10.10.00.00.00.00.10.10.10.10.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets so:MississippiPower1.41.01.11.11.10.81.21.61.41.71.31.60.30.20.50.50.70.91.10.70.90.70.30.30.30.40.50.30.40.30.30.50.50.50.70.80.8

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value121128127124160130122143143113112113124108
Percentage of OtherLiabilitiesCurrent13.915.414.415.621.215.316.017.715.513.014.914.114.315.8
Percentage of Assets0.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets so:SouthernCompanyGas0.60.60.60.60.80.60.60.60.60.50.50.50.60.5

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value119132133116111142165146145143586769709769494456531914622121821378818177553
Percentage of OtherLiabilitiesCurrent13.715.915.114.614.716.721.618.115.716.57.78.48.010.211.49.98.77.50.00.00.02.70.00.03.65.35.00.71.71.72.04.34.41.71.51.20.7
Percentage of Assets0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets so:SouthernPower0.90.90.90.80.71.01.10.91.00.90.40.50.50.50.80.60.50.50.80.90.30.30.10.50.30.40.50.10.20.20.20.50.50.20.10.20.1

Long Term Debt

Deferred Tax Liabilities Noncurrent

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value17781814199920582084214720172009220622562139215622342299302224852546258224321446146125482504252625402449240924322442160815631575158023362287229923042057
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.51.71.81.81.81.81.82.02.01.92.02.02.12.82.73.23.33.42.22.33.93.94.04.04.04.04.14.12.82.82.92.94.34.34.44.44.3

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value198206296309302314283275297304289269288300366360377388319308322326203186193195323310319321356339343343323306311
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent11.111.414.815.014.514.614.013.713.513.513.512.512.913.012.114.514.815.00.00.00.013.40.00.013.313.312.712.412.612.614.514.114.114.020.119.619.7
Percentage of Assets0.20.20.30.30.30.30.30.20.30.30.30.20.30.30.30.40.50.50.40.40.40.50.30.30.30.30.50.50.50.50.60.60.60.60.60.50.6
Percentage of Assets so:AlabamaPower0.70.71.01.11.11.21.11.01.21.31.21.21.31.31.61.61.71.81.51.51.61.61.01.01.01.01.71.61.71.71.91.81.81.91.71.71.7

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value497540525550567599650636651659665652673703906901930949893870891903580539541542976941945950922892901905716683684
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent28.029.826.326.727.227.932.231.729.529.231.130.230.130.630.036.336.536.80.00.00.037.10.00.037.437.138.337.637.437.437.637.037.037.144.543.743.3
Percentage of Assets0.40.50.40.50.50.50.60.60.60.60.60.60.60.60.91.01.21.21.21.21.21.30.90.80.80.81.51.51.51.51.51.51.51.51.21.21.2
Percentage of Assets so:GeorgiaPower1.11.21.21.31.31.51.81.81.81.81.81.81.92.02.62.62.82.92.82.72.82.91.91.81.91.93.33.23.33.33.23.23.33.32.72.62.6

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value989910811011111511111211511610911111311514614814915314714614814794949494161158157157163162162161115114113
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent5.55.55.45.35.35.45.55.65.25.15.15.15.15.04.86.05.95.90.00.00.06.10.00.06.56.56.46.36.26.26.76.76.76.67.27.37.2
Percentage of Assets0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.20.20.20.20.20.20.20.10.10.10.10.30.20.20.20.30.30.30.30.20.20.2
Percentage of Assets so:MississippiPower2.02.02.22.32.32.42.32.42.42.42.22.01.41.41.81.91.92.01.91.82.12.21.51.51.61.63.02.92.92.93.23.53.74.44.14.44.6

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value252265353354351357412389413415431432434441
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent14.214.617.717.216.816.620.419.418.718.420.120.019.419.2
Percentage of Assets0.20.20.30.30.30.30.40.30.40.40.40.40.40.4
Percentage of Assets so:SouthernCompanyGas1.21.21.71.71.71.72.01.81.81.81.92.02.02.0

Minority Interest

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value7016095623844054654545166606911048805873880641724754720594568584550508633668641588578514483456508517502391412346330
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.60.50.50.30.40.40.40.50.60.61.00.70.80.80.60.81.00.90.80.90.90.90.81.01.11.01.01.00.90.80.80.90.90.90.70.80.70.7

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value41403332305848647063516970635669787673798879546565615963918175848782926787
Percentage of OtherLiabilitiesNoncurrent5.86.65.98.37.412.510.612.410.69.14.98.68.07.28.79.510.310.60.00.00.013.30.00.011.410.410.712.414.412.111.714.315.116.019.014.716.8
Percentage of Assets0.00.00.00.00.00.00.00.10.10.10.00.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.20.10.2
Percentage of Assets so:AlabamaPower0.10.10.10.10.10.20.20.20.30.30.20.30.30.30.20.30.40.30.30.40.40.40.30.30.30.30.30.30.50.40.40.50.50.40.50.40.5

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value375273228172155139141144148128232206214199203302395331266286268209178171172201177155260308311255254224237228211
Percentage of OtherLiabilitiesNoncurrent53.544.840.644.838.329.931.127.922.418.522.125.624.522.631.741.752.446.00.00.00.035.20.00.030.334.432.230.541.146.148.543.443.943.649.150.040.8
Percentage of Assets0.30.20.20.10.10.10.10.10.10.10.20.20.20.20.20.30.50.40.40.40.40.30.30.30.30.30.30.20.40.50.50.40.40.40.40.40.4
Percentage of Assets so:GeorgiaPower0.80.60.50.40.40.30.40.40.40.30.60.60.60.60.60.91.21.00.80.90.90.70.60.60.60.70.60.50.91.11.10.90.90.80.90.90.8

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value424425221816171614332329362654404140484104328151214555249495252573937303243
Percentage of OtherLiabilitiesNoncurrent6.07.24.45.74.43.43.73.12.14.82.23.64.13.08.45.55.45.60.00.00.04.80.00.02.59.59.69.87.97.98.29.76.97.26.27.28.4
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.00.10.10.10.60.10.00.00.00.00.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets so:MississippiPower0.90.90.50.50.40.30.40.30.30.70.50.50.40.30.70.50.50.50.65.20.60.40.20.20.20.91.00.90.91.01.01.20.91.01.11.31.7

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value3951465063105799610788889188127
Percentage of OtherLiabilitiesNoncurrent5.68.48.213.015.622.617.418.616.212.78.411.310.114.4
Percentage of Assets0.00.00.00.00.10.10.10.10.10.10.10.10.10.1
Percentage of Assets so:SouthernCompanyGas0.20.20.20.20.30.50.40.40.50.40.40.40.40.6

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value234178171169181213259255267322232238288287115105113252216161010878455545431716
Percentage of OtherLiabilitiesNoncurrent33.429.230.444.044.745.857.049.440.546.622.129.633.032.617.914.51.50.40.00.00.02.80.00.01.41.41.50.80.90.90.80.80.91.00.63.73.1
Percentage of Assets0.20.10.10.10.20.20.20.20.20.30.20.20.30.30.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets so:SouthernPower1.71.21.21.21.21.41.71.71.82.11.61.62.01.90.90.90.10.00.40.40.30.30.20.20.20.20.20.10.20.20.10.10.10.10.10.50.5

Stockholders Equity

Common Stock Value

Retained Earnings Accumulated Deficit

Treasury Stock Value

Accumulated Other Comprehensive Income Loss Net Of Tax

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value894900236817697441361232617491509114225111845897632214712508651186298111949131103737118956813052209139199846421116767389031740218401
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.818.339.534.713.725.537.831.123.720.340.534.015.512.234.328.021.833.255.227.521.823.818.928.415.835.340.730.824.912.339.716.117.825.737.25.610.9

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value155308776549146492737497155426739544128414732464339563982307290311724322352270341140490739492327218657
Percentage of NetCashProvidedByUsedInOperatingActivities17.334.232.831.019.636.131.728.410.337.329.429.514.365.534.137.139.247.532.925.731.80.00.00.031.936.628.724.637.533.535.432.846.931.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax3.16.312.910.82.79.212.08.82.47.611.910.02.28.011.710.48.515.818.27.16.97.713.67.27.66.98.23.913.313.610.98.25.812.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower11.50.00.00.010.40.042.40.00.00.042.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value2135421253900212536116169937343299837111116510916065633571386411363295122534449942860331255310686613501401013
Percentage of NetCashProvidedByUsedInOperatingActivities23.860.252.950.928.539.449.940.024.737.839.720.112.426.150.848.565.130.146.534.439.80.00.00.045.258.150.754.942.448.347.535.130.148.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax4.211.020.917.73.910.018.912.45.97.716.16.81.93.217.413.614.210.025.79.58.77.322.97.710.711.014.48.715.019.714.68.73.719.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower11.70.00.00.011.60.044.80.00.00.039.20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-179718283-23148359359-62142226175-40-143235162-25-1764010520422932614632-25430449524667130
Percentage of NetCashProvidedByUsedInOperatingActivities-1.910.87.74.7-3.110.915.420.5-4.112.49.09.5-4.5-22.610.913.0-2.9-14.81.38.822.30.00.00.02.9-3.43.70.13.44.31.86.61.66.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.32.03.01.6-0.42.85.86.4-1.02.53.63.2-0.7-2.83.83.6-0.6-4.90.72.44.95.76.13.30.7-0.61.00.01.21.80.51.70.22.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-6.10.00.00.0-8.00.0100.30.00.00.066.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value6431811824868328-582340978-266-2393758-342
Percentage of NetCashProvidedByUsedInOperatingActivities71.92.05.014.091.82.1-25.019.464.8-23.3-0.121.384.5-15.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.80.42.04.912.60.5-9.46.015.3-4.7-0.07.213.1-5.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas51.50.00.00.046.30.0-118.30.00.00.0-0.40.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value83164502609110-35539-221492605472529670218161-110394358270-1923117783110658444841348710571165
Percentage of NetCashProvidedByUsedInOperatingActivities9.318.221.234.414.8-2.623.2-1.39.922.821.813.710.711.110.212.9-12.733.212.022.6-2.10.00.00.010.08.97.17.86.56.16.310.615.57.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.73.38.411.92.0-0.78.8-0.42.34.68.84.61.71.43.53.6-2.811.06.66.2-0.55.83.31.92.41.72.01.22.32.51.92.61.93.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower22.10.00.00.024.80.084.90.00.00.088.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-889-2319-2075-14522454-2260124-1629-1995-504-1798-2086-2803-3408-3965-10478-2197-2400-2114-1659-1107-1215-1279-1364-1427-1285-834-1180-884-1250-970-947-1088-1462-1051-683-1122
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-17.7-47.2-34.6-28.545.3-42.32.0-28.9-31.3-9.0-29.0-38.4-48.6-65.8-63.3-235.0-55.4-67.3-39.1-38.3-26.5-26.2-32.8-32.6-39.6-34.8-15.4-26.1-22.0-33.1-18.2-22.5-26.2-41.7-22.5-17.6-30.6

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-424-524-437-491-511-689-525-511-564-659-458-430-329-356-341-373-368-439-423-313-313-564-394-354-255-247-229-235-255-177-333-224-251-189
Percentage of NetCashProvidedByUsedInInvestingActivities47.722.621.133.8-20.830.5-423.431.428.3130.825.520.611.710.48.63.616.818.320.018.928.30.00.00.021.019.316.816.519.821.228.225.320.119.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-8.4-10.7-7.3-9.6-9.4-12.9-8.5-9.1-8.9-11.7-7.4-7.9-5.7-6.9-5.4-8.4-9.3-12.3-7.8-7.2-7.5-14.0-7.4-7.9-5.5-6.3-5.5-6.5-6.9-3.3-7.4-5.6-6.7-3.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower-31.40.00.00.0-36.30.0-30.20.00.00.0-26.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-795-1092-959-854-980-896-820-725-668922-509-759-566-589-588-481-689-556-497-486-405-748-541-437-480-479-527-681-502-368-493-428-578-548
Percentage of NetCashProvidedByUsedInInvestingActivities89.447.146.258.8-39.939.6-661.344.533.5-182.928.336.420.217.314.84.631.423.223.529.336.60.00.00.039.537.538.647.739.144.141.848.446.256.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-15.8-22.2-16.0-16.8-18.1-16.8-13.3-12.9-10.516.4-8.2-14.0-9.8-11.4-9.4-10.8-17.4-15.6-9.2-11.2-9.7-18.6-10.1-9.8-10.3-12.3-12.6-18.9-13.6-6.8-10.9-10.7-15.3-10.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower-43.60.00.00.0-53.50.0-31.60.00.00.0-20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-71-65-70-65-63-62-62-56-52-21-122-171-190-188-213-82-214-220-226-227-233-289-316-372-361-352-366-344-327-156-145-52-121-74
Percentage of NetCashProvidedByUsedInInvestingActivities8.02.83.44.5-2.62.7-50.03.42.64.26.88.26.85.55.40.89.79.210.713.721.00.00.00.029.727.626.924.125.518.812.45.99.77.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-1.4-1.3-1.2-1.3-1.2-1.2-1.0-1.0-0.8-0.4-2.0-3.1-3.3-3.6-3.4-1.8-5.4-6.2-4.2-5.2-5.6-7.2-5.9-8.3-7.8-9.0-8.8-9.6-8.9-2.9-3.2-1.3-3.2-1.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-25.60.00.00.0-22.00.0-17.30.00.00.0-35.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-193-397-403-296-290-4511830-20-361-378-411-376-405-1715
Percentage of NetCashProvidedByUsedInInvestingActivities21.717.119.420.4-11.820.01475.81.218.175.022.918.014.443.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-3.8-8.1-6.7-5.8-5.4-8.529.7-0.4-5.7-6.7-6.6-6.9-7.0-27.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas-15.50.00.00.0-19.70.0372.00.00.00.0-72.70.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value600-203-218333-7997-47-124-153-132-100-156-1235-1789-1023-1112-873-1084-884-532-38-526-26-246-14-66-143-47-64-59-119-84-200-80
Percentage of NetCashProvidedByUsedInInvestingActivities-67.58.810.5-22.9-3.2-4.3-37.97.67.726.25.67.544.152.525.810.639.745.241.832.13.40.00.00.01.25.210.63.35.07.210.19.616.08.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.0-4.1-3.66.5-1.51.8-0.8-2.2-2.4-2.3-1.6-2.9-21.4-34.5-16.3-24.9-22.0-30.4-16.4-12.3-0.9-13.1-0.5-5.5-0.3-1.7-3.4-1.3-1.7-1.1-2.6-2.1-5.3-1.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower160.00.00.00.0-17.80.0-7.40.00.00.0-16.20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value1854621256-295-3353527-2576-393629-349-305580102520822590103716821509-57116659643429-210588-221-296-184-151-26-148198-1642-863574976
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax3.79.421.0-5.8-62.09.9-41.8-7.09.9-6.2-4.910.717.840.241.3232.617.242.3-10.63.814.20.911.0-5.016.3-6.0-5.5-4.1-3.8-0.7-2.84.7-0.018.3-18.514.826.6

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value273-227375-194811-192-19647518-17633-171477-194-178-192279-539-145-194145-136227-115-140-95-389106-467-148-156-98-181-200
Percentage of NetCashProvidedByUsedInFinancingActivities147.6-49.129.965.8-24.2-36.47.6-12.082.450.4-10.8-29.546.5-9.3-6.9-1.940.9-35.725.4-116.924.30.00.00.0-325.6-22.1185.218.0211.350.084.864.9685.7134.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.4-4.66.3-3.815.0-3.6-3.20.88.1-3.10.5-3.18.3-3.7-2.8-4.37.0-15.1-2.7-4.53.5-3.44.3-2.6-3.0-2.4-9.32.9-12.6-2.7-3.5-2.4-4.8-3.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower20.20.00.00.057.60.0-11.30.00.00.01.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value742153145-456659228-1121601-768-314458473380-577-64119181-828-314431414-667121-318599369-104-655-15881-14460
Percentage of NetCashProvidedByUsedInFinancingActivities401.133.111.515.3-19.817.5-1.1285.295.5220.1103.079.046.118.3-22.3-0.617.412.0145.0-189.272.30.00.00.0-72.119.8-47.162.847.1221.385.9-53.6545.5-40.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax14.83.12.4-0.912.31.70.5-19.99.4-13.6-5.18.48.27.3-9.2-1.43.05.1-15.3-7.210.310.3-12.52.7-0.72.22.410.2-2.8-12.1-3.52.0-3.81.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower40.70.00.00.036.30.01.10.00.00.0-12.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-98-14-43-315-172-146-200-9-104-13130123960-11993987020030102-1653862694209598376118105-9914269
Percentage of NetCashProvidedByUsedInFinancingActivities-53.0-3.0-3.410.5-0.1-32.65.750.9-1.429.84.322.41.219.00.0-0.029.226.4-12.3120.55.00.00.00.0626.298.0-4.7101.9-170.4-40.2-57.565.8-541.3-46.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-2.0-0.3-0.7-0.60.1-3.2-2.4-3.6-0.1-1.8-0.22.40.27.60.0-0.05.011.21.34.60.72.6-3.18.75.810.80.216.610.22.22.3-2.53.81.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-35.40.00.00.01.70.0-40.80.00.00.0-3.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-18536628747-402431-1261-345-595696396-7-3442090
Percentage of NetCashProvidedByUsedInFinancingActivities-100.079.222.9-15.912.081.849.087.8-94.6-199.4-129.8-1.2-33.680.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-3.77.44.80.9-7.48.1-20.5-6.1-9.312.46.4-0.1-6.033.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas-14.80.00.00.0-27.30.0-256.30.00.00.070.10.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-632-50-286-705-79-73-442206-54-177-368-901331727874192020613594674595282-8757-344760-10-20812432-29142-89
Percentage of NetCashProvidedByUsedInFinancingActivities-341.6-10.8-22.8239.02.4-13.917.2-52.4-8.650.7120.7-15.513.082.933.718.530.290.1-81.8276.50.80.00.00.0-80.811.2-28.7-1.894.3-41.9-17.419.2-539.460.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-12.6-1.0-4.8-13.8-1.5-1.4-7.23.7-0.8-3.1-5.9-1.72.333.314.043.15.238.18.610.60.17.0-1.61.3-0.71.21.4-0.3-5.62.30.7-0.73.8-1.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower-168.50.00.00.0-17.80.0-69.60.00.00.0-59.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value894900236817697441361232617491509114225111845897632214712508651186298111949131103737118956813052209139199846421116767389031740218401
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.818.339.534.713.725.537.831.123.720.340.534.015.512.234.328.021.833.255.227.521.823.818.928.415.835.340.730.824.912.339.716.117.825.737.25.610.9

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value155308776549146492737497155426739544128414732464339563982307290311724322352270341140490739492327218657
Percentage of NetCashProvidedByUsedInOperatingActivities17.334.232.831.019.636.131.728.410.337.329.429.514.365.534.137.139.247.532.925.731.80.00.00.031.936.628.724.637.533.535.432.846.931.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax3.16.312.910.82.79.212.08.82.47.611.910.02.28.011.710.48.515.818.27.16.97.713.67.27.66.98.23.913.313.610.98.25.812.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower11.50.00.00.010.40.042.40.00.00.042.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value2135421253900212536116169937343299837111116510916065633571386411363295122534449942860331255310686613501401013
Percentage of NetCashProvidedByUsedInOperatingActivities23.860.252.950.928.539.449.940.024.737.839.720.112.426.150.848.565.130.146.534.439.80.00.00.045.258.150.754.942.448.347.535.130.148.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax4.211.020.917.73.910.018.912.45.97.716.16.81.93.217.413.614.210.025.79.58.77.322.97.710.711.014.48.715.019.714.68.73.719.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower11.70.00.00.011.60.044.80.00.00.039.20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-179718283-23148359359-62142226175-40-143235162-25-1764010520422932614632-25430449524667130
Percentage of NetCashProvidedByUsedInOperatingActivities-1.910.87.74.7-3.110.915.420.5-4.112.49.09.5-4.5-22.610.913.0-2.9-14.81.38.822.30.00.00.02.9-3.43.70.13.44.31.86.61.66.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-0.32.03.01.6-0.42.85.86.4-1.02.53.63.2-0.7-2.83.83.6-0.6-4.90.72.44.95.76.13.30.7-0.61.00.01.21.80.51.70.22.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-6.10.00.00.0-8.00.0100.30.00.00.066.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value6431811824868328-582340978-266-2393758-342
Percentage of NetCashProvidedByUsedInOperatingActivities71.92.05.014.091.82.1-25.019.464.8-23.3-0.121.384.5-15.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.80.42.04.912.60.5-9.46.015.3-4.7-0.07.213.1-5.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas51.50.00.00.046.30.0-118.30.00.00.0-0.40.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value83164502609110-35539-221492605472529670218161-110394358270-1923117783110658444841348710571165
Percentage of NetCashProvidedByUsedInOperatingActivities9.318.221.234.414.8-2.623.2-1.39.922.821.813.710.711.110.212.9-12.733.212.022.6-2.10.00.00.010.08.97.17.86.56.16.310.615.57.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.73.38.411.92.0-0.78.8-0.42.34.68.84.61.71.43.53.6-2.811.06.66.2-0.55.83.31.92.41.72.01.22.32.51.92.61.93.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower22.10.00.00.024.80.084.90.00.00.088.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value841409134593120592691222-1279364991109-1348665230116863649729797064352536886931397993639384277933620438169833526510265806494141
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax16.88.322.418.338.05.019.8-2.314.78.917.9-24.811.54.418.614.312.58.318.014.812.67.917.37.42.519.715.310.77.517.213.710.94.515.712.512.37.617.212.73.9

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value284924732992217737726222912333023517810935421615912529920717912829218319726818315129019513611127420016264269200
Percentage of ProfitLoss33.822.535.232.110.728.630.9-206.324.524.629.8-17.426.847.430.334.032.042.130.832.234.10.00.00.053.530.858.5155.729.230.535.440.129.432.337.037.832.338.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.71.97.95.94.11.46.14.73.62.25.34.33.12.15.74.84.03.55.54.84.33.25.54.14.25.34.33.95.74.73.83.05.04.44.01.75.14.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower21.00.00.00.015.70.021.70.00.00.019.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value331122839448311172664-39635222758435226412060235227220055528224012752931627049128720152930017111452431421058424243
Percentage of ProfitLoss39.429.862.448.115.163.954.3311.837.645.552.7-26.139.752.251.555.354.767.357.243.945.70.00.00.073.456.591.7207.253.346.944.541.256.250.647.934.250.946.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.62.514.08.85.73.210.8-7.05.54.09.46.54.62.39.67.96.95.610.36.55.73.29.97.15.89.86.85.210.57.24.73.19.76.95.21.58.05.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower18.10.00.00.017.00.025.60.00.00.022.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value3206537371494747-7-55540-2053-20-8826311-69-215035-23-19462-171-23-218-24555352516382515163415
Percentage of ProfitLoss3.80.04.84.01.855.43.8-37.0-0.7-111.23.6152.3-3.0-38.32.20.52.2-23.2-2.27.86.70.00.00.0-46.6-2.7-69.9-253.55.55.56.76.04.14.13.49.84.13.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.60.01.10.70.72.80.80.8-0.1-9.90.6-37.8-0.3-1.70.40.10.3-1.9-0.41.20.8-0.6-3.61.4-3.7-0.5-5.2-6.31.10.80.70.50.70.60.40.40.60.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower11.60.00.00.012.90.013.10.00.00.011.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value275238-291062707846-31279-6015492394
Percentage of ProfitLoss32.758.2-2.211.413.129.03.824.429.8-12.01.4-3.635.90.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.54.8-0.52.15.01.50.7-0.64.4-1.10.20.94.10.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas22.00.00.00.018.30.09.30.00.00.02.70.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value44-1311120327-60146451157931541046620203101513311152334365323485272968462923564437226231
Percentage of ProfitLoss5.2-3.28.321.81.3-22.311.9-35.412.3158.913.9-7.79.98.717.415.910.311.111.48.16.30.00.00.09.39.88.930.16.97.37.68.66.07.28.613.27.56.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.9-0.31.94.00.5-1.12.40.81.814.12.51.91.10.43.22.31.30.92.11.20.81.11.20.70.71.70.70.71.41.10.80.61.01.00.90.61.20.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower11.70.00.00.06.10.023.00.00.00.024.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-889-2319-2075-14522454-2260124-1629-1995-504-1798-2086-2803-3408-3965-10478-2197-2400-2114-1659-1107-1215-1279-1364-1427-1285-834-1180-884-1250-970-947-1088-1462-1051-683-1122
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-17.7-47.2-34.6-28.545.3-42.32.0-28.9-31.3-9.0-29.0-38.4-48.6-65.8-63.3-235.0-55.4-67.3-39.1-38.3-26.5-26.2-32.8-32.6-39.6-34.8-15.4-26.1-22.0-33.1-18.2-22.5-26.2-41.7-22.5-17.6-30.6

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-424-524-437-491-511-689-525-511-564-659-458-430-329-356-341-373-368-439-423-313-313-564-394-354-255-247-229-235-255-177-333-224-251-189
Percentage of NetCashProvidedByUsedInInvestingActivities47.722.621.133.8-20.830.5-423.431.428.3130.825.520.611.710.48.63.616.818.320.018.928.30.00.00.021.019.316.816.519.821.228.225.320.119.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-8.4-10.7-7.3-9.6-9.4-12.9-8.5-9.1-8.9-11.7-7.4-7.9-5.7-6.9-5.4-8.4-9.3-12.3-7.8-7.2-7.5-14.0-7.4-7.9-5.5-6.3-5.5-6.5-6.9-3.3-7.4-5.6-6.7-3.6
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower-31.40.00.00.0-36.30.0-30.20.00.00.0-26.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-795-1092-959-854-980-896-820-725-668922-509-759-566-589-588-481-689-556-497-486-405-748-541-437-480-479-527-681-502-368-493-428-578-548
Percentage of NetCashProvidedByUsedInInvestingActivities89.447.146.258.8-39.939.6-661.344.533.5-182.928.336.420.217.314.84.631.423.223.529.336.60.00.00.039.537.538.647.739.144.141.848.446.256.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-15.8-22.2-16.0-16.8-18.1-16.8-13.3-12.9-10.516.4-8.2-14.0-9.8-11.4-9.4-10.8-17.4-15.6-9.2-11.2-9.7-18.6-10.1-9.8-10.3-12.3-12.6-18.9-13.6-6.8-10.9-10.7-15.3-10.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower-43.60.00.00.0-53.50.0-31.60.00.00.0-20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-71-65-70-65-63-62-62-56-52-21-122-171-190-188-213-82-214-220-226-227-233-289-316-372-361-352-366-344-327-156-145-52-121-74
Percentage of NetCashProvidedByUsedInInvestingActivities8.02.83.44.5-2.62.7-50.03.42.64.26.88.26.85.55.40.89.79.210.713.721.00.00.00.029.727.626.924.125.518.812.45.99.77.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-1.4-1.3-1.2-1.3-1.2-1.2-1.0-1.0-0.8-0.4-2.0-3.1-3.3-3.6-3.4-1.8-5.4-6.2-4.2-5.2-5.6-7.2-5.9-8.3-7.8-9.0-8.8-9.6-8.9-2.9-3.2-1.3-3.2-1.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-25.60.00.00.0-22.00.0-17.30.00.00.0-35.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-193-397-403-296-290-4511830-20-361-378-411-376-405-1715
Percentage of NetCashProvidedByUsedInInvestingActivities21.717.119.420.4-11.820.01475.81.218.175.022.918.014.443.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-3.8-8.1-6.7-5.8-5.4-8.529.7-0.4-5.7-6.7-6.6-6.9-7.0-27.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas-15.50.00.00.0-19.70.0372.00.00.00.0-72.70.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value600-203-218333-7997-47-124-153-132-100-156-1235-1789-1023-1112-873-1084-884-532-38-526-26-246-14-66-143-47-64-59-119-84-200-80
Percentage of NetCashProvidedByUsedInInvestingActivities-67.58.810.5-22.9-3.2-4.3-37.97.67.726.25.67.544.152.525.810.639.745.241.832.13.40.00.00.01.25.210.63.35.07.210.19.616.08.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.0-4.1-3.66.5-1.51.8-0.8-2.2-2.4-2.3-1.6-2.9-21.4-34.5-16.3-24.9-22.0-30.4-16.4-12.3-0.9-13.1-0.5-5.5-0.3-1.7-3.4-1.3-1.7-1.1-2.6-2.1-5.3-1.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower160.00.00.00.0-17.80.0-7.40.00.00.0-16.20.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value156021381933180616782208196520471781218118441910148820581766161418722184125111481091118011971125123114109891040108611929588811054149098610561136
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value340518406443390629532507490671473432306325302332313429326287325491329350287274192244283209272213218202
Percentage of PaymentsToAcquirePropertyPlantAndEquipment21.824.221.024.523.228.527.124.827.530.825.722.620.615.817.120.616.719.626.125.029.80.00.00.024.322.917.119.820.121.126.219.618.321.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value849929869837875840775820681797623728556657508505553770468431422659458446460419336476498432418513562516
Percentage of PaymentsToAcquirePropertyPlantAndEquipment54.443.545.046.352.138.039.440.138.236.533.838.137.431.928.831.329.535.337.437.538.70.00.00.039.035.029.938.735.343.740.247.247.153.9

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value506839504571434133187415118620618920619723119821521327129436832336939237035824021614812170
Percentage of PaymentsToAcquirePropertyPlantAndEquipment3.23.22.02.82.73.22.22.01.90.84.07.912.510.010.712.810.510.615.818.719.50.00.00.027.430.934.930.125.424.320.813.710.27.4

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value261400405347256359350411268421409383301287
Percentage of PaymentsToAcquirePropertyPlantAndEquipment16.718.721.019.215.316.317.820.115.019.322.220.120.216.3

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value472051615766892877121507376694124215147676571941163853555835325438481138881
Percentage of PaymentsToAcquirePropertyPlantAndEquipment3.09.68.33.23.94.01.43.86.82.34.04.04.620.023.831.841.030.115.510.13.50.00.00.00.54.93.12.63.93.94.710.57.48.5

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value1854621256-295-3353527-2576-393629-349-305580102520822590103716821509-57116659643429-210588-221-296-184-151-26-148198-1642-863574976
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax3.79.421.0-5.8-62.09.9-41.8-7.09.9-6.2-4.910.717.840.241.3232.617.242.3-10.63.814.20.911.0-5.016.3-6.0-5.5-4.1-3.8-0.7-2.84.7-0.018.3-18.514.826.6

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value273-227375-194811-192-19647518-17633-171477-194-178-192279-539-145-194145-136227-115-140-95-389106-467-148-156-98-181-200
Percentage of NetCashProvidedByUsedInFinancingActivities147.6-49.129.965.8-24.2-36.47.6-12.082.450.4-10.8-29.546.5-9.3-6.9-1.940.9-35.725.4-116.924.30.00.00.0-325.6-22.1185.218.0211.350.084.864.9685.7134.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax5.4-4.66.3-3.815.0-3.6-3.20.88.1-3.10.5-3.18.3-3.7-2.8-4.37.0-15.1-2.7-4.53.5-3.44.3-2.6-3.0-2.4-9.32.9-12.6-2.7-3.5-2.4-4.8-3.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:AlabamaPower20.20.00.00.057.60.0-11.30.00.00.01.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value742153145-456659228-1121601-768-314458473380-577-64119181-828-314431414-667121-318599369-104-655-15881-14460
Percentage of NetCashProvidedByUsedInFinancingActivities401.133.111.515.3-19.817.5-1.1285.295.5220.1103.079.046.118.3-22.3-0.617.412.0145.0-189.272.30.00.00.0-72.119.8-47.162.847.1221.385.9-53.6545.5-40.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax14.83.12.4-0.912.31.70.5-19.99.4-13.6-5.18.48.27.3-9.2-1.43.05.1-15.3-7.210.310.3-12.52.7-0.72.22.410.2-2.8-12.1-3.52.0-3.81.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:GeorgiaPower40.70.00.00.036.30.01.10.00.00.0-12.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-98-14-43-315-172-146-200-9-104-13130123960-11993987020030102-1653862694209598376118105-9914269
Percentage of NetCashProvidedByUsedInFinancingActivities-53.0-3.0-3.410.5-0.1-32.65.750.9-1.429.84.322.41.219.00.0-0.029.226.4-12.3120.55.00.00.00.0626.298.0-4.7101.9-170.4-40.2-57.565.8-541.3-46.9
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-2.0-0.3-0.7-0.60.1-3.2-2.4-3.6-0.1-1.8-0.22.40.27.60.0-0.05.011.21.34.60.72.6-3.18.75.810.80.216.610.22.22.3-2.53.81.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:MississippiPower-35.40.00.00.01.70.0-40.80.00.00.0-3.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-18536628747-402431-1261-345-595696396-7-3442090
Percentage of NetCashProvidedByUsedInFinancingActivities-100.079.222.9-15.912.081.849.087.8-94.6-199.4-129.8-1.2-33.680.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-3.77.44.80.9-7.48.1-20.5-6.1-9.312.46.4-0.1-6.033.4
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernCompanyGas-14.80.00.00.0-27.30.0-256.30.00.00.070.10.00.00.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-632-50-286-705-79-73-442206-54-177-368-901331727874192020613594674595282-8757-344760-10-20812432-29142-89
Percentage of NetCashProvidedByUsedInFinancingActivities-341.6-10.8-22.8239.02.4-13.917.2-52.4-8.650.7120.7-15.513.082.933.718.530.290.1-81.8276.50.80.00.00.0-80.811.2-28.7-1.894.3-41.9-17.419.2-539.460.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-12.6-1.0-4.8-13.8-1.5-1.4-7.23.7-0.8-3.1-5.9-1.72.333.314.043.15.238.18.610.60.17.0-1.61.3-0.71.21.4-0.3-5.62.30.7-0.73.8-1.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax so:SouthernPower-168.50.00.00.0-17.80.0-69.60.00.00.0-59.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value26533347170122085050060011101549140920531004119979172525550
Percentage of ProceedsFromIssuanceOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value1481656131242911192096128350387060811333848881623606333
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Payments For Repurchase Of Common Stock

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value1481656131242911192096128350387060811333848881623606333
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of LongTermDebtAndCapitalLeaseObligations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Debt Instrument Interest Rate Stated Percentage

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-30
Value0.147-0.02699999999999997-0.03300000000000003-0.0630.398-0.0640.259-0.140.108-0.2930.712-0.6070.321-0.01799999999999996-0.013000000000000012-0.00400000000000000360.308-0.0060000000000000050.006000000000000005-0.0140000000000000120.343-0.0140000000000000120.0060000000000000050.0100000000000000090.3230.245-0.00100000000000000090.342-0.011000000000000010.0070000000000000060.0080000000000000070.3460.00400000000000000360.0130000000000000120.00200000000000000180.316-0.02100000000000002-0.017000000000000015
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312017-09-302014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-312009-09-30
Value0.046-0.011000000000000010.0090000000000000080.0090000000000000080.208-0.042000000000000010.79-0.00300000000000000270.0040000000000000036-0.00200000000000000180.0020000000000000018-0.0100000000000000090.380.381-0.0069999999999999510.3490.0100000000000000090.00200000000000000180.3460.0109999999999999540.0579999999999999960.2780.02200000000000002
Percentage of EffectiveIncomeTaxRateContinuingOperations31.340.7-27.3-14.352.365.6305.01.00.614.333.3-100.0117.6155.5700.0102.0142.925.0100.084.62900.088.0-129.4

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302009-09-30
Value0.135-0.067999999999999980.218999999999999970.14300000000000002-0.4980.2149999999999998611.662-7.3950000000000005-6.47-4.5920.4822.7119999999999997-3.859-0.19700000000000006-0.149000000000000020.09999999999999998-0.840.015-0.068-0.1210.258-0.162999999999999980.141-0.0820.0850.3350.0459999999999999850.3130.006000000000000005-0.00300000000000000270.356-0.0060000000000000050.02100000000000002
Percentage of EffectiveIncomeTaxRateContinuingOperations91.8251.9-663.6-227.0-125.1-335.94502.75282.1-5990.71567.267.7-446.8-1202.21094.41146.2-2500.0-272.7-250.0-1133.3864.375.21164.32350.0-820.026.3136.7-4600.091.585.7-37.5102.9-46.2-123.5

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number

Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period

Deferred Tax Liabilities

Deferred Tax Assets Net

Unrecognized Tax Benefits

Deferred Tax Assets Valuation Allowance

Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value17701800181818621881
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value124132143152160
Percentage of OperatingLeaseRightOfUseAsset7.07.37.98.28.5

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value14011428146114921519
Percentage of OperatingLeaseRightOfUseAsset79.279.380.480.180.8

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value9193929586
Percentage of OperatingLeaseRightOfUseAsset5.15.25.15.14.6

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value368369368370372
Percentage of OperatingLeaseRightOfUseAsset20.820.520.219.919.8

Cash And Cash Equivalents Period Increase Decrease

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value216819782935138613641519189120172290214718581455111619921420
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value8988941337623759313702686653544953639696420194
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents41.445.245.644.955.620.637.134.028.525.351.343.962.421.113.7

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value212524491091123801111588522669121367
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents9.82.615.30.70.77.420.10.550.639.714.36.31.90.24.7

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value100286268199212293379228125248231140622498
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents4.614.59.114.415.519.320.011.35.511.612.49.60.511.26.9

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-06-30
Value31449626061706275100782643332419
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents14.52.52.14.34.54.63.33.74.43.61.43.03.01.20.0

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value330279368370133181192142821401891161101112835
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents15.214.112.526.79.811.910.27.03.66.510.28.09.955.858.8

Proceeds From Repayments Of Short Term Debt

us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity

so:AdditionalConstructionCapitalCosts

so:PlantVogtleUnits3And4, so:CategoryII, so:GeorgiaPower



Period End2020-03-31
Value80
Percentage of AdditionalConstructionCapitalCosts100.0

so:PlantVogtleUnits3And4, so:CategoryIII, so:GeorgiaPower



Period End2020-03-31
Value100
Percentage of AdditionalConstructionCapitalCosts125.0

us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity

so:AdditionalConstructionCapitalCostsThreshold

so:PlantVogtleUnits3And4, so:CategoryI, so:GeorgiaPower



Period End2020-03-31
Value800
Percentage of AdditionalConstructionCapitalCostsThreshold100.0

us-gaap:Range, us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity

srt:Maximum, so:PlantVogtleUnits3And4, so:CategoryII, so:GeorgiaPower



Period End2020-03-31
Value1600
Percentage of AdditionalConstructionCapitalCostsThreshold200.0

srt:Maximum, so:PlantVogtleUnits3And4, so:CategoryIII, so:GeorgiaPower



Period End2020-03-31
Value2100
Percentage of AdditionalConstructionCapitalCostsThreshold262.5

srt:Minimum, so:PlantVogtleUnits3And4, so:CategoryII, so:GeorgiaPower



Period End2020-03-31
Value800
Percentage of AdditionalConstructionCapitalCostsThreshold100.0

dei:LegalEntity

so:AmortizationOfDeferredInvestmentTaxCredits

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value14151410814151415141514141412108754643332
Percentage of AmortizationOfDeferredInvestmentTaxCredits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:CapitalContributionsFromToParentCompany

so:AlabamaPower



Period End2020-03-312019-06-302019-03-312018-09-302018-06-302018-03-31
Value612231236105488
Percentage of CapitalContributionsFromToParentCompany100.0100.0100.0100.0100.0100.0

so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value502382029836291476
Percentage of CapitalContributionsFromToParentCompany82.00.087.02.38360.0580.0302.5

so:MississippiPower



Period End2020-03-312019-06-302019-03-312018-03-31
Value76822
Percentage of CapitalContributionsFromToParentCompany12.434.80.20.4

us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:AdditionalPaidInCapital, so:AlabamaPower



Period End2020-03-312019-06-302019-03-312018-09-302018-06-302018-03-31
Value612231236105488
Percentage of CapitalContributionsFromToParentCompany100.0100.0100.0100.0100.0100.0

us-gaap:AdditionalPaidInCapital, so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value502382029836291476
Percentage of CapitalContributionsFromToParentCompany82.00.087.02.38360.0580.0302.5

us-gaap:AdditionalPaidInCapital, so:MississippiPower



Period End2020-03-312019-06-302019-03-312018-03-31
Value76822
Percentage of CapitalContributionsFromToParentCompany12.434.80.20.4

so:ChangeInConstructionPayables



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-141-37-2539-146-4142161-11213923753-1701381-166-94382-36-96551622-15654100-9913632-96-1528104-1712116
Percentage of ChangeInConstructionPayables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-65284-8-95-45921-5056574350-10-12-1533-76-634-49-322249-1-261441-12-2-11-6
Percentage of ChangeInConstructionPayables46.1-75.7-16.0-20.565.19.8140.513.044.640.324.181.1-2.90.0-1000.07.216.08.6211.166.752.30.00.00.096.1-16.7-118.2-9.07.41.012.1-1.5-33.76.2

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-1015-4-4-8130-7-20-28-190-1-14-4-722-16-1-14-9-112-302327302638-13326-1
Percentage of ChangeInConstructionPayables7.1-40.516.0-10.35.5-31.70.0-4.31.80.0-11.8-35.8-0.0-0.7-1400.02.47.45.844.411.1-21.50.00.00.0-59.8385.8123.7-19.348.539.01.424.582.21.9

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-18-3331251-23-840-46232635-129
Percentage of ChangeInConstructionPayables12.889.2-124.064.1-0.756.1-19.024.841.116.511.066.07.1900.0

so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-09-302011-06-302011-03-312010-09-30
Value-1512-16-71-23251-42-12568-168315021170-303000-574311
Percentage of ChangeInConstructionPayables10.6-48.0-41.04.82.4-14.3-22.30.4-79.273.56800.0101.2-33.0-138.9-233.326.20.00.01.161.7-0.80.6-0.458.131.8-12.3

dei:LegalEntity

so:ChangeInConstructionPayablesNetOfJointOwnerPortion

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-46-47-7033-38-4-14133-474317937-36104-6426-10117318-1137-70-362428-2542-2031574-599394
Percentage of ChangeInConstructionPayablesNetOfJointOwnerPortion100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SubsequentEventType

so:CommonStockConversionPrice

us-gaap:SubsequentEvent



Period End2020-02-292019-02-19
Value68.5949.24
Percentage of CommonStockConversionPrice100.0100.0

us-gaap:PublicUtility, dei:LegalEntity

so:ConstructionFinancingCosts

so:PlantVogtleUnits3And4, so:GeorgiaPower



Period End2020-03-312019-12-312019-09-30
Value2300100100
Percentage of ConstructionFinancingCosts100.0100.0100.0

dei:LegalEntity, us-gaap:StatementScenario

so:ContractWithCustomerLiabilityBillCredits

so:GeorgiaPower, us-gaap:ScenarioForecast



Period End2020-02-292019-06-30
Value10595
Percentage of ContractWithCustomerLiabilityBillCredits100.0100.0

us-gaap:StatementScenario, dei:LegalEntity

srt:ScenarioForecast, so:GeorgiaPower



Period End2020-02-29
Value105
Percentage of ContractWithCustomerLiabilityBillCredits100.0

us-gaap:StatementScenario, dei:LegalEntity

so:CurrentBillingRatesUnderRateECRinTermsofPerUnits

srt:ScenarioForecast, so:AlabamaPower



Period End2021-01-31
Value0.0591
Percentage of CurrentBillingRatesUnderRateECRinTermsofPerUnits100.0

us-gaap:PublicUtility, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity

so:CustomerRefund

so:PlantVogtleUnits3And4, so:TwentyFirstVogtleConstructionMonitoringReport, so:GeorgiaPower



Period End2020-02-18
Value188
Percentage of CustomerRefund100.0

us-gaap:PublicUtility, us-gaap:SubsequentEventType, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity

so:PlantVogtleUnits3And4, us-gaap:SubsequentEvent, so:TwentyFirstVogtleConstructionMonitoringReport, so:GeorgiaPower



Period End2020-02-18
Value188
Percentage of CustomerRefund100.0

so:DepreciationAndAmortizationExcludingNuclearFuel



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value857771760755751793787783769774767754716697695569541519528500487497480476466449445441438431430418376426366343403332377389
Percentage of DepreciationAndAmortizationExcludingNuclearFuel100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value20020019520019919419218918918718518318117917717517216216316015882174172175170159158161160157161160159157155153153
Percentage of DepreciationAndAmortizationExcludingNuclearFuel23.325.925.726.526.524.524.424.124.624.224.124.325.325.725.530.831.831.230.932.032.40.00.00.035.235.433.433.935.936.035.636.837.137.037.641.235.841.7

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value352248250244240233232230228226225223221216215214211213214202216218211209208201204200186185188184180178173132182130
Percentage of DepreciationAndAmortizationExcludingNuclearFuel41.132.232.932.332.029.429.529.429.629.229.329.630.931.030.937.639.041.040.540.444.40.00.00.041.941.942.942.941.441.642.642.041.841.441.435.142.635.5

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value4248484848434244414139414018304538283830272623242222222321222220192019192018
Percentage of DepreciationAndAmortizationExcludingNuclearFuel4.96.26.36.46.45.45.35.65.35.35.15.45.62.64.37.97.05.47.26.05.50.00.00.04.64.64.75.04.75.15.14.74.64.74.85.14.75.1

so:SouthernCompanyGas



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-30
Value120121119118119126129125125120116
Percentage of DepreciationAndAmortizationExcludingNuclearFuel14.015.915.815.715.116.116.816.316.616.816.7

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value117122120119119123130125114124131129119105938173656460595759515141444037343131313030312928
Percentage of DepreciationAndAmortizationExcludingNuclearFuel13.715.815.815.815.815.516.516.014.816.017.117.116.615.113.414.213.512.512.112.012.10.00.00.010.48.69.48.68.47.67.27.27.37.27.28.56.97.9

us-gaap:DisposalGroupClassification, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType, dei:LegalEntity

so:DisposalGroupNotDiscontinuedOperationGainLossonDisposalAfterTax

us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperations, so:Mankato, us-gaap:SubsequentEvent, so:SouthernPower



Period End2020-01-17
Value23
Percentage of DisposalGroupNotDiscontinuedOperationGainLossonDisposalAfterTax100.0

us-gaap:ConsolidatedEntities, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity

so:DistributionMadeToLimitedPartnerCashDistributionsPaidPercentage

us-gaap:VariableInterestEntityPrimaryBeneficiary, so:SPWind, so:FinancialInvestors



Period End2020-03-31
Value0.4
Percentage of DistributionMadeToLimitedPartnerCashDistributionsPaidPercentage100.0

us-gaap:VariableInterestEntityPrimaryBeneficiary, so:SPWind, so:SouthernPower



Period End2020-03-31
Value0.6
Percentage of DistributionMadeToLimitedPartnerCashDistributionsPaidPercentage150.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, dei:LegalEntity

so:SPSolarHoldingsILP, so:GlobalAtlantic



Period End2020-03-312019-12-31
Value0.330.0
Percentage of DistributionMadeToLimitedPartnerCashDistributionsPaidPercentage82.50.0

so:SPSolarHoldingsILP, so:SouthernPower



Period End2020-03-312019-12-31
Value0.670.0
Percentage of DistributionMadeToLimitedPartnerCashDistributionsPaidPercentage167.50.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

so:EquityMethodInvestmentSummarizedFinancialInformationOperatingIncomeLoss

so:SNG



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-09-302017-06-302017-03-31
Value98828610671609960716384
Percentage of EquityMethodInvestmentSummarizedFinancialInformationOperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312014-03-312013-03-312012-06-302012-03-31
Value23-20-1540711-19
Percentage of ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints100.0100.00.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302014-09-302014-06-302014-03-312013-03-31
Value620-262-1-25000011
Percentage of ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints26.1-100.00.013.315.00.00.00.00.00.00.00.00.014.39.1

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-31
Value7-10-4123-2-39-116401030-1145-14
Percentage of ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints30.450.00.026.730.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.057.145.5100.044.4

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312013-03-31
Value3-10-1510-2401
Percentage of ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints13.050.00.06.712.50.00.00.00.00.09.1

so:SouthernPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-31
Value7-20-4133-1-510300010001302
Percentage of ExpectedVolumeOfNaturalGasSubjectToOptionToSellBackExcessGasDueToOperationalConstraints30.4100.00.026.732.50.00.00.00.00.00.00.00.00.00.00.00.014.327.3-0.022.2

so:IncreaseDecreaseInAccruedTaxes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-102-562-25910928-572626292-79-29928980-212394988134-60-56468-257197-44-98212-167-110140169131-426197-7-72-33337944-185
Percentage of IncreaseDecreaseInAccruedTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value100-100141-7280-215917757-243107-2577-1101053464-233194-69246-409106-43147908543-582233160-92-3
Percentage of IncreaseDecreaseInAccruedTaxes-98.017.8-54.4-720.08.637.614.526.4-72.281.337.0-31.2-36.3-27.910.625.4-106.7416.141.526.8124.90.00.00.0-334.1-91.840.1-25.752.715.719.5122.121.6-1.5

so:GeorgiaPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-156-80277106-24532115102-1915314241-23515311598-235-2917992-217-131213101-166-127129-206-3512271-194-35170
Percentage of IncreaseDecreaseInAccruedTaxes152.914.2-106.91060.0-26.4-5.618.434.9241.8-17.749.151.2110.838.811.673.1391.751.838.2-35.8-110.20.00.00.0377.3129.660.8123.431.887.142.0-148.18.285.9

so:MississippiPower



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-54233119-62-1039869-110602046-46-817680-61-35753-5456532-54-4514-314224-31-1111
Percentage of IncreaseDecreaseInAccruedTaxes52.9-4.1-12.0190.0-6.718.015.723.6139.2-20.16.957.521.7-20.67.759.7101.762.516.0-1.2-27.40.00.00.0125.046.46.918.8-4.51.814.8-23.82.85.7

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value27-1-14-752174-1021028134-16-2719-11
Percentage of IncreaseDecreaseInAccruedTaxes-26.50.25.4-750.02.3-12.9-16.33.4-35.4-44.8-5.5-33.8-9.0-1.1

so:SouthernPower



Period End2020-03-312019-12-312019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value8-605-24924169-1347544-4045742199-37516-137-106-42225515484-251924-4723
Percentage of IncreaseDecreaseInAccruedTaxes-7.810.70.543.538.52.1-11.444.826.055.018.9116.042.673.961.7-921.4-29.341.2-2.00.00.00.0-13.3-4.24.2-2.623.014.11.73.711.111.8

dei:LegalEntity

so:IncreaseDecreaseInCustomerRefunds

so:GeorgiaPower



Period End2020-03-312019-03-31
Value-10732
Percentage of IncreaseDecreaseInCustomerRefunds100.0100.0

dei:LegalEntity

so:IncreaseDecreaseRetailFuelCostOverRecoveryShortTerm

so:AlabamaPower



Period End2020-03-312019-03-312018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value-47-20001129365844591-110-569-34-3-25320-21-1
Percentage of IncreaseDecreaseRetailFuelCostOverRecoveryShortTerm100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:IncreaseDecreaseinEnergyRelatedInventoryNaturalGasinStorage



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value-2465206108-36338208118-413-36223188-4114222000
Percentage of IncreaseDecreaseinEnergyRelatedInventoryNaturalGasinStorage100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

dei:LegalEntity

so:SouthernCompanyGas



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-30
Value-2465207107-36338208118-413-36223188-411222
Percentage of IncreaseDecreaseinEnergyRelatedInventoryNaturalGasinStorage100.0100.0100.599.1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

so:IncreaseDecreaseinFairValueofFundsIncludingReinvestedInterestandDividends



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-24727751525814-115055634947
Percentage of IncreaseDecreaseinFairValueofFundsIncludingReinvestedInterestandDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:AlabamaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-1671538873915-52528342629
Percentage of IncreaseDecreaseinFairValueofFundsIncludingReinvestedInterestandDividends67.655.650.757.267.2107.145.550.050.954.053.161.7

so:GeorgiaPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-30
Value-8012376519-1-62527292318
Percentage of IncreaseDecreaseinFairValueofFundsIncludingReinvestedInterestandDividends32.444.449.342.832.8-7.154.550.049.146.046.938.3

us-gaap:StatementScenario, dei:LegalEntity

so:LiabilityForClaimsAndClaimsAdjustmentExpenseAnnualRecoveryAmount

srt:ScenarioForecast, so:AlabamaPower



Period End2021-01-01
Value3
Percentage of LiabilityForClaimsAndClaimsAdjustmentExpenseAnnualRecoveryAmount100.0

so:NoncontrollingInterestIncreasefromContributionsfromNoncontrollingInterestHolders



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value16632312181232292607126118840129138294
Percentage of NoncontrollingInterestIncreasefromContributionsfromNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312014-03-312013-03-31
Value16632312322900
Percentage of NoncontrollingInterestIncreasefromContributionsfromNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value16632312181232292607126118840129138294
Percentage of NoncontrollingInterestIncreasefromContributionsfromNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents, dei:LegalEntity

us-gaap:NoncontrollingInterest, so:SouthernPower



Period End2020-03-312019-06-302019-03-312018-09-302018-06-302018-03-31
Value1623123229
Percentage of NoncontrollingInterestIncreasefromContributionsfromNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity

so:NotionalAmountOfForeignCurrencyDerivativesPayRate

us-gaap:ForeignExchangeContract, so:CashFlowHedgesOfExistingDebt, so:MaturityDateJune2022, so:SouthernPower



Period End2020-03-312019-12-312019-09-30
Value0.02950.00.0
Percentage of NotionalAmountOfForeignCurrencyDerivativesPayRate100.00.00.0

us-gaap:ForeignExchangeContract, so:CashFlowHedgesOfExistingDebt, so:MaturityDateJune2026, so:SouthernPower



Period End2020-03-312019-12-312019-09-30
Value0.03780.00.0
Percentage of NotionalAmountOfForeignCurrencyDerivativesPayRate128.10.00.0

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity

so:NotionalAmountOfForeignCurrencyDerivativesReceiveRate

us-gaap:ForeignExchangeContract, so:CashFlowHedgesOfExistingDebt, so:MaturityDateJune2022, so:SouthernPower



Period End2020-03-312019-12-312019-09-30
Value0.010.00.0
Percentage of NotionalAmountOfForeignCurrencyDerivativesReceiveRate100.00.00.0

us-gaap:ForeignExchangeContract, so:CashFlowHedgesOfExistingDebt, so:MaturityDateJune2026, so:SouthernPower



Period End2020-03-312019-12-312019-09-30
Value0.01850.00.0
Percentage of NotionalAmountOfForeignCurrencyDerivativesReceiveRate185.00.00.0

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity

so:NotionalAmountofInterestRateDerivativesInterestRatePaid

us-gaap:InterestRateContract, so:CashFlowHedgesOfExistingDebt, so:MaturityDateDecember2021, so:MississippiPower



Period End2020-03-31
Value0.0058
Percentage of NotionalAmountofInterestRateDerivativesInterestRatePaid100.0

us-gaap:InterestRateContract, so:CashFlowHedgesOfForecastedDebt, so:MaturityDateSeptember2030, so:SouthernCompanyGas



Period End2020-03-31
Value0.0181
Percentage of NotionalAmountofInterestRateDerivativesInterestRatePaid312.1

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:VariableRate, so:HedgingMaturityDate, dei:LegalEntity

us-gaap:InterestRateContract, so:FairValueHedgesOfExistingDebt, us-gaap:LondonInterbankOfferedRateLIBOR, so:MaturityDateJuly2021, so:SouthernCompany



Period End2020-03-312019-09-30
Value0.00870.0
Percentage of NotionalAmountofInterestRateDerivativesInterestRatePaid150.00.0

us-gaap:InterestRateContract, so:FairValueHedgesOfExistingDebt, us-gaap:LondonInterbankOfferedRateLIBOR, so:MaturityDateJune2020, so:SouthernCompany



Period End2020-03-312019-09-30
Value0.00920.0
Percentage of NotionalAmountofInterestRateDerivativesInterestRatePaid158.60.0

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, so:HedgingMaturityDate, dei:LegalEntity

so:NotionalAmountofInterestRateDerivativesInterestRateReceived

us-gaap:InterestRateContract, so:FairValueHedgesOfExistingDebt, so:MaturityDateJuly2021, so:SouthernCompany



Period End2020-03-312019-09-30
Value0.02350.0
Percentage of NotionalAmountofInterestRateDerivativesInterestRateReceived100.00.0

us-gaap:InterestRateContract, so:FairValueHedgesOfExistingDebt, so:MaturityDateJune2020, so:SouthernCompany



Period End2020-03-312019-12-312019-09-30
Value0.02750.00.0
Percentage of NotionalAmountofInterestRateDerivativesInterestRateReceived117.00.00.0

so:PaymentsPursuantToLongTermServiceAgreements



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value26753628543073577755433349
Percentage of PaymentsPursuantToLongTermServiceAgreements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:LegalEntity

so:MississippiPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-03-31
Value5765154913-2-15
Percentage of PaymentsPursuantToLongTermServiceAgreements19.29.316.717.927.813.312.322.8-2.6-1.810.2

so:SouthernPower



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value155416152514183137311518251720291618191210112411-11-21-3611-10-14
Percentage of PaymentsPursuantToLongTermServiceAgreements57.772.044.453.646.346.724.754.448.156.434.954.551.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CounterpartyName, us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity

so:PercentageOfConstructionCostsResponsibilityToPay

so:VogtleOwners, so:PlantVogtleUnits3And4, so:CategoryII, so:GeorgiaPower



Period End2020-03-31
Value0.443
Percentage of PercentageOfConstructionCostsResponsibilityToPay100.0

so:VogtleOwners, so:PlantVogtleUnits3And4, so:CategoryIII, so:GeorgiaPower



Period End2020-03-31
Value0.343
Percentage of PercentageOfConstructionCostsResponsibilityToPay77.4

us-gaap:PublicUtility, so:CostCategory, dei:LegalEntity

so:PlantVogtleUnits3And4, so:CategoryII, so:GeorgiaPower



Period End2020-03-31
Value0.557
Percentage of PercentageOfConstructionCostsResponsibilityToPay125.7

so:PlantVogtleUnits3And4, so:CategoryIII, so:GeorgiaPower



Period End2020-03-31
Value0.657
Percentage of PercentageOfConstructionCostsResponsibilityToPay148.3

dei:LegalEntity

so:ProceedsFromFederalFinancingBankLoan

so:GeorgiaPower



Period End2020-03-312019-03-31
Value0835
Percentage of ProceedsFromFederalFinancingBankLoan0.0100.0

us-gaap:PublicUtility, so:VogtleConstructionMonitoringReportNumber, dei:LegalEntity

so:PublicUtilitiesRequestedCapitalConstructionCosts

so:PlantVogtleUnits3And4, so:TwentyFirstVogtleConstructionMonitoringReport, so:GeorgiaPower



Period End2020-02-18
Value6700
Percentage of PublicUtilitiesRequestedCapitalConstructionCosts100.0

so:PlantVogtleUnits3And4, so:TwentySecondVogtleConstructionMonitoringReport, so:GeorgiaPower



Period End2020-02-19
Value674
Percentage of PublicUtilitiesRequestedCapitalConstructionCosts0.0

us-gaap:PublicUtility, us-gaap:SubsequentEventType, dei:LegalEntity

so:PlantVogtleUnits3And4, us-gaap:SubsequentEvent, so:GeorgiaPower