SLG


Line plots across dimensions of each concept
Tables

Table of contents



us-gaap:CommonStockValue
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents
us-gaap:SharesOutstanding
us-gaap:StatementEquityComponents

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax
us-gaap:ProductOrService, us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:Revenues
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:CostsAndExpenses
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:SellingGeneralAndAdministrativeExpense
us-gaap:ConsolidatedEntities

us-gaap:InterestExpense

us-gaap:IncomeTaxExpenseBenefit

us-gaap:ProfitLoss
us-gaap:ConsolidatedEntities

us-gaap:ComprehensiveIncomeNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities

us-gaap:NetIncomeLoss
us-gaap:ConsolidatedEntities

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted
us-gaap:ConsolidatedEntities

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:Assets
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:Liabilities
us-gaap:ConsolidatedEntities

us-gaap:LiabilitiesAndStockholdersEquity
us-gaap:ConsolidatedEntities

us-gaap:StockholdersEquity

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:Land
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongTermDebt

us-gaap:StockholdersEquity

us-gaap:CommonStockValue

us-gaap:RetainedEarningsAccumulatedDeficit
us-gaap:AdjustmentsForNewAccountingPronouncements, slg:CumulativeEffectPeriodOfAdoption

us-gaap:TreasuryStockValue

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInOperatingActivities
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInInvestingActivities
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInFinancingActivities
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInOperatingActivities
us-gaap:ConsolidatedEntities

us-gaap:NetIncomeLoss
us-gaap:ConsolidatedEntities

us-gaap:ProfitLoss
us-gaap:ConsolidatedEntities

us-gaap:DepreciationDepletionAndAmortization
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInInvestingActivities
us-gaap:ConsolidatedEntities

us-gaap:PaymentsToAcquireInvestments
us-gaap:ConsolidatedEntities

us-gaap:NetCashProvidedByUsedInFinancingActivities
us-gaap:ConsolidatedEntities

us-gaap:PaymentsOfDividends
us-gaap:ConsolidatedEntities

us-gaap:PaymentsOfDividends
us-gaap:ConsolidatedEntities

us-gaap:PaymentsForRepurchaseOfCommonStock
us-gaap:ConsolidatedEntities
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
us-gaap:PlanName

us-gaap:OperatingLeaseRightOfUseAsset
us-gaap:ConsolidatedEntities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
us-gaap:ConsolidatedEntities

slg:AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue

slg:ConsolidationOfJointVentureInterest
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

slg:DebtAndEquitySecuritiesCreditLossExpenseReversal

slg:DebtAndPreferredEquityReserves
us-gaap:ConsolidatedEntities
us-gaap:StatementGeographical, us-gaap:CreditFacility
slg:DebtInstrumentNumberofExtensionOptions
us-gaap:StatementGeographical, us-gaap:LongtermDebtType, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:DeferredCompensationPlanAndStockAwardNet
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
slg:DeferredCompensationPlanAndStockAwardShares
us-gaap:StatementEquityComponents

slg:DeferredLoanCostsAndCapitalizedLeaseObligation
us-gaap:ConsolidatedEntities

slg:DistributedEarningsDiluted
us-gaap:ConsolidatedEntities

slg:DistributionToNoncontrollingInterestOperatingPartnership
us-gaap:ConsolidatedEntities
slg:DistributionsPreferredUnits
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

slg:DistributionsToNoncontrollingInterestsOtherPartnerships
us-gaap:ConsolidatedEntities

slg:FinanceLeaseCost

slg:FinancingReceivableAllowanceForCreditLossesWriteOffsAndReclassifications

slg:FinancingReceivablePortfolioSegmentsNumber

slg:IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

slg:IncreaseDecreaseInAccruedLiabilitiesAndOther
us-gaap:ConsolidatedEntities

slg:IncreaseDecreaseInOperatingLeaseLiability
us-gaap:ConsolidatedEntities

slg:IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares
us-gaap:ConsolidatedEntities
slg:IncrementalCommonUnitsAttributabletoSharebasedPaymentArrangements

slg:InterestExpenseNet
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:ConsolidatedEntities
slg:MinorityInterestIncreaseDecreaseFromFairValueAdjustment
us-gaap:ConsolidatedEntities
slg:NetIncomeLossAllocatedToCommonUnitholders

slg:NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic
us-gaap:ConsolidatedEntities

slg:NonCashLeaseExpense
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
slg:NoncontrollingInterestAccruedDividendsOnPreferredUnits
us-gaap:ConsolidatedEntities
slg:NoncontrollingInterestDecreasefromDistributionstoOtherNoncontrollingInterestHolders

slg:OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments
us-gaap:ConsolidatedEntities
slg:OperatingPartnershipNoncontrollingInterestFairValueAdjustment
us-gaap:ConsolidatedEntities
slg:OtherComprehensiveIncomeLossNetofTaxLessPortionAttributabletoNoncontrollingInterest
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

slg:PaymentsForAcquisitionDepositsAndDeferredPurchasePrice
us-gaap:ConsolidatedEntities

slg:PaymentsForProceedsFromOtherInvestments
us-gaap:ConsolidatedEntities

slg:PaymentsForRepurchaseOfPartnershipUnits
us-gaap:ConsolidatedEntities

slg:PaymentsToAcquireLandBuildingsAndImprovements
us-gaap:ConsolidatedEntities

slg:ProceedsFromEquityMethodInvestmentDividendsOrDistributions
us-gaap:ConsolidatedEntities

slg:ProceedsFromNoncontrollingInterestsInOtherPartnerships
us-gaap:ConsolidatedEntities

slg:ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships
us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities
slg:ProfitLossLessPreferredDistributions
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

slg:PurchasePriceFairValueAdjustmentGainLoss
us-gaap:ConsolidatedEntities

slg:PurchasePriceFairValueAdjustmentGross
us-gaap:ConsolidatedEntities

slg:ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

slg:RemovalofFullyDepreciatedRealEstateAssets
us-gaap:ConsolidatedEntities

slg:RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization

slg:RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments
us-gaap:ConsolidatedEntities

slg:ReversalOfAssetsHeldForSale
us-gaap:ConsolidatedEntities

slg:SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease

slg:SellerFinancedPurchases
us-gaap:ConsolidatedEntities
us-gaap:AwardType
slg:ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantsInPeriodFairValue

slg:TotalCostsAndExpensesIncludingNonoperatingIncomeExpense
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

slg:TransactionRelatedCosts
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
slg:WeightedAverageNumberofUnitsOutstandingDiluted

srt:MortgageLoansOnRealEstateInterestRate
us-gaap:MortgageLoansOnRealEstateLoanType

us-gaap:AffiliateCosts
us-gaap:ConsolidatedEntities
us-gaap:AwardType
us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:AwardType, us-gaap:PlanName
us-gaap:PlanName

us-gaap:AmortizationOfAboveAndBelowMarketLeases

us-gaap:AmortizationOfFinancingCosts
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
us-gaap:ConsolidatedEntities

us-gaap:CapitalExpendituresIncurredButNotYetPaid
us-gaap:ConsolidatedEntities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
us-gaap:ConsolidatedEntities

us-gaap:CommonStockDividendsPerShareDeclared
us-gaap:ConsolidatedEntities
us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType, slg:RealEstateByLocation
us-gaap:ConcentrationRiskPercentage1
us-gaap:MajorCustomers, us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType
us-gaap:MajorCustomers, us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType, us-gaap:SubsequentEventType
us-gaap:ConsolidatedEntities, us-gaap:FederalHomeLoanBankAdvancesOption, us-gaap:VariableRate
us-gaap:DebtInstrumentBasisSpreadOnVariableRate1
us-gaap:DebtInstrument, us-gaap:LongtermDebtType, us-gaap:VariableRate
us-gaap:DebtInstrument, us-gaap:SubsequentEventType
us-gaap:Range, us-gaap:DebtInstrument, us-gaap:LongtermDebtType, us-gaap:VariableRate

us-gaap:DepreciationAndAmortization
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:DilutiveSecuritiesEffectOnBasicEarningsPerShareOther
us-gaap:ConsolidatedEntities
us-gaap:DistributedEarnings

us-gaap:DividendsCommonStock
us-gaap:StatementEquityComponents

us-gaap:DividendsPreferredStock
us-gaap:StatementEquityComponents

us-gaap:EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount

us-gaap:EquityMethodInvestmentDividendsOrDistributions
us-gaap:ConsolidatedEntities

us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationRevenue

us-gaap:FinanceLeaseInterestExpense

us-gaap:GainLossOnSaleOfPropertiesNetOfApplicableIncomeTaxes
us-gaap:ConsolidatedEntities

us-gaap:GainsLossesOnSalesOfInvestmentRealEstate
us-gaap:ConsolidatedEntities

us-gaap:IncomeLossFromEquityMethodInvestments
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:IncreaseDecreaseInAccountsReceivable
us-gaap:ConsolidatedEntities

us-gaap:IncreaseDecreaseInDeferredLeasingFees
us-gaap:ConsolidatedEntities

us-gaap:IncreaseDecreaseInDeferredLiabilities
us-gaap:ConsolidatedEntities

us-gaap:IncreaseDecreaseInDueFromRelatedPartiesCurrent
us-gaap:ConsolidatedEntities

us-gaap:IncreaseDecreaseInOtherOperatingAssets
us-gaap:ConsolidatedEntities

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InterestCostsIncurredCapitalized

us-gaap:InterestIncomeExpenseNet

us-gaap:InterestIncomeOperating

us-gaap:InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet
us-gaap:DerivativeInstrumentRisk
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:InvestmentIncomeInterestAndDividend
us-gaap:ConsolidatedEntities
us-gaap:DebtInstrument
us-gaap:LineOfCreditFacilityCommitmentFeePercentage
us-gaap:Range, us-gaap:DebtInstrument

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:MinorityInterestDecreaseFromRedemptions
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:MortgageLoansOnRealEstateAmortizationOfPremium
us-gaap:InvestmentType
us-gaap:MortgageLoansOnRealEstateNewMortgageLoans
us-gaap:ConsolidatedEntities
us-gaap:NetIncomeLossNetOfTaxPerOutstandingLimitedPartnershipUnitDiluted
us-gaap:ConsolidatedEntities
us-gaap:NetIncomeLossPerOutstandingLimitedPartnershipUnitBasicNetOfTax

us-gaap:NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable
us-gaap:ConsolidatedEntities

us-gaap:NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable
us-gaap:ConsolidatedEntities

us-gaap:NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

us-gaap:OperatingLeaseCost
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:OperatingLeaseLeaseIncome
us-gaap:ConsolidatedEntities

us-gaap:OperatingLeaseLeaseIncomeLeasePayments

us-gaap:OperatingLeaseVariableLeaseIncome

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
us-gaap:RelatedPartyTransactionsByRelatedParty, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax
us-gaap:ConsolidatedEntities

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax
us-gaap:DerivativeInstrumentRisk
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:OtherComprehensiveIncomeLossNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
us-gaap:ConsolidatedEntities

us-gaap:OtherIncome
us-gaap:ConsolidatedEntities

us-gaap:OtherNoncashIncomeExpense
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:PartnersCapitalAccountDistributions
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

us-gaap:PartnersCapitalAccountRedemptions
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:PartnersCapitalAccountUnitsSaleOfUnits

us-gaap:PaymentsForRepurchaseOfRedeemablePreferredStock
us-gaap:ConsolidatedEntities

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation
us-gaap:ConsolidatedEntities

us-gaap:PaymentsToAcquireCommercialRealEstate
us-gaap:ConsolidatedEntities

us-gaap:PaymentsToAcquireEquityMethodInvestments
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:Range, us-gaap:StatementClassOfStock
us-gaap:PreferredStockDividendRatePercentage
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
us-gaap:StatementClassOfStock
us-gaap:ConsolidatedEntities
us-gaap:PreferredStockDividendsAndOtherAdjustments
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
us-gaap:PreferredStockDividendsPerShareCashPaid
us-gaap:StatementClassOfStock
us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfSecuredDebt
us-gaap:ConsolidatedEntities

us-gaap:ProceedsFromOtherDebt
us-gaap:ConsolidatedEntities

us-gaap:ProceedsFromPaymentsToMinorityShareholders
us-gaap:ConsolidatedEntities

us-gaap:ProceedsFromRealEstateAndRealEstateJointVentures
us-gaap:ConsolidatedEntities

us-gaap:ProceedsFromStockOptionsExercised
us-gaap:ConsolidatedEntities

us-gaap:ProvisionForLoanAndLeaseLosses
us-gaap:ConsolidatedEntities

us-gaap:ProvisionForLoanLeaseAndOtherLosses
us-gaap:ConsolidatedEntities

us-gaap:RealEstateTaxExpense
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
us-gaap:RelatedPartyTransactionsByRelatedParty, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty

us-gaap:RepaymentsOfOtherDebt
us-gaap:ConsolidatedEntities

us-gaap:RepaymentsOfSecuredDebt
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RevenueFromRelatedParties

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
us-gaap:ConsolidatedEntities
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesConversionOfUnits
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesDividendReinvestmentPlan
us-gaap:StatementEquityComponents
us-gaap:StatementClassOfStock
us-gaap:StockIssuedDuringPeriodSharesNewIssues
us-gaap:AwardType
us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:StockIssuedDuringPeriodValueConversionOfUnits
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueDividendReinvestmentPlan
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:StockRepurchasedDuringPeriodShares
us-gaap:ShareRepurchaseProgram

us-gaap:StraightLineRent
us-gaap:ConsolidatedEntities
us-gaap:Ownership
us-gaap:SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest
us-gaap:Ownership, dei:LegalEntity

us-gaap:TreasuryStockAcquiredAverageCostPerShare
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:TreasuryStockSharesAcquired
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValueAcquiredCostMethod
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities
us-gaap:UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic

us-gaap:UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:WeightedAverageLimitedPartnershipUnitsOutstanding
us-gaap:ConsolidatedEntities
us-gaap:WeightedAverageLimitedPartnershipUnitsOutstandingDiluted

dei:EntityCommonStockSharesOutstanding
us-gaap:ConsolidatedEntities

slg:AccruedInterestPayableAndOther
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

slg:AccumulatedAmortizationOfDeferredCosts

slg:AllowanceForDeferredRentsReceivable
us-gaap:ConsolidatedEntities

slg:BuildingLeaseholdImprovementsGross
us-gaap:ConsolidatedEntities

slg:DiscountOfStructuredFinanceInvestments
us-gaap:ConsolidatedEntities
us-gaap:CounterpartyName, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType
slg:DisposalGroupIncludingDiscontinuedOperationOwnershipPercentageinDisposedAsset

slg:FinancingReceivableRecordedInOtherAssets
slg:CumulativeEffectPeriodOfAdoption

slg:FiniteLivedIntangibleLiabilitiesAccumulatedAmortization

slg:FiniteLivedIntangibleLiabilitiesGross

slg:FiniteLivedIntangibleLiabilitiesNet
us-gaap:ConsolidatedEntities
slg:GeneralAndLimitedPartnersCapitalAccount
us-gaap:ConsolidatedEntities
slg:LimitedPartnershipUnitsHeldByGeneralPartner

slg:LongTermDebtMaturitiesRepaymentsOfPrincipal
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:ConsolidatedEntities
slg:MinorityInterestUnitsOfPartnershipOwnedByNoncontrollingOwners
us-gaap:FairValueByMeasurementBasis
slg:MortgageLoansOnRealEstateFairValueHighEndOfRange
us-gaap:FairValueByMeasurementBasis
slg:MortgageLoansOnRealEstateFairValueLowEndOfRange
us-gaap:MortgageLoansOnRealEstateLoanType
slg:MortgageLoansOnRealEstateLoanValue

slg:MortgageLoansonRealEstateSeniorFinancing
us-gaap:MortgageLoansOnRealEstateLoanType

slg:NetIntangibleAssetsTransferredtoAssetsHeldforSale

slg:NetIntangibleLiabilitiesTransferredtoLiabilitiesRelatedtoAssetsHeldforSale
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, slg:RealEstateByLocation
slg:NumberOfResidentialUnits

slg:NumberofRealEstateBuildings
slg:RealEstateByLocation
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, slg:RealEstateByLocation
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, us-gaap:RealEstateProperties
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, us-gaap:RealEstateProperties, slg:RealEstateByLocation
us-gaap:RealEstateProperties
us-gaap:RealEstateProperties, slg:RealEstateByLocation
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
slg:OperatingPartnershipCommonUnitValuePerShareUseForConversion

slg:OtherComprehensiveIncomeLossDeferredNetLossfromTerminatedHedges

slg:RealEstateWeightedAverageOccupancy
slg:RealEstateByLocation
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty
us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, slg:RealEstateByLocation
us-gaap:RelatedPartyTransactionsByRelatedParty
slg:SecuredDebtAndOtherLoansPayable

slg:SecuredDebtBearingFixedInterestAmount

slg:SecuredDebtBearingVariableInterestAmount

slg:SecuredDebtDeferredFinanceCostsNet

slg:SecuredDebtGross
us-gaap:RelatedPartyTransactionsByRelatedParty
slg:SecuredDebtandOtherLoansPayableNet
us-gaap:LongtermDebtType
slg:SeniorNotesNetofDeferredFinanceCosts
us-gaap:PlanName
slg:ShareBasedCompensationArrangementbyShareBasedPaymentAwardFungibleUnitsPerShare

slg:VariableInterestEntityNotPrimaryBeneficiaryInvestment

us-gaap:AccountsAndNotesReceivableNet
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
us-gaap:ConsolidatedEntities

us-gaap:AdditionalPaidInCapital

us-gaap:AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables
us-gaap:ConsolidatedEntities

us-gaap:AllowanceForLoanAndLeaseLossesRealEstate
us-gaap:ConsolidatedEntities

us-gaap:AreaOfRealEstateProperty

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation
us-gaap:ConsolidatedEntities

us-gaap:AvailableForSaleSecuritiesDebtSecurities
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument
us-gaap:FairValueByMeasurementBasis
us-gaap:FinancialInstrument
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisitionPercentageOfVotingInterestsAcquired
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets

us-gaap:CollateralAlreadyPostedAggregateFairValue

us-gaap:ContractWithCustomerLiability
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentCarryingAmount
us-gaap:LongtermDebtType
us-gaap:DebtInstrument, us-gaap:SubsequentEventType
us-gaap:DebtInstrumentFaceAmount

us-gaap:DeferredCostsCurrentAndNoncurrent
us-gaap:ConsolidatedEntities

us-gaap:DeferredCostsLeasingGross
us-gaap:LongtermDebtType
us-gaap:DeferredFinanceCostsNet
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:DeferredRentReceivablesNet
us-gaap:ConsolidatedEntities

us-gaap:DerivativeFairValueOfDerivativeAsset
us-gaap:DerivativeInstrumentRisk
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:BalanceSheetLocation
us-gaap:DerivativeFairValueOfDerivativeLiability
us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DebtInstrument, us-gaap:DerivativeInstrumentRisk, us-gaap:SubsequentEventType
us-gaap:DerivativeFixedInterestRate
us-gaap:DerivativeInstrumentRisk
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupIncludingDiscontinuedOperationConsideration
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType

us-gaap:DividendsPayableCurrentAndNoncurrent
us-gaap:ConsolidatedEntities

us-gaap:DueFromJointVentures

us-gaap:DueFromOtherRelatedParties

us-gaap:DueFromRelatedParties
us-gaap:ConsolidatedEntities
us-gaap:AwardType
us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationAssets
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationEquity
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:EquityMethodInvestmentSummarizedFinancialInformationLiabilitiesAndEquity

us-gaap:EquityMethodInvestments
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:FinanceLeaseLiability
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:FinanceLeaseRightOfUseAsset
us-gaap:ConsolidatedEntities
us-gaap:MortgageLoansOnRealEstateLoanType
us-gaap:FinancingReceivableAllowanceForCreditLosses

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

us-gaap:FiniteLivedIntangibleAssetsGross
us-gaap:ConsolidatedEntities
us-gaap:GeneralPartnersCapitalAccountUnitsOutstanding

us-gaap:InvestmentBuildingAndBuildingImprovements
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:MortgageLoansOnRealEstateLoanType, us-gaap:Range, us-gaap:InvestmentType
us-gaap:InvestmentInterestRate
us-gaap:InvestmentType
us-gaap:InvestmentOwnedUnderlyingFaceAmountAtMarketValue
us-gaap:MortgageLoansOnRealEstateLoanType, us-gaap:InvestmentType

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:LimitedPartnersCapitalAccount
us-gaap:ConsolidatedEntities
us-gaap:LimitedPartnersCapitalAccountUnitsOutstanding

us-gaap:LineOfCredit
us-gaap:ConsolidatedEntities
us-gaap:DebtInstrument
us-gaap:DebtInstrument
us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity
us-gaap:StatementGeographical, us-gaap:CreditFacility
us-gaap:MortgageLoansOnRealEstateLoanType, us-gaap:Range, us-gaap:InvestmentType, us-gaap:VariableRate
us-gaap:LoansReceivableBasisSpreadOnVariableRate
us-gaap:FairValueByMeasurementBasis
us-gaap:LongTermDebtFairValue

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear
us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:LongtermDebtPercentageBearingFixedInterestAmount
us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis
us-gaap:LongtermDebtPercentageBearingVariableInterestAmount
us-gaap:FairValueByMeasurementBasis

us-gaap:MarketableSecurities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:MinorityInterestInOperatingPartnerships
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
us-gaap:MinorityInterestInPreferredUnitHolders
us-gaap:ConsolidatedEntities, us-gaap:Ownership
us-gaap:MinorityInterestOwnershipPercentageByNoncontrollingOwners

us-gaap:MortgageLoansOnRealEstate

us-gaap:MortgageLoansOnRealEstateCommercialAndConsumerNet
us-gaap:MortgageLoansOnRealEstateLoanType
us-gaap:NotesReceivableNet

us-gaap:OperatingLeaseLiability
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:OtherAssets
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:OtherLiabilities
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:OtherMinorityInterests
us-gaap:ConsolidatedEntities
us-gaap:PartnersCapital
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:PartnersCapitalAccountUnits
us-gaap:ConsolidatedEntities
us-gaap:PartnersCapitalAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities
us-gaap:PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents
us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock
us-gaap:PreferredUnitsAuthorized

us-gaap:RealEstateInvestmentPropertyAccumulatedDepreciation
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:RealEstateInvestmentPropertyAtCost
us-gaap:ConsolidatedEntities

us-gaap:RealEstateInvestmentPropertyNet
us-gaap:ConsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:RedeemableNoncontrollingInterestEquityCommonCarryingAmount

us-gaap:RedeemableNoncontrollingInterestEquityPreferredCarryingAmount
us-gaap:ConsolidatedEntities

us-gaap:RestrictedCashAndCashEquivalents
us-gaap:ConsolidatedEntities

us-gaap:SecuredDebt
slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities
us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:SecurityDepositLiability
us-gaap:ConsolidatedEntities

us-gaap:SeniorNotes
us-gaap:ConsolidatedEntities
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
us-gaap:PlanName
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:RelatedPartyTransactionsByRelatedParty, us-gaap:StatementEquityComponents
us-gaap:StatementClassOfStock, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockShares

us-gaap:UnsecuredDebt
us-gaap:ConsolidatedEntities

Tables

  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CommonStockValue ▁▁▁▁▁▁▁▁▁▁▁▁██████████▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁00000000000011111111110000000000000000NANANA
 us-gaap:SharesOutstanding us-gaap:ConsolidatedEntities,us-gaap:StatementEquityComponents srt:Subsidiaries,us-gaap:CommonStock▁▄▆▇██767981828383NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:SharesOutstanding us-gaap:StatementEquityComponents us-gaap:CommonStock▁▂▂▃▃▃▄▄▅▆▇▇█████████▇▇▇▇▆▆▅▅▅▅▅▄▄▄767981828383858589929798100100100100100999999999795959594929191919089888585NANA78NANANA
us-gaap:CommonStockSharesIssued ▁▂▂▃▃▃▃▃▄▅▇▇▇▇▇▇▇▇███▇▇▇▇▇▆▆▆▆▅▅▅▄▄▄▃▂77808283848486869093989910110110010010010010310310310099999898959595949393928989878481NANANA
us-gaap:CommonStockSharesOutstanding ▁▂▂▃▃▃▃▃▄▅▇▇▇▇▇▇▇▇███▇▇▇▇▇▆▆▆▆▅▅▅▄778082838484868690939899101101100100100100103103103100999998989595959493939289NA878481NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding 82NA868787NA909295NA102104105NA105104104NA10399103NA999998NA959494NA939390NA888681NA797979
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic 77NA828283NA858790NA9799100NA100100100NA999998NA959595NA919191NA908986NA858379NA787877
us-gaap:EarningsPerShareBasic ▃▂▂▄▂▁▃▃▃▂▂▂▂▂▂▃▂▃▃▁▂▂▂▄▃▂▂▂▂▂▂▃▂▂▂█▃▂▃▃▂1.470.210.41.940.52-0.731.031.191.120.290.40.080.110.440.341.330.231.021.64-0.390.440.590.682.471.540.390.40.090.210.230.091.150.290.030.086.31.020.091.431.760.19
us-gaap:EarningsPerShareDiluted ▃▂▂▄▂▁▃▃▃▂▂▂▂▂▂▃▂▃▃▁▂▂▂▄▃▂▂▂▂▂▂▃▂▂▂█▃▂▃▃▂1.470.210.41.940.52-0.731.031.191.120.290.40.080.110.440.341.330.231.02000000000000021.64-0.390.440.590.682.461.530.390.40.090.210.230.091.140.290.030.086.261.010.091.421.750.19
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax ▂▂▂▂▂▂▂▂▂▃▃▄▃▃▄█▅▄▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▂▂▂▃▁▂▁▁314308313313304317307301301361374398377374416617455425432409396386390387381374363365369350361349339328308300334262319251250
us-gaap:Revenues ▂▂▂▂▂▂▂▂▂▃▃▄▃▃▄█▅▄▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▂▂▂▃▁▂▁▁314308313313304317307301301361374398377374416617455425432409396386390387381374363365369350361349339328308300334262319251250
 us-gaap:Revenues us-gaap:ConsolidatedEntities srt:Subsidiaries▂▂▂▂▁▂▁▁▁▅▆█▆314308313313304317307301301361374398377NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,slg:RealEstateSegment▂▁▁▁▁▁▁▁▁▂▃▃▃▃▃█▄▄▄▃▃▃▃▃275265262261254259258251256316326337330329335569400380382363354345346340NANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,slg:StructuredFinanceSegment▁▂▃▃▃▄▃▃▂▂▂▅▂▂█▂▄▂▃▂▂▁▂▁384251515057484945454760464481475444494542414339NANANANANANANANANANANANANANANANANA
us-gaap:CostsAndExpenses 53NA595857NA565659NA757074787975797678707671727073NA776973NA836873NA696260NA585256
 us-gaap:CostsAndExpenses us-gaap:ConsolidatedEntities srt:Subsidiaries53NA595857NA565659NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostsAndExpenses us-gaap:RelatedPartyTransactionsByRelatedParty us-gaap:CorporateJointVenture▅▅▅▄▆▆▇▅█▂▁▁▁51495048545356505941383938NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:SellingGeneralAndAdministrativeExpense ▁▆▄▆▆▆▂▃▄█▄▅▅▆▆▅▅▃▄▄▆▃▃▄▄19252325252620222328232424252524242223232522222323NA202121NA202020NA182220NA181818
 us-gaap:SellingGeneralAndAdministrativeExpense us-gaap:ConsolidatedEntities srt:Subsidiaries▁▇▅▇▇█▂▄▅192523252526202223NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:InterestExpense 56NA63606028646154397271727178951028884767681837980NA838381NA868280NA756964NA5657NA
us-gaap:IncomeTaxExpenseBenefit ▄▄▄▁▁▁▁▄▁▄▁█111000010102NA000101101122NA221NA000NANANANANANANANA
us-gaap:ProfitLoss ▅▃▃▆▄▁▅▅▅▃▃▃▂▄▃▆▃▅▆▂▄▄▄█▆127244017352-58991151133845160534314932114176-29556573250156NA453130NA2811835NA1654993NA12415026
 us-gaap:ProfitLoss us-gaap:ConsolidatedEntities srt:Subsidiaries▇▃▄█▄▁▆▆▆127244017352-5899115113NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTax ▄▃▃▆▃▁▅▅▅▃▄▃▃▄▄▆▃▅▆▂▄▄▄█▆66322514028-7895111115364299834013718112162-34425671247150NA403429NA1410637NA1152598NANANANA
 us-gaap:ComprehensiveIncomeNetOfTax us-gaap:ConsolidatedEntities srt:Subsidiaries▆▄▄█▄▁▇▇▇75362915133-79103119123NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▄▃▃▆▃▁▅▅▅▄▄▃▃▅▄▆▃▅▆▂▄▄▄█▆71362814832-80103120124424513-4914514923121171-28506177259156NA443933NA2711439NA13540103NANANANA
 us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest us-gaap:ConsolidatedEntities srt:Subsidiaries▆▅▄█▄▁▇▇▇71362814832-80103120124NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▃▂▂▄▂▁▃▃▃▂▂▂▂▂▂▃▂▃▄▁▂▂▂▅▃▂▂▂▂▂▂▃▂▂▂█▃▂▃▃▂118213616447-579110710531421115473713726105167-35476068239149404027262725110331014534881411914422
 us-gaap:NetIncomeLoss us-gaap:ConsolidatedEntities srt:Subsidiaries▇▃▄█▄▁▆▆▆▄▄▃▃124223817349-609611211033441215NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic ▃▂▂▄▂▁▃▃▃▂▂▂▂▂▂▃▂▃▄▁▂▂▂▅▃▂▂▂▂▂▂▃▂▂▂█▃▂▃▃▂114173316143-61881031012738811443413323101163-394356642351463737818197103252752680711113715
us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted ▅▃▃▆▄▁▅▅▅▃▃▃▃▃▃▆▃▅▆▂▃▄▄█▆▃▃▃▃121183416946-64931091072940811453513924105170-394559672441503838819NA810626NA753882NA113139NA
 us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted us-gaap:ConsolidatedEntities srt:Subsidiaries121NA3416946NA93109107NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▇▆▆▇▆▅▇▇▇▇▆▆▁▇▆█▆▇▇▇▇▆▆█▇833850788634-1465115996845116NA434NA272NA1NANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets ▃▂▃▃▃▂▃▃▃▃▄▄▅▅▅▆███▆▆▆▆▅▄▄▄▄▄▄▃▃▃▃▃▂▁▁1322012766132941362913385127511345513713133801398215109153091587715857157901754419585198571949017266170801709617237167171536314959145741440114543143871428414139137611348313162126441144211300NANANA
 us-gaap:Assets us-gaap:ConsolidatedEntities srt:Subsidiaries▅▁▅█▆▁132201276613294136291338512751NANANA13982NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Assets us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments us-gaap:OperatingSegments,slg:RealEstateSegment▂▂▂▂▁▁▂▂▂▂▃▃▄▄▄▆███▆1134511063112161130810943104811125611249111441169612939131611391213868139921586518195181751796615562NA15671NANANANANANANANANANANANANANANANANANANA
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us-gaap:Liabilities ▃▂▂▃▂▂▂▂▁▂▃▃▃▃▃▅███▅▅▅▆▅▄▃▃▃▃▃▃▃▂▂▂▂▁▁72516555684370626843611564186683606566297153717273807330727590081117911431111129186892790969419901678977627750873857368721871106998682268336635622456825818NANANA
 us-gaap:Liabilities us-gaap:ConsolidatedEntities srt:Subsidiaries█▄▅▇▅▁725165556843706268436115NANANA6629NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LiabilitiesAndStockholdersEquity ▃▂▃▃▃▂▃▃▃▃▄▄▅▅▅▆███▆▆▆▆▅▄▄▄▄▄▄▃▃▃▃▃▂▁▁1322012766132941362913385127511345513713133801398215109153091587715857157901754419585198571949017266170801709617237167171536314959145741440114543143871428414139137611348313162126441144211300NANANA
 us-gaap:LiabilitiesAndStockholdersEquity us-gaap:ConsolidatedEntities srt:Subsidiaries▅▁▅█▆▁132201276613294136291338512751NANANA13982NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:StockholdersEquity ▂▃▃▄▄▄▅▅▆▅▇▇███████▇▇▇▇▆▆▆▅▅▅▅▅▅▅▄▄▄▂▁52635441569258095797590162146190648762256817693572637324729373187268728772387115714869376844678066256525628162346417641963716321616259756028586950954879NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CashAndCashEquivalentsAtCarryingValue █▂▁▁▁▁▂▄▄▁▃▃▇▄▆▄▄▃▃▃▄▄▃▄▆▂▂▂▃▂▂▃▁▁▅▅▃▄▃▅▂554166121148144129160287288127241270468279405276316255244215330281253308447206209198220189162256133138394390234332270339167
 us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:ConsolidatedEntities srt:Subsidiaries█▂▁▁▁▁▂▄▄▁554166121148144129160287288127NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
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us-gaap:Land ▁▁▁▂▁▁▁▂▂▃▄▄▅▅▅▆▇██▆▆▆▆▅▄▄▄▄▄▄▄▄▄▃▃▃▂▁16621751186019291775177418271893209823572917293632953309334741084115477946893756383038443833346631123032286828662886288629372872281626842581247219741750NANANA
 us-gaap:Land slg:InvestmentsByConsolidatedAndNonconsolidatedEntities us-gaap:VariableInterestEntityPrimaryBeneficiary▁█199205NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Land us-gaap:ConsolidatedEntities srt:Subsidiaries▁▃▆█▄▄166217511860192917751774NANANA2357NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Land us-gaap:ConsolidatedEntities,slg:InvestmentsByConsolidatedAndNonconsolidatedEntities srt:Subsidiaries,us-gaap:VariableInterestEntityPrimaryBeneficiary▁█199205NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:FiniteLivedIntangibleAssetsNet ▁▁▁▁▁▁▁▁▁▁▂▂▃▄▃██▇▇▇▇▄▄▅▆▆▆▆▆▆▇▇▇▆▇▆222630352225212341487685232240227602615535546541559281303319414403406435445462492500507480512409NA624NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType slg:CreditFacility2012,us-gaap:LineOfCredit█▂▃▅▅▄▂▃▁▁▃▂▁▁▁▃▅▆1300200328663782492136351-930275195-5-6-6277766985NANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:DebtInstrument,us-gaap:LongtermDebtType slg:TermLoan,us-gaap:LineOfCredit██████████▄▄▄▄▄▁▁▁150015001500150015001500150015001500150012001200120012001200930929929NANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquity ▂▃▃▄▄▄▅▅▆▅▇▇███████▇▇▇▇▆▆▆▅▅▅▅▅▅▅▄▄▄▂▁52635441569258095797590162146190648762256817693572637324729373187268728772387115714869376844678066256525628162346417641963716321616259756028586950954879NANANA
us-gaap:CommonStockValue ▁▁▁▁▁▁▁▁▁▁▁▁██████████▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁00000000000011111111110000000000000000NANANA
us-gaap:RetainedEarningsAccumulatedDeficit ▁▁▂▃▂▃▅▅▆▂▄▄▅▆▆▆▆▆█▇▇▇██▇▆▆▆▇▇▇▇▇▇█▇▂▂10991084122512881210127814761457158311391410143114961578161216551620164317721657169017521813179716881619163616311665170117281741166517041763172112071172NANANA
us-gaap:TreasuryStockValue ▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▁▁▁███████████████▇▇▇▇▇124124124124124124124124124124124124124124124101010335325325320320320320317316316322322319319319308307307306303NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▁▄▃▄▆▇███▇▇▇▇▇▅▅▅▅▅▅▅▅▆▅▅▅▅▅▄▄▄▄▄▄▄▅▅▄-80-28-40-28-4153632281814141622-14-16-17-8-15-10-11-6-2-6-14-15-19-18-26-29-29-28-24-28-24-21-13-22NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▁▂▂▅▂▄▂▅▃▄▃▆▃▄▄█▃▆▃▄▃▃▃▆▂427781155621237115194131102197116125135259114203891429011310018888NANANA102NANANA56NANANA79NANANA66
 us-gaap:NetCashProvidedByUsedInOperatingActivities us-gaap:ConsolidatedEntities srt:Subsidiaries▁▃▃█▂▆▃█▄427781155621237115194NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetCashProvidedByUsedInInvestingActivities ▄▅▅▄▄▅▅▄▅▅▅▄▄▄▅█▅▄▁▃▅▄▃▄▄-129355225-174-291181232-18745682162-29329-2822781787338-279-1728-48823028-507-246-71NANANA-174NANANA-294NANANA30NANANA-60
us-gaap:NetCashProvidedByUsedInFinancingActivities ▆▄▄▅▅▄▄▅▄▄▄▅▅▅▄▁▄▅█▅▄▅▆▅▅466-407-331-35246-284-42437-422-327-295-1014230-284-2087-392871667230-271-113351-81224NANANA102NANANA232NANANA-209NANANA-182
 us-gaap:NetCashProvidedByUsedInFinancingActivities us-gaap:ConsolidatedEntities srt:Subsidiaries█▁▂▄▆▂▁▅▁466-407-331-35246-284-42437-422NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▁▂▂▅▂▄▂▅▃▄▃▆▃▄▄█▃▆▃▄▃▃▃▆▂427781155621237115194131102197116125135259114203891429011310018888NANANA102NANANA56NANANA79NANANA66
 us-gaap:NetCashProvidedByUsedInOperatingActivities us-gaap:ConsolidatedEntities srt:Subsidiaries▁▃▃█▂▆▃█▄427781155621237115194NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▃▂▂▄▂▁▃▃▃▂▂▂▂▂▂▃▂▃▄▁▂▂▂▅▃▂▂▂▂▂▂▃▂▂▂█▃▂▃▃▂118213616447-579110710531421115473713726105167-35476068239149404027262725110331014534881411914422
 us-gaap:NetIncomeLoss us-gaap:ConsolidatedEntities srt:Subsidiaries▇▃▄█▄▁▆▆▆▄▄▃▃124223817349-609611211033441215NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▅▃▃▆▄▁▅▅▅▃▃▃▂▄▃▆▃▅▆▂▄▄▄█▆127244017352-58991151133845160534314932114176-29556573250156NA453130NA2811835NA1654993NA12415026
 us-gaap:ProfitLoss us-gaap:ConsolidatedEntities srt:Subsidiaries▇▃▄█▄▁▆▆▆127244017352-5899115113NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DepreciationDepletionAndAmortization ▁▁▁▁▁▁▁▁▁▁▂▂▂▂▂█▃▂▃▄▂▂▂▂▁70677372717473717288951369810811743218711415320511410410110093NANANA85NANANA80NANANA63NANA5555
 us-gaap:DepreciationDepletionAndAmortization us-gaap:ConsolidatedEntities srt:Subsidiaries▄▁▇▆▅█▇▅▆706773727174737172NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▄▅▅▄▄▅▅▄▅▅▅▄▄▄▅█▅▄▁▃▅▄▃▄▄-129355225-174-291181232-18745682162-29329-2822781787338-279-1728-48823028-507-246-71NANANA-174NANANA-294NANANA30NANANA-60
us-gaap:PaymentsToAcquireInvestments 223NA3293430NA48374229NA814524024223271101172957421217419616410615016111582195NANANANANANANANANANANANA
 us-gaap:PaymentsToAcquireInvestments us-gaap:ConsolidatedEntities srt:Subsidiaries223NA3293430NA48374229NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▆▄▄▅▅▄▄▅▄▄▄▅▅▅▄▁▄▅█▅▄▅▆▅▅466-407-331-35246-284-42437-422-327-295-1014230-284-2087-392871667230-271-113351-81224NANANA102NANANA232NANANA-209NANANA-182
 us-gaap:NetCashProvidedByUsedInFinancingActivities us-gaap:ConsolidatedEntities srt:Subsidiaries█▁▂▄▆▂▁▅▁466-407-331-35246-284-42437-422NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PaymentsOfDividends ▇▆▆▇▇▆▆▇▇▇███▇▇▇▇▄▄▄▃▁▁▁▁79757677777676788181838484797878786564646252515151NANANA38NANANA28NANANA15NANANA12
 us-gaap:PaymentsOfDividends us-gaap:ConsolidatedEntities srt:Subsidiaries▂▁▁▂▃▁▂▄█807979808179808285NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PaymentsOfDividends ▇▆▆▇▇▆▆▇▇▇███▇▇▇▇▄▄▄▃▁▁▁▁79757677777676788181838484797878786564646252515151NANANA38NANANA28NANANA15NANANA12
 us-gaap:PaymentsOfDividends us-gaap:ConsolidatedEntities srt:Subsidiaries▂▁▁▂▃▁▂▄█807979808179808285NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PaymentsForRepurchaseOfCommonStock ▄▄▂▂▂▄▂▆▇█▃▄▁▁▁▁▁2192096575342193534238245613821100000NANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PaymentsForRepurchaseOfCommonStock us-gaap:ConsolidatedEntities srt:Subsidiaries▅▅▂▂▁▅▁▇█21920965753421935342382NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31

Common Stock Value

us-gaap:CommonStockValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value000000000000111111111100000000000000000
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Par Or Stated Value Per Share

Shares Outstanding

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

us-gaap:SharesOutstanding

srt:Subsidiaries, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value767981828383
Percentage of SharesOutstanding100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-312009-12-312008-12-31
Value767981828383858589929798100100100100100999999999795959594929191919089888585787757
Percentage of SharesOutstanding100.0100.0100.0100.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Shares Issued

Common Stock Shares Issued

us-gaap:CommonStockSharesIssued



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value7780828384848686909398991011011001001001001031031031009999989895959594939392898987848180
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value77808283848486869093989910110110010010010010310310310099999898959595949393928987848180
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Authorized

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value8286878790929510210410510510410410399103999998959494939390888681797979
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value778282838587909799100100100100999998959595919191908986858379787877
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.470.210.41.940.52-0.731.031.191.120.290.40.080.110.440.341.330.231.021.64-0.390.440.590.682.471.540.390.40.090.210.230.091.150.290.030.086.31.020.091.431.760.19
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.470.210.41.940.52-0.731.031.191.120.290.40.080.110.440.341.330.231.02000000000000021.64-0.390.440.590.682.461.530.390.40.090.210.230.091.140.290.030.086.261.010.091.421.750.19
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Income Loss From Continuing Operations Per Basic Share

Income Loss From Continuing Operations Per Diluted Share

Revenue From Contract With Customer Including Assessed Tax

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value314308313313304317307301301361374398377374416617455425432409396386390387381374363365369350361349339328308300334262319251250
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductOrService, us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:ManagementServiceBase, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value242324233
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.71.40.81.20.81.50.81.01.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.71.40.81.20.81.50.81.01.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ManagementServiceBase us-gaap:CorporateJointVenture100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value314308313313304317307301301361374398377374416617455425432409396386390387381374363365369350361349339328308300334262319251250
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value314308313313304317307301301361374398377
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, slg:RealEstateSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value275265262261254259258251256316326337330329335569400380382363354345346340
Percentage of Revenues87.786.283.683.583.681.784.183.685.087.587.284.887.788.180.692.388.089.588.689.089.489.488.788.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax87.786.283.683.583.681.784.183.685.087.587.284.887.788.180.692.388.089.588.689.089.489.488.788.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments slg:RealEstateSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, slg:StructuredFinanceSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value384251515057484945454760464481475444494542414339
Percentage of Revenues12.313.816.416.516.418.315.916.415.012.512.815.212.311.919.47.712.010.511.411.010.610.611.310.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax12.313.816.416.516.418.315.916.415.012.512.815.212.311.919.47.712.010.511.411.010.610.611.310.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:OperatingSegments slg:StructuredFinanceSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Operating Costs And Expenses

Costs And Expenses

us-gaap:CostsAndExpenses



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value53595857565659757074787975797678707671727073776973836873696260585256
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.119.118.619.018.518.719.820.317.819.721.019.112.217.517.918.217.119.418.418.518.319.321.219.019.923.219.721.622.420.818.018.221.022.6

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value53595857565659
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax17.119.118.619.018.518.719.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value51495048545356505941383938
Percentage of CostsAndExpenses95.80.084.883.293.80.099.089.5100.00.050.155.352.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax16.416.116.215.517.816.718.316.719.811.510.29.810.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:CorporateJointVenture0.00.00.00.00.00.00.00.00.00.00.00.00.0

Selling General And Administrative Expense

us-gaap:SellingGeneralAndAdministrativeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value19252325252620222328232424252524242223232522222323202121202020182220181818
Percentage of SellingGeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.28.37.68.18.58.26.77.57.87.86.46.16.46.96.14.05.35.45.45.76.45.95.86.26.15.75.95.75.75.96.06.17.56.05.87.37.3

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value192523252526202223
Percentage of SellingGeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.28.37.68.18.58.26.77.57.8
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Interest Expense

us-gaap:InterestExpense



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value56636060286461543972717271789510288847676818379808383818682807569645657
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax18.120.319.420.08.920.820.418.211.019.418.119.219.118.915.522.420.919.718.719.321.121.320.421.223.022.922.123.923.723.724.623.119.417.822.8

Other Nonoperating Income Expense

Income Loss From Continuing Operations

Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-31
Value111000010102000101101122221000
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.30.30.30.20.30.30.10.40.20.40.00.60.20.20.00.30.10.30.30.10.30.40.50.80.60.60.40.00.00.0

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value127244017352-58991151133845160534314932114176-295565732501564531302811835165499312415026
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax40.47.913.055.517.3-18.432.338.537.710.612.24.00.214.410.424.17.126.940.9-7.114.016.918.964.641.112.58.68.27.933.910.45.3182.728.139.059.810.4

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value127244017352-5899115113
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax40.47.913.055.517.3-18.432.338.537.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value66322514028-7895111115364299834013718112162-3442567124715040342914106371152598
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax21.010.78.044.99.3-24.831.137.038.310.011.32.52.522.49.722.34.126.437.6-8.410.614.618.464.039.411.09.68.14.130.511.03.8174.829.3

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value75362915133-79103119123
Percentage of ComprehensiveIncomeNetOfTax113.4111.3117.7107.9117.6100.8108.0107.6107.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax23.911.99.448.411.0-25.033.639.841.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value71362814832-80103120124424513-4914514923121171-28506177259156443933271143913540103
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax22.911.89.047.310.7-25.433.639.941.211.912.23.5-1.324.511.024.25.228.639.7-6.912.815.819.767.041.212.310.79.27.732.711.54.4179.731.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value71362814832-80103120124
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax22.911.89.047.310.7-25.433.639.941.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Net Income Loss

us-gaap:NetIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value118213616447-579110710531421115473713726105167-35476068239149404027262725110331014534881411914422
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax37.76.911.852.715.6-18.129.935.635.08.811.43.04.012.89.122.25.924.738.7-8.611.915.717.561.839.310.911.27.57.17.87.131.79.83.14.7177.626.55.637.357.58.8

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value124223817349-609611211033441215
Percentage of NetIncomeLoss105.2104.7104.7105.0104.8106.0105.2105.2105.0104.1104.3103.5103.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax39.77.212.355.316.4-19.231.537.536.79.111.93.14.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss Available To Common Stockholders Basic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value114173316143-61881031012738811443413323101163-394356642351463737818197103252752680711113715
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax36.55.710.651.514.4-19.328.734.433.77.710.42.13.011.88.221.65.123.837.9-9.610.914.716.660.838.39.910.22.35.15.72.129.57.40.92.3175.124.22.734.954.56.0

Net Income Loss Available To Common Stockholders Diluted

us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value121183416946-64931091072940811453513924105170-394559672441503838819810626753882113139
Percentage of NetIncomeLossAvailableToCommonStockholdersDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax38.56.011.154.115.1-20.430.236.235.58.110.92.23.112.38.622.55.324.739.4-9.611.415.317.363.139.610.210.52.35.32.330.57.72.3179.124.735.555.5

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value121341694693109107
Percentage of NetIncomeLossAvailableToCommonStockholdersDiluted100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax38.511.154.115.130.236.235.5
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-30
Value833850788634-14651159968451164342721
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.71.01.22.81.7-0.32.42.92.81.80.91.0-3.81.71.31.91.22.22.21.52.21.21.32.91.81.31.01.10.82.30.70.6

Assets

us-gaap:Assets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value132201276613294136291338512751134551371313380139821510915309158771585715790175441958519857194901726617080170961723716717153631495914574144011454314387142841413913761134831316212644114421130010487
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value13220127661329413629133851275113982
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets srt:Subsidiaries100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, slg:RealEstateSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value113451106311216113081094310481112561124911144116961293913161139121386813992158651819518175179661556215671
Percentage of Assets85.886.784.483.081.882.283.782.083.383.685.686.087.687.588.690.492.991.592.290.191.7
Percentage of Assets85.886.784.483.081.882.283.782.083.383.685.686.087.687.588.690.492.991.592.290.191.7
Percentage of Assets us-gaap:OperatingSegments slg:RealEstateSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, slg:StructuredFinanceSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value187517032078232124422269219824632236228621702148196519891798167813901682152317041424
Percentage of Assets14.213.315.617.018.217.816.318.016.716.414.414.012.412.511.49.67.18.57.89.98.3
Percentage of Assets14.213.315.617.018.217.816.318.016.716.414.414.012.412.511.49.67.18.57.89.98.3
Percentage of Assets us-gaap:OperatingSegments slg:StructuredFinanceSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value725165556843706268436115641866836065662971537172738073307275900811179114311111291868927909694199016789776277508738573687218711069986822683366356224568258185489
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets54.951.451.551.851.148.047.748.745.347.447.346.846.546.246.151.357.157.657.053.252.353.254.653.951.451.051.551.350.750.249.849.549.650.750.449.249.751.552.3

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value7251655568437062684361156629
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets54.951.451.551.851.148.047.4
Percentage of Assets srt:Subsidiaries54.951.451.551.851.148.047.4

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value132201276613294136291338512751134551371313380139821510915309158771585715790175441958519857194901726617080170961723716717153631495914574144011454314387142841413913761134831316212644114421130010487
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value13220127661329413629133851275113982
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets srt:Subsidiaries100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value526354415692580957975901621461906487622568176935726373247293731872687287723871157148693768446780662565256281623464176419637163216162597560285869509548794388
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets39.842.642.842.643.346.346.245.148.544.545.145.345.746.246.241.737.136.737.141.241.940.639.740.643.143.643.143.344.144.644.644.744.844.345.846.444.543.241.8

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value55416612114814412916028728812724127046827940527631625524421533028125330844720620919822018916225613313839439023433227033916734372645
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.21.30.91.11.11.01.22.12.20.91.61.82.91.82.61.61.61.31.31.31.91.61.51.82.91.41.41.41.51.31.11.81.01.03.03.12.02.90.00.00.03.30.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value554166121148144129160287288127
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.21.30.91.11.11.01.22.12.20.9
Percentage of Assets srt:Subsidiaries4.21.30.91.11.11.00.00.00.00.9

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value329336299319370381350434452494328
Percentage of CashAndCashEquivalentsAtCarryingValue59.4202.4246.2214.4256.9294.5218.9151.2156.7387.0117.5
Percentage of Assets2.52.62.32.32.83.02.63.23.43.52.1
Percentage of Assets us-gaap:CorporateJointVenture0.00.00.00.00.00.00.00.00.00.00.0

Land

us-gaap:Land



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value166217511860192917751774182718932098235729172936329533093347410841154779468937563830384438333466311230322868286628862886293728722816268425812472197417501379
Percentage of Land100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets12.613.714.014.213.313.913.613.815.716.919.319.220.820.921.223.421.024.124.121.822.422.522.220.720.320.319.719.919.820.120.620.320.519.919.619.617.315.513.1

slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value199205
Percentage of Land12.011.7
Percentage of Assets1.51.6
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1662175118601929177517742357
Percentage of Land100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets12.613.714.014.213.313.916.9
Percentage of Assets srt:Subsidiaries12.613.714.014.213.313.916.9

us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

srt:Subsidiaries, us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value199205
Percentage of Land12.011.7
Percentage of Assets1.51.6
Percentage of Assets srt:Subsidiaries us-gaap:VariableInterestEntityPrimaryBeneficiary0.00.0

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet



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
Value222630352225212341487685232240227602615535546541559281303319414403406435445462492500507480512409624
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.30.20.20.20.20.30.30.50.61.51.51.43.43.12.72.83.13.31.61.81.92.72.72.83.03.13.23.43.53.73.63.93.25.5

Long Term Debt

us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:LongTermDebt

slg:CreditFacility2012, us-gaap:LineOfCredit



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
Value1300200328663782492136351-930275195-5-6-6277766985
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets9.81.62.54.95.83.91.02.6-0.10.21.81.3-0.0-0.0-0.01.63.95.0
Percentage of Assets slg:CreditFacility2012 us-gaap:LineOfCredit0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

slg:TermLoan, us-gaap:LineOfCredit



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
Value150015001500150015001500150015001500150012001200120012001200930929929
Percentage of LongTermDebt115.4750.0456.6226.2191.6304.81097.3427.0-16304.34950.5435.1615.1-21428.6-19047.6-17391.3335.3121.394.4
Percentage of Assets11.311.711.311.011.211.811.110.911.210.77.97.87.67.67.65.34.74.7
Percentage of Assets slg:TermLoan us-gaap:LineOfCredit0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity

us-gaap:StockholdersEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value526354415692580957975901621461906487622568176935726373247293731872687287723871157148693768446780662565256281623464176419637163216162597560285869509548794388
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets39.842.642.842.643.346.346.245.148.544.545.145.345.746.246.241.737.136.737.141.241.940.639.740.643.143.643.143.344.144.644.644.744.844.345.846.444.543.241.8

Common Stock Value

us-gaap:CommonStockValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value000000000000111111111100000000000000000
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value10991084122512881210127814761457158311391410143114961578161216551620164317721657169017521813179716881619163616311665170117281741166517041763172112071172949
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.38.59.29.59.010.011.010.611.88.19.39.39.410.010.29.48.38.39.19.69.910.310.510.811.010.811.211.311.511.812.112.312.112.613.413.610.610.49.1

us-gaap:AdjustmentsForNewAccountingPronouncements, slg:CumulativeEffectPeriodOfAdoption

us-gaap:AccountingStandardsUpdate201613, slg:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2020-01-01
Value39
Percentage of RetainedEarningsAccumulatedDeficit0.0
Percentage of Assets0.0
Percentage of Assets us-gaap:AccountingStandardsUpdate201613 slg:CumulativeEffectPeriodOfAdoptionAdjustment0.0

Treasury Stock Value

us-gaap:TreasuryStockValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value124124124124124124124124124124124124124124124101010335325325320320320320317316316322322319319319308307307306303302
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.91.00.90.90.91.00.90.90.90.90.80.80.80.80.80.10.10.11.71.91.91.91.91.92.12.12.22.22.22.22.22.32.32.32.32.42.72.72.9

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value-80-28-40-28-4153632281814141622-14-16-17-8-15-10-11-6-2-6-14-15-19-18-26-29-29-28-24-28-24-21-13-22-33
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.6-0.2-0.3-0.2-0.00.10.30.20.20.10.10.10.10.1-0.1-0.1-0.1-0.0-0.1-0.1-0.1-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.1-0.2-0.3

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value-80-28-40-28-41518
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.6-0.2-0.3-0.2-0.00.10.1
Percentage of Assets srt:Subsidiaries-0.6-0.2-0.3-0.2-0.00.10.1

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value427781155621237115194131102197116125135259114203891429011310018888102567966
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax13.425.026.049.720.539.123.250.431.336.527.549.630.833.632.542.025.147.820.734.823.029.325.848.723.127.716.823.926.6

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value427781155621237115194
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax13.425.026.049.720.539.123.250.431.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value-129355225-174-291181232-18745682162-29329-2822781787338-279-1728-48823028-507-246-71-174-29430-60
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-41.2115.471.9-55.8-95.957.275.5-62.4151.122.743.4-73.77.9-75.566.8289.574.4-65.7-400.1-119.458.17.4-130.0-63.6-18.8-47.2-86.79.3-24.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-129355225-174-291181232-187456
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-41.2115.471.9-55.8-95.957.275.5-62.4151.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value466-407-331-35246-284-42437-422-327-295-1014230-284-2087-392871667230-271-113351-81224102232-209-182
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax148.6-132.3-105.7-11.480.9-89.9-138.212.6-140.0-90.6-78.8-25.411.38.1-68.2-337.9-86.120.5385.956.4-68.6-29.490.2-21.058.827.668.6-62.7-72.7

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value466-407-331-35246-284-42437-422
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax148.6-132.3-105.7-11.480.9-89.9-138.212.6-140.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value427781155621237115194131102197116125135259114203891429011310018888102567966
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax13.425.026.049.720.539.123.250.431.336.527.549.630.833.632.542.025.147.820.734.823.029.325.848.723.127.716.823.926.6

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value427781155621237115194
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax13.425.026.049.720.539.123.250.431.3
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Net Income Loss

us-gaap:NetIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value118213616447-579110710531421115473713726105167-35476068239149404027262725110331014534881411914422
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax37.76.911.852.715.6-18.129.935.635.08.811.43.04.012.89.122.25.924.738.7-8.611.915.717.561.839.310.911.27.57.17.87.131.79.83.14.7177.626.55.637.357.58.8

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value124223817349-609611211033441215
Percentage of NetIncomeLoss105.2104.7104.7105.0104.8106.0105.2105.2105.0104.1104.3103.5103.2
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax39.77.212.355.316.4-19.231.537.536.79.111.93.14.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value127244017352-58991151133845160534314932114176-295565732501564531302811835165499312415026
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax40.47.913.055.517.3-18.432.338.537.710.612.24.00.214.410.424.17.126.940.9-7.114.016.918.964.641.112.58.68.27.933.910.45.3182.728.139.059.810.4

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value127244017352-5899115113
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax40.47.913.055.517.3-18.432.338.537.7
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Depreciation Depletion And Amortization

us-gaap:DepreciationDepletionAndAmortization



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-06-302010-03-31
Value706773727174737172889513698108117432187114153205114104101100938580635555
Percentage of DepreciationDepletionAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value706773727174737172
Percentage of DepreciationDepletionAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value-129355225-174-291181232-18745682162-29329-2822781787338-279-1728-48823028-507-246-71-174-29430-60
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-41.2115.471.9-55.8-95.957.275.5-62.4151.122.743.4-73.77.9-75.566.8289.574.4-65.7-400.1-119.458.17.4-130.0-63.6-18.8-47.2-86.79.3-24.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-129355225-174-291181232-187456
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax-41.2115.471.9-55.8-95.957.275.5-62.4151.1
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Payments To Acquire Property Plant And Equipment

Payments To Acquire Investments

us-gaap:PaymentsToAcquireInvestments



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value223329343048374229814524024223271101172957421217419616410615016111582195
Percentage of PaymentsToAcquireInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value223329343048374229
Percentage of PaymentsToAcquireInvestments100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value466-407-331-35246-284-42437-422-327-295-1014230-284-2087-392871667230-271-113351-81224102232-209-182
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax148.6-132.3-105.7-11.480.9-89.9-138.212.6-140.0-90.6-78.8-25.411.38.1-68.2-337.9-86.120.5385.956.4-68.6-29.490.2-21.058.827.668.6-62.7-72.7

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value466-407-331-35246-284-42437-422
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax148.6-132.3-105.7-11.480.9-89.9-138.212.6-140.0
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax srt:Subsidiaries0.00.00.00.00.00.00.00.00.0

Repayments Of Long Term Debt

Payments Of Dividends

us-gaap:PaymentsOfDividends



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value7975767777767678818183848479787878656464625251515138281512
Percentage of PaymentsOfDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value807979808179808285
Percentage of PaymentsOfDividends101.6104.9104.8104.8104.7104.6104.9104.9104.7

Payments Of Dividends

us-gaap:PaymentsOfDividends



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value7975767777767678818183848479787878656464625251515138281512
Percentage of PaymentsOfDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value807979808179808285
Percentage of PaymentsOfDividends101.6104.9104.8104.8104.7104.6104.9104.9104.7

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2192096575342193534238245613821100000
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value21920965753421935342382
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0

Repayments Of Long Term Debt

Debt Instrument Interest Rate Stated Percentage

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

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312010-12-312009-12-31
Value1111111111111111111111111111110111
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312010-12-312009-12-31
Value102.32102.36103.24103.31103.5135.54101.98101.43101.37101.4899.599.4599.1898.4497.1896.3295.5995.5290.389.6689.1987.9885.6585.5384.8983.2479.2578.176.8175.0573.563.3758.8556.74
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod

slg:RestrictedStockAwards



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value8320.098700.021650.00.06000.010000.0-31750.033450.00.0300.00.084250.07050.06500.01000.0137000.03000.0450.02603.09550.00.00.00.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod100.0100.0100.00.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:PlanName

slg:DeferredStockCompensationPlanForDirectors



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value11966.01442.01563.01366.014298.01097.01039.01291.010211.01217.01103.01087.09320.0886.0860.0957.06319.0709.0703.02328.05613.0679.02652.0-1282.07256.00.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod143.81.57.20.0238.30.010.4-4.130.50.00.0362.30.01.112.214.7631.90.523.4517.3215.67.10.00.00.00.0

Share Based Compensation

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value3813963963963960
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value3813963963963960
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.00.0

Cash And Cash Equivalents Period Increase Decrease

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value621241216241295279258379378250349380539369
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value621241216241295279258379378250369488
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

slg:AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue



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
Value0.00.0-100000.0-100000.0-100000.0-600000.0-100000.0-100000.0-200000.0-400000.0-100000.00.0-100000.00.0-100000.0500000.037000.00.0100000.0100000.01000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.00.0100.0100.0100.0

slg:ConsolidationOfJointVentureInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302013-03-312012-03-31
Value32500310301310000025318
Percentage of ConsolidationOfJointVentureInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value32500310
Percentage of ConsolidationOfJointVentureInterest100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value32500310
Percentage of ConsolidationOfJointVentureInterest100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302013-03-312012-03-31
Value32500310301310000025318
Percentage of ConsolidationOfJointVentureInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:DebtAndEquitySecuritiesCreditLossExpenseReversal



Period End2020-03-31
Value8
Percentage of DebtAndEquitySecuritiesCreditLossExpenseReversal100.0

slg:DebtAndPreferredEquityReserves



Period End2020-03-312019-03-31
Value40
Percentage of DebtAndPreferredEquityReserves100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value40
Percentage of DebtAndPreferredEquityReserves100.00.0

us-gaap:StatementGeographical, us-gaap:CreditFacility

slg:DebtInstrumentNumberofExtensionOptions

slg:A185Broadway, us-gaap:ConstructionLoans



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value2.00.00.00.02.0
Percentage of DebtInstrumentNumberofExtensionOptions100.00.00.00.0100.0

slg:A410TenthAvenue, us-gaap:ConstructionLoans



Period End2020-03-31
Value2.0
Percentage of DebtInstrumentNumberofExtensionOptions100.0

us-gaap:StatementGeographical, us-gaap:LongtermDebtType, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:OneVanderbilt, us-gaap:ConstructionLoans, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value2.00.00.00.02.0
Percentage of DebtInstrumentNumberofExtensionOptions100.00.00.00.0100.0

slg:DeferredCompensationPlanAndStockAwardNet



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312012-03-312011-03-31
Value5-5-5-4-4-4-331-60-1000-2000-3000-1-10-2
Percentage of DeferredCompensationPlanAndStockAwardNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value5-5-5-4-4-4-3
Percentage of DeferredCompensationPlanAndStockAwardNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value5-5-5-4-4-4-3
Percentage of DeferredCompensationPlanAndStockAwardNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312012-03-312011-03-31
Value5-5-5-4-4-4-331-60-1000-2-1001000100
Percentage of DeferredCompensationPlanAndStockAwardNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.099.0100.0100.0100.0-1316.75300.0100.0-38.1-64.9359.3317.1-90.9-4.4-19.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

slg:DeferredCompensationPlanAndStockAwardShares

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-33000.0-21000.0-3000.020000.0-13000.01000.019000.0
Percentage of DeferredCompensationPlanAndStockAwardShares100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value-33000.0-21000.0-3000.020000.0-13000.01000.019000.081000.0-2000.0-2000.010000.084000.08000.0-21000.025000.0140000.0
Percentage of DeferredCompensationPlanAndStockAwardShares100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.00.00.00.00.0

slg:DeferredLoanCostsAndCapitalizedLeaseObligation



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value061136100071301731190466403851331
Percentage of DeferredLoanCostsAndCapitalizedLeaseObligation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value06113610
Percentage of DeferredLoanCostsAndCapitalizedLeaseObligation100.0100.0100.0100.0100.0100.0100.0

slg:DistributedEarningsDiluted



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value448000.00.0164000.00.0125000.055000.042000.0109000.0
Percentage of DistributedEarningsDiluted100.00.0100.00.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value448000.00.0164000.00.033000.055000.042000.0
Percentage of DistributedEarningsDiluted100.00.0100.00.026.4100.0100.0

slg:DistributionToNoncontrollingInterestOperatingPartnership



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value13333333333333332222221210000
Percentage of DistributionToNoncontrollingInterestOperatingPartnership100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:DistributionsPreferredUnits

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value323332233513-14
Percentage of DistributionsPreferredUnits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3333333
Percentage of DistributionsPreferredUnits100.0100.0100.0100.0137.9123.7122.7

slg:DistributionsToNoncontrollingInterestsOtherPartnerships



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value00000610074400411761011011214723
Percentage of DistributionsToNoncontrollingInterestsOtherPartnerships100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value000006100
Percentage of DistributionsToNoncontrollingInterestsOtherPartnerships100.00.0100.0100.0100.0100.0100.0100.0100.0

slg:FinanceLeaseCost



Period End2020-03-312019-03-31
Value21
Percentage of FinanceLeaseCost100.0100.0

slg:FinancingReceivableAllowanceForCreditLossesWriteOffsAndReclassifications



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312014-12-312014-09-302014-06-302014-03-31
Value000042-201
Percentage of FinancingReceivableAllowanceForCreditLossesWriteOffsAndReclassifications0.00.00.00.0100.0100.0100.00.0100.0

slg:FinancingReceivablePortfolioSegmentsNumber



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312013-03-312012-03-31
Value1.00.00.00.01.00.00.00.01.00.00.00.01.00.00.00.01.00.00.00.01.01.01.0
Percentage of FinancingReceivablePortfolioSegmentsNumber100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.00.00.00.0100.0100.0100.0

slg:IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value127244017352-58994747554435512642-7085620-2942422758513037293310821112678
Percentage of IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, slg:RealEstateSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value111-9614021-95621314174-1811-13-33-112-3918-22-6569-1023
Percentage of IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment87.5-39.915.181.140.9163.562.927.929.631.010.9-51.822.8-51.0-78.7159.4-442.831.7-107.1219.316.021.4-38.339.6

us-gaap:OperatingSegments, slg:StructuredFinanceSegment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value153334323137363433373954393976414738433535333833
Percentage of IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment12.5139.984.918.959.1-63.537.172.170.469.089.1151.877.2151.0178.7-59.4542.868.3207.1-119.384.078.6138.358.3

slg:IncreaseDecreaseInAccruedLiabilitiesAndOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value-13-441318-12-16-2318-13125-16-75-13-202233-20-25414-104-512
Percentage of IncreaseDecreaseInAccruedLiabilitiesAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-13-441318-12-16-2318
Percentage of IncreaseDecreaseInAccruedLiabilitiesAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:IncreaseDecreaseInOperatingLeaseLiability



Period End2020-03-312019-03-31
Value-2-2
Percentage of IncreaseDecreaseInOperatingLeaseLiability100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value-2-2
Percentage of IncreaseDecreaseInOperatingLeaseLiability100.0100.0

slg:IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value40444044404440443030303332233311111
Percentage of IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:IncrementalCommonUnitsAttributabletoSharebasedPaymentArrangements

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value483000.0383000.0164000.0167000.0164000.04000.0219000.0201000.053000.0
Percentage of IncrementalCommonUnitsAttributabletoSharebasedPaymentArrangements100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:InterestExpenseNet



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value37484750555347656465647289948884757580827880828381858280756865565656
Percentage of InterestExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value37484750555347
Percentage of InterestExpenseNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value86929396889189615955
Percentage of InterestExpenseNet230.2192.5198.7191.2160.1170.9187.393.092.184.3

us-gaap:ConsolidatedEntities

slg:MinorityInterestIncreaseDecreaseFromFairValueAdjustment

srt:PartnershipInterest



Period End2020-03-31
Value-38
Percentage of MinorityInterestIncreaseDecreaseFromFairValueAdjustment100.0

us-gaap:ConsolidatedEntities

slg:NetIncomeLossAllocatedToCommonUnitholders

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value121183416946-64931091072940811
Percentage of NetIncomeLossAllocatedToCommonUnitholders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value114163316043-61881031012738
Percentage of NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value120173416945-6492108106
Percentage of NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic105.4106.2105.2105.2105.2105.6105.4105.4105.2

slg:NonCashLeaseExpense



Period End2020-03-312019-03-31
Value33
Percentage of NonCashLeaseExpense100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value33
Percentage of NonCashLeaseExpense100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

slg:NoncontrollingInterestAccruedDividendsOnPreferredUnits

srt:Subsidiaries, us-gaap:PreferredStock



Period End2020-03-31
Value2
Percentage of NoncontrollingInterestAccruedDividendsOnPreferredUnits100.0

us-gaap:ConsolidatedEntities

slg:NoncontrollingInterestDecreasefromDistributionstoOtherNoncontrollingInterestHolders

srt:PartnershipInterest



Period End2020-03-31
Value1
Percentage of NoncontrollingInterestDecreasefromDistributionstoOtherNoncontrollingInterestHolders100.0

slg:OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value221249246238246249
Percentage of OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:OperatingPartnershipNoncontrollingInterestFairValueAdjustment

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3818-28142826203
Percentage of OperatingPartnershipNoncontrollingInterestFairValueAdjustment100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:OtherComprehensiveIncomeLossNetofTaxLessPortionAttributabletoNoncontrollingInterest

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-52-11-24-19349
Percentage of OtherComprehensiveIncomeLossNetofTaxLessPortionAttributabletoNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-52-11-24-19349
Percentage of OtherComprehensiveIncomeLossNetofTaxLessPortionAttributabletoNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0

slg:PaymentsForAcquisitionDepositsAndDeferredPurchasePrice



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value050-440-1-13
Percentage of PaymentsForAcquisitionDepositsAndDeferredPurchasePrice0.0100.00.0100.0100.00.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value050-440-1-13
Percentage of PaymentsForAcquisitionDepositsAndDeferredPurchasePrice0.0100.00.0100.0100.00.0100.0100.0100.0

slg:PaymentsForProceedsFromOtherInvestments



Period End2020-03-312019-03-31
Value41
Percentage of PaymentsForProceedsFromOtherInvestments100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value41
Percentage of PaymentsForProceedsFromOtherInvestments100.0100.0

slg:PaymentsForRepurchaseOfPartnershipUnits



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value180015000
Percentage of PaymentsForRepurchaseOfPartnershipUnits100.0100.0100.0100.00.00.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value180015000
Percentage of PaymentsForRepurchaseOfPartnershipUnits100.0100.0100.0100.00.00.00.0

slg:PaymentsToAcquireLandBuildingsAndImprovements



Period End2020-03-312019-03-31
Value10139
Percentage of PaymentsToAcquireLandBuildingsAndImprovements100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value10139
Percentage of PaymentsToAcquireLandBuildingsAndImprovements100.0100.0

slg:ProceedsFromEquityMethodInvestmentDividendsOrDistributions



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value53172123293614218555372410669594034577185725-16-95-8
Percentage of ProceedsFromEquityMethodInvestmentDividendsOrDistributions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value531721232936142
Percentage of ProceedsFromEquityMethodInvestmentDividendsOrDistributions100.0100.0100.0100.0100.0100.0100.0

slg:ProceedsFromNoncontrollingInterestsInOtherPartnerships



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value352200310301310000038022610318
Percentage of ProceedsFromNoncontrollingInterestsInOtherPartnerships100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value352200310
Percentage of ProceedsFromNoncontrollingInterestsInOtherPartnerships100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value118361624791107105344112-2493814028107168-28526270241151293492
Percentage of ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value00-200002-10-17103120651111213
Percentage of ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships-0.2-1.7-1.30.5-0.10.20.27.2-3.66.2728.22.82.22.46.82.40.4-23.111.22.52.40.81.09.93.13.9

us-gaap:RetainedEarnings



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value1183616447911071053142473713726105167-35476068239149263388
Percentage of ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships100.2101.7101.399.5100.199.899.892.8103.697.297.897.693.297.699.6123.188.897.597.699.299.090.196.996.1

us-gaap:ConsolidatedEntities

slg:ProfitLossLessPreferredDistributions

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value118361624791107105
Percentage of ProfitLossLessPreferredDistributions100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value118361644791107105
Percentage of ProfitLossLessPreferredDistributions100.2101.7101.399.5100.199.899.8

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value00-20000
Percentage of ProfitLossLessPreferredDistributions-0.2-1.7-1.30.5-0.10.20.2

slg:PurchasePriceFairValueAdjustmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value00367-20-3
Percentage of PurchasePriceFairValueAdjustmentGainLoss0.00.0100.0100.0100.00.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value00367-20-3
Percentage of PurchasePriceFairValueAdjustmentGainLoss0.00.0100.0100.0100.00.0100.0

slg:PurchasePriceFairValueAdjustmentGross



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302013-09-302013-06-302012-09-302011-09-302011-06-30
Value00367-20-31149000040000-4710-200475
Percentage of PurchasePriceFairValueAdjustmentGross0.00.0100.0100.0100.00.0100.0100.0100.00.00.00.00.0100.00.00.00.0100.0100.00.0100.00.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value00367-20-31149
Percentage of PurchasePriceFairValueAdjustmentGross0.00.0100.0100.0100.00.0100.0100.0100.0

slg:ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease



Period End2020-03-312019-03-31
Value38-28
Percentage of ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value38-28
Percentage of ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-03-31
Value38-28
Percentage of ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease100.0100.0

us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings



Period End2020-03-312019-03-31
Value38-28
Percentage of ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease100.0100.0

slg:RemovalofFullyDepreciatedRealEstateAssets



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
Value01201484410645329884241000
Percentage of RemovalofFullyDepreciatedRealEstateAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value012014844106
Percentage of RemovalofFullyDepreciatedRealEstateAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value10111111244644015634510814556406322235766
Percentage of RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments



Period End2020-03-312019-03-31
Value151218
Percentage of RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value151218
Percentage of RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments100.0100.0

slg:ReversalOfAssetsHeldForSale



Period End2020-03-312019-03-31
Value3910
Percentage of ReversalOfAssetsHeldForSale100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value3910
Percentage of ReversalOfAssetsHeldForSale100.00.0

slg:SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value-360004
Percentage of SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease100.00.00.00.0100.0

slg:SellerFinancedPurchases



Period End2020-03-312019-03-31
Value1000
Percentage of SellerFinancedPurchases100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value1000
Percentage of SellerFinancedPurchases100.00.0

us-gaap:AwardType

slg:ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantsInPeriodFairValue

slg:LongTermIncentivePlanUnits



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
Value341600411002000020600270002592119
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantsInPeriodFairValue100.0100.00.00.0100.0100.00.00.0100.00.00.00.0100.0100.00.0100.0100.00.00.00.0100.0100.0100.0100.0100.0

slg:RestrictedStockAwards



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value081001-330009000150001000
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantsInPeriodFairValue2.053.30.00.01.10.00.015.70.00.00.0132.90.098.20.30.00.00.01.311.90.00.00.0

slg:TotalCostsAndExpensesIncludingNonoperatingIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value247252263258260267265258258314333365332347369693456370414442358347344336335336323327342316316293276263239238241
Percentage of TotalCostsAndExpensesIncludingNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value247252263258260267265258258314333365332
Percentage of TotalCostsAndExpensesIncludingNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value301301308308320317311321321241206211211
Percentage of TotalCostsAndExpensesIncludingNonoperatingIncomeExpense121.9119.3117.2119.5123.1118.5117.4124.3124.376.761.757.963.4

slg:TransactionRelatedCosts



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value0000000000122115312212-211111012341
Percentage of TransactionRelatedCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value65000.044000.0261000.055000.0163000.0348000.0162000.0
Percentage of TransactionRelatedCosts100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:WeightedAverageNumberofUnitsOutstandingDiluted

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value82868787909295
Percentage of WeightedAverageNumberofUnitsOutstandingDiluted100.0100.0100.0100.0100.0100.0100.0

srt:MortgageLoansOnRealEstateInterestRate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.0787-0.00470000000000001-0.00109999999999998990.00209999999999999080.0879
Percentage of MortgageLoansOnRealEstateInterestRate100.0100.0100.0100.0100.0

us-gaap:MortgageLoansOnRealEstateLoanType

slg:PreferredEquityInvestmentsInMortgageLoans



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.09870.00119999999999999270.00.00769999999999999850.0874
Percentage of MortgageLoansOnRealEstateInterestRate125.4-25.5-0.0366.799.4

us-gaap:AffiliateCosts



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value3552443554656365436543444443433333
Percentage of AffiliateCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3552443
Percentage of AffiliateCosts100.0100.0100.0100.0100.0100.2100.0

us-gaap:AwardType

us-gaap:AllocatedShareBasedCompensationExpense

slg:RestrictedStockAwards



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value233233332221112111122221
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PerformanceShares



Period End2020-03-312019-09-302019-03-312018-09-30
Value7382
Percentage of AllocatedShareBasedCompensationExpense249.295.6234.572.1

us-gaap:AwardType, us-gaap:PlanName

us-gaap:EmployeeStockOption, slg:ThirdAmendmentandRestated2005StockOptionandIncentivePlan



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
Value0000011111210221221122222
Percentage of AllocatedShareBasedCompensationExpense0.720.519.120.517.60.034.551.351.00.082.676.80.0133.1131.3140.199.2117.2102.6101.3103.387.977.285.689.7

us-gaap:PlanName

slg:DeferredStockCompensationPlanForDirectors



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value100010002000100010001000
Percentage of AllocatedShareBasedCompensationExpense61.45.86.46.855.70.03.13.270.20.04.18.179.810.65.314.879.35.35.416.067.14.23.94.3

us-gaap:AmortizationOfAboveAndBelowMarketLeases



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value101111112
Percentage of AmortizationOfAboveAndBelowMarketLeases100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AmortizationOfFinancingCosts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value2332222334434447777566653444433223212
Percentage of AmortizationOfFinancingCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value233222233
Percentage of AmortizationOfFinancingCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value4444544755476
Percentage of AmortizationOfFinancingCosts192.6158.8142.5176.3190.2175.2169.0207.3144.6117.1100.5217.3136.6

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value111101110100100000000000000000
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1111011
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalExpendituresIncurredButNotYetPaid



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value0-3109-160015-210711-7-618-6-301701-299117
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0-3109-160015
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value37924-24-541620-1211128-99-31-158169
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value37924-24-541620-1211128
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockDividendsPerShareDeclared



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value0.2950.850.850.850.81250.81250.81250.8150.7750.7750.780.77999999999999980.720.720.720.720.60.60.60.60000000000000010.50.50.50.330.330.330.330.250.250.250.250.10.10.10.10.10.10.10.10.375
Percentage of CommonStockDividendsPerShareDeclared100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0.2950.850.850.850.81250.81250.8125
Percentage of CommonStockDividendsPerShareDeclared100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType, slg:RealEstateByLocation

us-gaap:ConcentrationRiskPercentage1

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:A11MadisonAve



Period End2020-03-31
Value0.083
Percentage of ConcentrationRiskPercentage1100.0

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:AvenueOfTheAmericas1185



Period End2020-03-31
Value0.085
Percentage of ConcentrationRiskPercentage1102.4

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:Broadway1515



Period End2020-03-31
Value0.068
Percentage of ConcentrationRiskPercentage181.9

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:East220Street42



Period End2020-03-31
Value0.062
Percentage of ConcentrationRiskPercentage174.7

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:LexingtonAvenue420



Period End2020-03-31
Value0.075
Percentage of ConcentrationRiskPercentage190.4

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:LexingtonAvenue485



Period End2020-03-31
Value0.053
Percentage of ConcentrationRiskPercentage163.9

slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, slg:ParkAvenue280



Period End2020-03-31
Value0.054
Percentage of ConcentrationRiskPercentage165.1

us-gaap:MajorCustomers, us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType

slg:Tenant1, slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk



Period End2020-03-312019-03-31
Value0.0550.082
Percentage of ConcentrationRiskPercentage166.30.0

us-gaap:MajorCustomers, us-gaap:ConcentrationRiskByBenchmark, us-gaap:ConcentrationRiskByType, us-gaap:SubsequentEventType

slg:CreditSuisse, slg:AnnualizedRent, us-gaap:CustomerConcentrationRisk, us-gaap:SubsequentEvent



Period End2020-01-31
Value0.033
Percentage of ConcentrationRiskPercentage10.0

us-gaap:ConsolidatedEntities, us-gaap:FederalHomeLoanBankAdvancesOption, us-gaap:VariableRate

us-gaap:DebtInstrumentBasisSpreadOnVariableRate1

slg:TiconderogaInsuranceCompany, slg:LIBORPlus19BasisPoints, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-31
Value0.0019
Percentage of DebtInstrumentBasisSpreadOnVariableRate1100.0

us-gaap:DebtInstrument, us-gaap:LongtermDebtType, us-gaap:VariableRate

slg:TermLoanBMaturityNovember212024, slg:TermLoan, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-312019-03-312018-03-31
Value0.010.01650.0165
Percentage of DebtInstrumentBasisSpreadOnVariableRate1526.30.00.0

us-gaap:DebtInstrument, us-gaap:SubsequentEventType

slg:FHLBFacilityFebruary2020, us-gaap:SubsequentEvent



Period End2020-02-24
Value0.0026
Percentage of DebtInstrumentBasisSpreadOnVariableRate10.0

slg:FHLBFacilityJanuary2020, us-gaap:SubsequentEvent



Period End2020-01-31
Value0.00165
Percentage of DebtInstrumentBasisSpreadOnVariableRate10.0

us-gaap:Range, us-gaap:DebtInstrument, us-gaap:LongtermDebtType, us-gaap:VariableRate

srt:Maximum, slg:TermLoanBMaturityNovember212024, slg:TermLoan, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-312019-03-31
Value0.01650.0245
Percentage of DebtInstrumentBasisSpreadOnVariableRate1868.40.0

srt:Minimum, slg:TermLoanBMaturityNovember212024, slg:TermLoan, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-312019-03-31
Value0.00850.015
Percentage of DebtInstrumentBasisSpreadOnVariableRate1447.40.0

us-gaap:DepreciationAndAmortization



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value68647069687170676984911339410411242517910614619910897949489878280837777736567565559
Percentage of DepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value686470696871706769
Percentage of DepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value989810010310410310111110580616571
Percentage of DepreciationAndAmortization144.4154.4143.0149.3152.7144.6143.5164.2151.495.867.049.675.6

us-gaap:DilutiveSecuritiesEffectOnBasicEarningsPerShareOther



Period End2020-03-312019-03-312013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value6200030011112
Percentage of DilutiveSecuritiesEffectOnBasicEarningsPerShareOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:DistributedEarnings

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value010000000
Percentage of DistributedEarnings100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value226969706969727575767778727271715959595847474730228
Percentage of DividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value226969706969727575767778727271715959595847474730228
Percentage of DividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value33333333333333333333333333367777777777777
Percentage of DividendsPreferredStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value33333333333333333333333777
Percentage of DividendsPreferredStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value000001111212111111111111101101100100
Percentage of EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquityMethodInvestmentDividendsOrDistributions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value00000002707655468710615586764210
Percentage of EquityMethodInvestmentDividendsOrDistributions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value000000027
Percentage of EquityMethodInvestmentDividendsOrDistributions100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-312010-09-302010-06-30
Value00059171677072-6011320033901500016110470-3019-4970310126
Percentage of EquityMethodInvestmentRealizedGainLossOnDisposal0.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value00059171677072-601132
Percentage of EquityMethodInvestmentRealizedGainLossOnDisposal0.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-18-22-23-18-12-12-6-60192-15
Percentage of EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:EquityMethodInvestmentSummarizedFinancialInformationRevenue

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value282279286290307304304314320261216210216
Percentage of EquityMethodInvestmentSummarizedFinancialInformationRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinanceLeaseInterestExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value100008000
Percentage of FinanceLeaseInterestExpense100.0100.0100.0100.0100.0100.00.00.0100.0

us-gaap:GainLossOnSaleOfPropertiesNetOfApplicableIncomeTaxes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value72-1930-1-36-2-1423
Percentage of GainLossOnSaleOfPropertiesNetOfApplicableIncomeTaxes100.0100.0100.00.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value72-1930-1-36-2-1423
Percentage of GainLossOnSaleOfPropertiesNetOfApplicableIncomeTaxes100.0100.0100.00.0100.0100.0100.0100.0100.0

us-gaap:GainsLossesOnSalesOfInvestmentRealEstate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value72-1930-1-36-2-1423760-3027019613161590000
Percentage of GainsLossesOnSalesOfInvestmentRealEstate100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value72-1930-1-36-2-1423760-30
Percentage of GainsLossesOnSalesOfInvestmentRealEstate100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:IncomeLossFromEquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value-12-11-9-7-5-204474360-3510232456862-351170-1-22871015
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-12-11-9-7-5-20447436
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-12-11-9-7-5-20447436
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccountsReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value44-26-34-3-3-11330-1-223-7-2113-7-9136-11-70-10
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value44-26-34-3-3-11
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredLeasingFees



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value832619131214971071492315181314102411356644777
Percentage of IncreaseDecreaseInDeferredLeasingFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value83261913121497
Percentage of IncreaseDecreaseInDeferredLeasingFees100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredLiabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value7-718-1110-516-34-825325-1722-2117-1820-1114-1420-111419731
Percentage of IncreaseDecreaseInDeferredLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value7-718-1110-516-34
Percentage of IncreaseDecreaseInDeferredLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDueFromRelatedPartiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value41-4-516-6-34-104311-240000-14-111133-2-5
Percentage of IncreaseDecreaseInDueFromRelatedPartiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value41-4-516-6-34
Percentage of IncreaseDecreaseInDueFromRelatedPartiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value48-2846-3940-4347-4347-3558-4645-4035-5146-6255-4938-4535-3232212471
Percentage of IncreaseDecreaseInOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value48-2846-3940-4347-4347
Percentage of IncreaseDecreaseInOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value483000.0383000.0164000.0167000.0164000.04000.0219000.0201000.053000.0-3000.0244000.0270000.0304000.024000.0413000.0316000.0234000.010000.0407000.00.0653000.0-54000.0387000.0514000.0520000.020000.0236000.0224000.0216000.0330000.0369000.0380000.0473000.0520000.0437000.0344000.0420000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestCostsIncurredCapitalized



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value20151210876666565677784764233322101
Percentage of InterestCostsIncurredCapitalized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestIncomeExpenseNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value-37336-48-47-50365-55-53-47453-65646564728994-88-84-75-75-80-82-78-80-82-83-81-85-82-80-74-68-64
Percentage of InterestIncomeExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestIncomeOperating



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value000200000000000100000000000000000000
Percentage of InterestIncomeOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value110000000000-1-1-1-5-2-2-3-3-32111111-1-3-3-3-3-3-3-3-3
Percentage of InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentRisk

us-gaap:InterestRateSwap



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value0000000000-1-1-4-2-2-2-2-221100000
Percentage of InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet50.535.446.059.255.332.999.731.564.071.073.772.588.786.089.490.589.289.295.397.869.635.234.320.027.2-27.4

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value000000000-1000
Percentage of InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet49.528.564.654.040.837.144.767.10.3481.4-68.5-36.029.0

us-gaap:InvestmentIncomeInterestAndDividend



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value38425151505748494545476040387544544449454241433954444652273326181567842020
Percentage of InvestmentIncomeInterestAndDividend100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value384251515057484945
Percentage of InvestmentIncomeInterestAndDividend100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument

us-gaap:LineOfCreditFacilityCommitmentFeePercentage

us-gaap:RevolvingCreditFacility



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312013-03-31
Value0.0020.00.00.00.0020.00.00.00.002-0.00050.00.00.00250.00.00.00.00250.00.003
Percentage of LineOfCreditFacilityCommitmentFeePercentage100.00.00.00.0100.00.00.00.0100.0100.00.00.0100.00.00.00.0100.00.0100.0

us-gaap:Range, us-gaap:DebtInstrument

srt:Maximum, us-gaap:RevolvingCreditFacility



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.0030.00.00.00.003
Percentage of LineOfCreditFacilityCommitmentFeePercentage150.00.00.00.0150.0

srt:Minimum, us-gaap:RevolvingCreditFacility



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.001250.00.00.00.00125
Percentage of LineOfCreditFacilityCommitmentFeePercentage62.50.00.00.062.5

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value00001007440041174101121121472
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0000100
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0000100
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value00001007440041174101121121472
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MinorityInterestDecreaseFromRedemptions



Period End2020-03-312019-09-302019-06-302019-03-312015-12-312015-09-302015-06-302015-03-31
Value1025000173
Percentage of MinorityInterestDecreaseFromRedemptions100.0100.0100.00.00.00.0100.0100.0

us-gaap:ConsolidatedEntities

srt:PartnershipInterest



Period End2020-03-31
Value18
Percentage of MinorityInterestDecreaseFromRedemptions1181.6

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value1902516
Percentage of MinorityInterestDecreaseFromRedemptions100.00.0100.0100.00.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-30
Value300
Percentage of MinorityInterestDecreaseFromRedemptions203.3100.02.0

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

srt:Subsidiaries, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value1930015
Percentage of MinorityInterestDecreaseFromRedemptions1262.50.00.00.00.0

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-30
Value-1025
Percentage of MinorityInterestDecreaseFromRedemptions-103.30.098.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-09-302019-06-302015-12-312015-09-302015-06-302015-03-31
Value3000017-7
Percentage of MinorityInterestDecreaseFromRedemptions203.3100.02.00.00.0100.0-214.9

us-gaap:NoncontrollingInterest



Period End2020-03-312019-09-302019-06-302015-12-312015-09-302015-06-302015-03-31
Value-102500011
Percentage of MinorityInterestDecreaseFromRedemptions-103.30.098.00.00.00.0314.9

us-gaap:MortgageLoansOnRealEstateAmortizationOfPremium



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value161457316146271186246297263105
Percentage of MortgageLoansOnRealEstateAmortizationOfPremium100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentType

us-gaap:MortgageLoansOnRealEstateNewMortgageLoans

slg:DebtInvestmentsInMortgageLoans



Period End2020-03-31
Value246
Percentage of MortgageLoansOnRealEstateNewMortgageLoans100.0

slg:PreferredEquityInvestmentsInMortgageLoans



Period End2020-03-31
Value154
Percentage of MortgageLoansOnRealEstateNewMortgageLoans62.9

us-gaap:ConsolidatedEntities

us-gaap:NetIncomeLossNetOfTaxPerOutstandingLimitedPartnershipUnitDiluted

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.470.210.41.940.52-0.731.031.191.120.290.40.080.11
Percentage of NetIncomeLossNetOfTaxPerOutstandingLimitedPartnershipUnitDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:NetIncomeLossPerOutstandingLimitedPartnershipUnitBasicNetOfTax

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.470.210.41.940.52-0.731.031.191.120.290.40.080.11
Percentage of NetIncomeLossPerOutstandingLimitedPartnershipUnitBasicNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable



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
Value60182-34551100115036-1122841100
Percentage of NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:PartnershipInterest



Period End2020-03-31
Value6
Percentage of NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable100.0

us-gaap:NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable



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
Value000-2000002-10-171031206511111232
Percentage of NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value000-200000
Percentage of NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable



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
Value222222222222222222210
Percentage of NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value222222222
Percentage of NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance

srt:PartnershipInterest



Period End2020-03-31
Value3
Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

srt:Subsidiaries, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.00.00.01000000.00.0
Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance0.00.00.00.00.0

us-gaap:OperatingLeaseCost



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value788886988
Percentage of OperatingLeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value788886988
Percentage of OperatingLeaseCost100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-09-302019-03-312018-09-30
Value6654
Percentage of OperatingLeaseCost86.380.971.146.3

us-gaap:OperatingLeaseLeaseIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value222250248243238247250236239
Percentage of OperatingLeaseLeaseIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-03-312018-09-30
Value222248240250
Percentage of OperatingLeaseLeaseIncome100.0100.0100.5100.0

us-gaap:OperatingLeaseLeaseIncomeLeasePayments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value194217214215211215220209213
Percentage of OperatingLeaseLeaseIncomeLeasePayments100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingLeaseVariableLeaseIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value273132282731292726
Percentage of OperatingLeaseVariableLeaseIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-5310-12-23-18-20449
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty, us-gaap:StatementEquityComponents

us-gaap:CorporateJointVenture, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-6-2-4-6-6203
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax12.521.517.638.531.251.923.132.2

us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-42-9-19-11-14226
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax79.580.384.865.569.248.869.971.0

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-40000000
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax8.0-1.8-2.3-4.0-0.5-0.77.1-3.3

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value-5012-12-20-223
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value-5012-12-20-223
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value-5210-12-17-234
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentRisk

us-gaap:InterestRateSwap



Period End2020-03-312019-09-302019-03-312018-09-30
Value-45-10-112
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax86.480.769.049.4

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value-71-2-5-82
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax13.615.319.331.036.250.6

us-gaap:OtherComprehensiveIncomeLossNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-30
Value-5512-12-25-20-22341040-2-53720-87-50-5-43800730-43-2
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-5512-12-25-20-223410
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-30
Value-200-1-1-100000001000000000000000000
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:PartnershipInterest



Period End2020-03-31
Value-2
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest100.0

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-200-1-1-1000
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-52-11-24-1934940-2-53620-87-40-4-43803
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-52-11-24-1934940-2-53620-87-40-4-43803
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value-4000000000-4000-100-10-30100-110001-56
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-4000000
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value53151416141171314971511661079131618971122149559610697888
Percentage of OtherIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value53151416141171314
Percentage of OtherIncome100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherNoncashIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value-1-9154-9502-12103-20-4-8149144128-4151-11222-51
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-1-9154-9502-12
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:PartnersCapitalAccountDistributions

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value22696970696972
Percentage of PartnersCapitalAccountDistributions100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value22696970696972
Percentage of PartnersCapitalAccountDistributions100.0100.0100.0100.0100.0100.0100.0

us-gaap:PartnersCapitalAccountRedemptions



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value00000140106201319047143037536161700
Percentage of PartnersCapitalAccountRedemptions100.00.0100.00.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0000014010
Percentage of PartnersCapitalAccountRedemptions100.00.0100.00.0100.0100.00.0100.00.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

us-gaap:PartnersCapitalAccountUnitsSaleOfUnits

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1000.00.00.05000.00.015000.00.0
Percentage of PartnersCapitalAccountUnitsSaleOfUnits100.00.00.0100.00.0100.00.0

us-gaap:PaymentsForRepurchaseOfRedeemablePreferredStock



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
Value193001500000000002000002000
Percentage of PaymentsForRepurchaseOfRedeemablePreferredStock100.0100.00.00.0100.0100.00.0100.0100.0100.00.0100.00.0100.0100.0100.0100.00.00.00.0100.0100.00.00.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value19300150000
Percentage of PaymentsForRepurchaseOfRedeemablePreferredStock100.0100.00.00.0100.0100.00.0100.0100.0

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value400033-3030003
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.00.00.0100.0100.0100.00.0100.00.00.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value400030003
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.00.00.0100.00.0-0.00.0100.0

us-gaap:PaymentsToAcquireCommercialRealEstate



Period End2020-03-312019-03-31
Value860
Percentage of PaymentsToAcquireCommercialRealEstate100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value860
Percentage of PaymentsToAcquireCommercialRealEstate100.00.0

us-gaap:PaymentsToAcquireEquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value814162473101442035127619858154418633182583164461511849105311
Percentage of PaymentsToAcquireEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8141624731014420351
Percentage of PaymentsToAcquireEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:Range, us-gaap:StatementClassOfStock

us-gaap:PreferredStockDividendRatePercentage

srt:Subsidiaries, srt:Minimum, us-gaap:SeriesAPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.750.00.00.75
Percentage of PreferredStockDividendRatePercentage100.00.00.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

srt:Subsidiaries, slg:SeriesKPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.0350.00.00.035
Percentage of PreferredStockDividendRatePercentage4.70.00.04.7

srt:Subsidiaries, slg:SeriesLPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.040.00.00.04
Percentage of PreferredStockDividendRatePercentage5.30.00.05.3

srt:Subsidiaries, slg:SeriesMPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.03750.00.00.0375
Percentage of PreferredStockDividendRatePercentage5.00.00.05.0

srt:Subsidiaries, slg:SeriesPPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.040.00.00.04
Percentage of PreferredStockDividendRatePercentage5.30.00.05.3

srt:Subsidiaries, slg:SeriesQPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.0350.00.00.035
Percentage of PreferredStockDividendRatePercentage4.70.00.04.7

srt:Subsidiaries, slg:SeriesRPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.0350.00.00.035
Percentage of PreferredStockDividendRatePercentage4.70.00.04.7

srt:Subsidiaries, slg:SeriesSPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.040.00.00.04
Percentage of PreferredStockDividendRatePercentage5.30.00.05.3

srt:Subsidiaries, slg:SeriesTPreferredUnits



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.02750.00.00.0275
Percentage of PreferredStockDividendRatePercentage3.70.00.03.7

srt:Subsidiaries, slg:SeriesUPreferredUnits



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.0450.00.00.045
Percentage of PreferredStockDividendRatePercentage6.00.00.06.0

srt:Subsidiaries, slg:SeriesVPreferredStock



Period End2020-03-312019-09-30
Value0.0350.0
Percentage of PreferredStockDividendRatePercentage4.70.0

srt:Subsidiaries, us-gaap:SeriesAPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.0350.00.00.035
Percentage of PreferredStockDividendRatePercentage4.70.00.04.7

srt:Subsidiaries, us-gaap:SeriesFPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.070.00.00.07
Percentage of PreferredStockDividendRatePercentage9.30.00.09.3

srt:Subsidiaries, us-gaap:SeriesGPreferredStock



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.0450.00.00.045
Percentage of PreferredStockDividendRatePercentage6.00.00.06.0

us-gaap:StatementClassOfStock

slg:SeriesIPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-08-31
Value0.0650.00.00.00.0650.00.00.00.0650.00.00.00.0650.00.00.00.0650.00.00.00.0650.00.00.00.0650.0650.065
Percentage of PreferredStockDividendRatePercentage8.70.00.00.08.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ConsolidatedEntities

us-gaap:PreferredStockDividendsAndOtherAdjustments

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value3333333333333
Percentage of PreferredStockDividendsAndOtherAdjustments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

us-gaap:PreferredStockDividendsPerShareCashPaid

srt:Subsidiaries, slg:SeriesKPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.8750.00.00.00.875
Percentage of PreferredStockDividendsPerShareCashPaid100.00.00.00.0100.0

srt:Subsidiaries, slg:SeriesLPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.00.00.00.01.0
Percentage of PreferredStockDividendsPerShareCashPaid114.30.00.00.0114.3

srt:Subsidiaries, slg:SeriesMPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.93750.00.00.00.9375
Percentage of PreferredStockDividendsPerShareCashPaid107.10.00.00.0107.1

srt:Subsidiaries, slg:SeriesPPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.00.00.00.01.0
Percentage of PreferredStockDividendsPerShareCashPaid114.30.00.00.0114.3

srt:Subsidiaries, slg:SeriesQPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.8750.00.00.00.875
Percentage of PreferredStockDividendsPerShareCashPaid100.00.00.00.0100.0

srt:Subsidiaries, slg:SeriesRPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.8750.00.00.00.875
Percentage of PreferredStockDividendsPerShareCashPaid100.00.00.00.0100.0

srt:Subsidiaries, slg:SeriesSPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.00.00.00.01.0
Percentage of PreferredStockDividendsPerShareCashPaid114.30.00.00.0114.3

srt:Subsidiaries, slg:SeriesTPreferredUnits



Period End2020-03-312019-09-302019-06-302019-03-31
Value0.68750.00.00.6875
Percentage of PreferredStockDividendsPerShareCashPaid78.60.00.078.6

srt:Subsidiaries, slg:SeriesUPreferredUnits



Period End2020-03-312019-09-302019-06-302019-03-31
Value1.1250.00.01.125
Percentage of PreferredStockDividendsPerShareCashPaid128.60.00.0128.6

srt:Subsidiaries, slg:SeriesVPreferredStock



Period End2020-03-312019-12-312019-09-30
Value0.8750.00.0
Percentage of PreferredStockDividendsPerShareCashPaid100.00.00.0

srt:Subsidiaries, us-gaap:SeriesAPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value35.00.00.00.035.0
Percentage of PreferredStockDividendsPerShareCashPaid4000.00.00.00.04000.0

srt:Subsidiaries, us-gaap:SeriesFPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value70.00.00.00.070.0
Percentage of PreferredStockDividendsPerShareCashPaid8000.00.00.00.08000.0

srt:Subsidiaries, us-gaap:SeriesGPreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.1250.00.00.01.125
Percentage of PreferredStockDividendsPerShareCashPaid128.60.00.00.0128.6

us-gaap:StatementClassOfStock

us-gaap:ProceedsFromIssuanceOfCommonStock

slg:DividendReinvestmentAndStockPurchasePlan



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302015-12-312015-09-302015-06-302015-03-312013-03-312012-03-31
Value0000000000000099099
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfSecuredDebt



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value1015327131710922512811199900177815252222714315991060150400148012198010840
Percentage of ProceedsFromIssuanceOfSecuredDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1015327131710922512811199
Percentage of ProceedsFromIssuanceOfSecuredDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromOtherDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value1125150420520730102045537579527765560180520385107539066577145380603155300458250
Percentage of ProceedsFromOtherDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value11251504205207301020455
Percentage of ProceedsFromOtherDebt100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromPaymentsToMinorityShareholders



Period End2020-03-312019-03-31
Value-10
Percentage of ProceedsFromPaymentsToMinorityShareholders100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-03-31
Value-10
Percentage of ProceedsFromPaymentsToMinorityShareholders100.00.0

us-gaap:ProceedsFromRealEstateAndRealEstateJointVentures



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value916901241433813235040952293203495031776139144580648546399148109523
Percentage of ProceedsFromRealEstateAndRealEstateJointVentures100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value9169012414338132350409
Percentage of ProceedsFromRealEstateAndRealEstateJointVentures100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromStockOptionsExercised



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value0000013940110282731311109401084102312
Percentage of ProceedsFromStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0000013940
Percentage of ProceedsFromStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForLoanAndLeaseLosses



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312013-09-302012-09-302012-03-312011-06-302011-03-312010-09-302010-06-30
Value11000510000000001-314
Percentage of ProvisionForLoanAndLeaseLosses100.00.00.00.0100.0100.00.00.00.00.00.00.00.00.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value1100051
Percentage of ProvisionForLoanAndLeaseLosses100.00.00.00.0100.2100.0

us-gaap:ProvisionForLoanLeaseAndOtherLosses



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-31
Value110000500000000003
Percentage of ProvisionForLoanLeaseAndOtherLosses100.00.00.00.00.0100.00.00.00.00.00.00.00.00.00.00.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-03-312018-12-31
Value11005
Percentage of ProvisionForLoanLeaseAndOtherLosses100.00.00.0100.0

us-gaap:RealEstateTaxExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value46474946464648454558646061606462615961565558555355555253535251444340353736
Percentage of RealEstateTaxExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value464749464646484545
Percentage of RealEstateTaxExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value53525351545756555735373534
Percentage of RealEstateTaxExpense114.5110.6107.4111.3116.2123.2116.3123.2124.960.858.157.757.2

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-1-10010000
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty, us-gaap:StatementEquityComponents

us-gaap:CorporateJointVenture, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-673000.0-205000.0532000.0478000.0251000.0228000.0140000.0-1000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax49.567.055.047.431.845.565.70.3

us-gaap:StatementEquityComponents

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-687000.0-101000.0435000.0530000.0538000.0273000.073000.0-310000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax50.533.045.052.668.254.534.399.7

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty

slg:AllianceBuildingServices



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value35524554655475737544654344444343333
Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty

slg:AllianceBuildingServices



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value900000.0900000.01000000.0900000.0900000.0900000.01000000.01000000.0900000.01000000.01000000.0800000.0900000.0800000.0900000.0900000.0900000.0900000.01000000.01000000.01000000.0900000.01000000.0900000.0800000.0900000.01000000.0800000.0800000.0800000.0800000.01000000.0100000.0600000.0500000.0
Percentage of RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RepaymentsOfOtherDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value3154855402308456604953955972776560567099424073120553058028580440199352693495
Percentage of RepaymentsOfOtherDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value315485540230845660495
Percentage of RepaymentsOfOtherDebt100.0100.0100.0100.0100.0100.0100.0

us-gaap:RepaymentsOfSecuredDebt



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-312010-03-31
Value1026811842151732813919612126803612215351279919274815131921485107871314812
Percentage of RepaymentsOfSecuredDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value10268118421517328139
Percentage of RepaymentsOfSecuredDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:RevenueFromRelatedParties

slg:RelatedPartyStephenLGreenInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-30
Value200000.0200000.0200000.0100000.0200000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0400000.0100000.0100000.0100000.0100000.0100000.0100000.0127200.0113600.0114300.0111600.0104800.0105000.096000.0118200.093000.0110000.089000.0113000.0
Percentage of RevenueFromRelatedParties100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1020003890000
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability100.00.00.00.0100.00.00.00.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1020003890000
Percentage of RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability100.00.00.00.0100.00.00.00.00.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod

slg:RestrictedStockAwards



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value13267.0400.03800.01750.05950.0800.03750.04550.00.00.00.050.00.030000.04600.02434.0817.02900.00.0334.01000.0434.01000.0300.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.00.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod

slg:RestrictedStockAwards



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value131602.01885.00.01100.0110274.00.01100.091014.02500.01450.082786.00.02500.0150.081172.00.02500.00.084581.01875.03875.01875.067418.0500.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue

slg:RestrictedStockAwards



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value120011200910080007000700040
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.00.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value5500.059450.012000.022500.05999.011201.034166.037234.018799.05001.03466.036633.025201.061902.08917.023400.015800.09700.011650.010000.08767.02967.026251.018317.08667.04000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value109.94.210000000000008-0.9800000000000042.019999999999996110.56-1.1200000000000045-0.359999999999999433.3100000000000023111.39-0.6199999999999903-0.4099999999999966-4.570000000000007127.2813.049999999999997-2.569999999999993-0.21000000000000796113.590.20000000000000284-2.260000000000005-2.8999999999999915103.57-0.17000000000000176.3900000000000013.320000000000007480.4967.64
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0.00.00.00.00.00.00.00.06000.03000.03000.0108000.060000.0335600.00.0105000.04500.0349336.028500.012000.00.093050.06000.00.03000.0201000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod0.00.00.00.00.00.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0.00.00.00.00.0-0.32000000000000740.92000000000000170.71000000000000888.91-2.950000000000003-0.040000000000006250.03000000000000113784.03-1.02.4800000000000043.01000000000000572.41-0.6400000000000006-0.100000000000008530.160000000000010875.271.990000000000009-0.54.7566.5250.22
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice0.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0.00.00.00.00.00.00.00.097.91-0.04000000000000625-0.060000000000002274-0.28999999999999204106.056.2099999999999940.04.90000000000000694.75-4.959999999999994-11.319999999999993128.820.013.0900000000000037.4500000000000030.098.5876.67
Percentage of ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice0.00.00.00.00.00.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesConversionOfUnits

us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302017-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1000.00.00.05000.00.015000.020000.0130000.032000.04000.0317000.051000.031000.065000.0168000.0
Percentage of StockIssuedDuringPeriodSharesConversionOfUnits100.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesDividendReinvestmentPlan

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value2000.00.02000.01000.00.00.01000.0
Percentage of StockIssuedDuringPeriodSharesDividendReinvestmentPlan100.00.0100.0100.00.00.0100.0

us-gaap:StatementEquityComponents

us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312015-09-302015-06-302015-03-31
Value2000.00.02000.01000.00.00.01000.00.01000.00.01000.01000.00.00.01000.00.0775000.0
Percentage of StockIssuedDuringPeriodSharesDividendReinvestmentPlan100.00.0100.0100.00.00.0100.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StatementClassOfStock

us-gaap:StockIssuedDuringPeriodSharesNewIssues

slg:DividendReinvestmentAndStockPurchasePlan



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value000000000000000000001
Percentage of StockIssuedDuringPeriodSharesNewIssues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0.00.00.00.00.0148434.0109134.054734.04000.0145916.08334.033792.0104151.035514.082160.057951.017250.047403.015199.017900.0136936.058363.012648.0122614.0154531.079036.0
Percentage of StockIssuedDuringPeriodSharesStockOptionsExercised0.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueConversionOfUnits



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value00000162013190471430375361617
Percentage of StockIssuedDuringPeriodValueConversionOfUnits100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0000010
Percentage of StockIssuedDuringPeriodValueConversionOfUnits100.0100.00.0100.00.0100.00.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0000010
Percentage of StockIssuedDuringPeriodValueConversionOfUnits100.0100.00.0100.00.0100.00.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value00000162013190471430375361617
Percentage of StockIssuedDuringPeriodValueConversionOfUnits100.0100.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueDividendReinvestmentPlan



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value0000000000000000009900000990
Percentage of StockIssuedDuringPeriodValueDividendReinvestmentPlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value166000.039000.0216000.047000.052000.022000.042000.0
Percentage of StockIssuedDuringPeriodValueDividendReinvestmentPlan100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value166000.039000.0216000.047000.052000.022000.042000.0
Percentage of StockIssuedDuringPeriodValueDividendReinvestmentPlan100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-03-31
Value0000000000000000009900000990
Percentage of StockIssuedDuringPeriodValueDividendReinvestmentPlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockRepurchasedDuringPeriodShares



Period End2020-03-312019-09-302019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-06-302017-03-31
Value20000203340020
Percentage of StockRepurchasedDuringPeriodShares100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareRepurchaseProgram

slg:A2016RepurchaseProgram



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value25201918181515118320
Percentage of StockRepurchasedDuringPeriodShares960.218715.12232.34647.0766.96218.2444.8328.3168.8357.2622.1100.0

us-gaap:StraightLineRent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value-33441661341011111312-53037333232121715111321
Percentage of StraightLineRent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-334416613
Percentage of StraightLineRent100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Ownership

us-gaap:SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest

slg:ServiceCorporation



Period End2020-03-31
Value0.95
Percentage of SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest100.0

us-gaap:Ownership, dei:LegalEntity

slg:SLGManagementLLC, slg:SLGreenManagement



Period End2020-03-31
Value1.0
Percentage of SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest105.3

us-gaap:TreasuryStockAcquiredAverageCostPerShare



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value83.2581.3186.5886.0793.0499.7597.2297.07100.76101.67103.41103.89
Percentage of TreasuryStockAcquiredAverageCostPerShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

us-gaap:TreasuryStockSharesAcquired

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value2000033
Percentage of TreasuryStockSharesAcquired100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value200003340
Percentage of TreasuryStockSharesAcquired100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:TreasuryStockValueAcquiredCostMethod



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2197475342533835449896
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value21974753425338354
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value21974753425338-354
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0100.0100.0100.0100.0-100.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1424946211318619527196
Percentage of TreasuryStockValueAcquiredCostMethod65.066.462.362.653.855.155.154.5100.0

us-gaap:CommonStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value26000.09000.08000.04000.02000.035000.037000.049000.010000.0
Percentage of TreasuryStockValueAcquiredCostMethod0.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value7625281211-151159
Percentage of TreasuryStockValueAcquiredCostMethod35.033.637.737.446.2-44.944.8

us-gaap:ConsolidatedEntities

us-gaap:UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic

srt:Subsidiaries



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value448000.00.0164000.00.033000.055000.042000.0
Percentage of UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic100.00.0100.00.0100.0100.0100.0

us-gaap:UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0-2000000000
Percentage of UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0-20000000
Percentage of UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted100.0100.0100.0100.0100.0-26.2378.8100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:WeightedAverageLimitedPartnershipUnitsOutstanding

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value82-1868787-19091
Percentage of WeightedAverageLimitedPartnershipUnitsOutstanding100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:WeightedAverageLimitedPartnershipUnitsOutstandingDiluted

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value820868787-1909295
Percentage of WeightedAverageLimitedPartnershipUnitsOutstandingDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:EntityCommonStockSharesOutstanding



Period End2020-05-082020-02-272019-11-042019-08-062019-05-082019-02-252018-10-302018-08-072018-05-092018-02-222017-11-072017-08-042017-05-042017-02-172016-11-072016-08-012016-05-062016-02-222015-11-022015-08-032015-05-042015-02-172014-11-032014-07-312014-04-302014-02-142013-10-31
Value767780828484858688909898101100101100100100999999989695959592
Percentage of EntityCommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-05-082020-02-272019-11-042019-05-082019-02-25
Value11111
Percentage of EntityCommonStockSharesOutstanding1.31.31.31.21.2

slg:AccruedInterestPayableAndOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2622272528232726363834363336303636210204161162137127128112114697273731001141161261261021503834
Percentage of AccruedInterestPayableAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value11
Percentage of AccruedInterestPayableAndOther4.25.4

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value262227252823
Percentage of AccruedInterestPayableAndOther100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

srt:Subsidiaries, us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value11
Percentage of AccruedInterestPayableAndOther4.25.4

slg:AccumulatedAmortizationOfDeferredCosts



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
Value274260262260251244236227220217216209207201198191184286273269258251241232220216206195186177167158149141132124114
Percentage of AccumulatedAmortizationOfDeferredCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:AllowanceForDeferredRentsReceivable



Period End2020-03-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1112151515161721232524222321222326272727273029292829303130292829293024
Percentage of AllowanceForDeferredRentsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312018-12-312017-12-31
Value11121517
Percentage of AllowanceForDeferredRentsReceivable100.0100.0100.0100.0

slg:BuildingLeaseholdImprovementsGross



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value143514331431142714231423142714231420145014441441143914371436143514311431142514241423141814051390137513661353135213461346133113161317130212931289152012861280
Percentage of BuildingLeaseholdImprovementsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1435143314311427142314231450
Percentage of BuildingLeaseholdImprovementsGross100.0100.0100.0100.0100.0100.0100.0

slg:DiscountOfStructuredFinanceInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value161416192122162324252415161414141816181819191417181113132223241919194246
Percentage of DiscountOfStructuredFinanceInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value161416192122
Percentage of DiscountOfStructuredFinanceInvestments100.0100.0100.0100.0100.0100.0

us-gaap:CounterpartyName, us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType

slg:DisposalGroupIncludingDiscontinuedOperationOwnershipPercentageinDisposedAsset

slg:NationalPensionServiceOfKoreaAndHinesInterestLP, slg:A1MadisonAve, us-gaap:SubsequentEvent



Period End2020-05-07
Value0.495
Percentage of DisposalGroupIncludingDiscontinuedOperationOwnershipPercentageinDisposedAsset100.0

slg:FinancingReceivableRecordedInOtherAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value12013189878988848988656594909910111911612111511112213313213416117214514112912112011915010878
Percentage of FinancingReceivableRecordedInOtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:CumulativeEffectPeriodOfAdoption

slg:CumulativeEffectPeriodOfAdoptionAdjustment



Period End2020-01-01
Value11
Percentage of FinancingReceivableRecordedInOtherAssets0.0

slg:FiniteLivedIntangibleLiabilitiesAccumulatedAmortization



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
Value246249267258256253251249256402474469470464455498489486476484506483470461446429411391374357346327309290273252220
Percentage of FiniteLivedIntangibleLiabilitiesAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:FiniteLivedIntangibleLiabilitiesGross



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
Value274282304311276276274274359540639643653655648861863866866804847655655676679671667667652651668656649622621534508
Percentage of FiniteLivedIntangibleLiabilitiesGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:FiniteLivedIntangibleLiabilitiesNet



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
Value2732375220222224102137165173182191193362374379390319340171185214233242255275277294322328340331348281287
Percentage of FiniteLivedIntangibleLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:GeneralAndLimitedPartnersCapitalAccount

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5122524755105616557956645984
Percentage of GeneralAndLimitedPartnersCapitalAccount100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

slg:LimitedPartnershipUnitsHeldByGeneralPartner

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value75788081828291
Percentage of LimitedPartnershipUnitsHeldByGeneralPartner100.0100.0100.0100.0100.0100.0100.0

slg:LongTermDebtMaturitiesRepaymentsOfPrincipal



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value6160588961365936562958985456
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipal100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:CreditFacility2012, us-gaap:CorporateJointVenture



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value13003356707901453600
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipal21.15.710.913.32.66.10.0

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1964216324032314199219332270241623242724
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipal31.90.040.837.733.60.040.341.042.60.0

us-gaap:SeniorNotes, us-gaap:CorporateJointVenture



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1250150015001500150014001400
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipal20.325.524.425.326.623.725.7

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4132402839303799381538413949408843334184
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipal67.10.066.761.964.30.070.269.379.40.0

us-gaap:ConsolidatedEntities

slg:MinorityInterestUnitsOfPartnershipOwnedByNoncontrollingOwners

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value4444444
Percentage of MinorityInterestUnitsOfPartnershipOwnedByNoncontrollingOwners100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis

slg:MortgageLoansOnRealEstateFairValueHighEndOfRange

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value1800170021002500250023002200240023002200220018001800160015001500180019002100190018001600170016001400
Percentage of MortgageLoansOnRealEstateFairValueHighEndOfRange100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis

slg:MortgageLoansOnRealEstateFairValueLowEndOfRange

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value1600160019002200230021002000220021002000200016001600150014001400170017001900170015001400150015001300
Percentage of MortgageLoansOnRealEstateFairValueLowEndOfRange100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MortgageLoansOnRealEstateLoanType

slg:MortgageLoansOnRealEstateLoanValue

slg:MezzanineLoanDueMarch2022



Period End2020-03-31
Value400000.0
Percentage of MortgageLoansOnRealEstateLoanValue100.0

slg:MortgageLoansonRealEstateSeniorFinancing



Period End2020-03-312019-12-31
Value61295560
Percentage of MortgageLoansonRealEstateSeniorFinancing100.0100.0

us-gaap:MortgageLoansOnRealEstateLoanType

slg:JuniorMortgage



Period End2020-03-312019-12-31
Value438100
Percentage of MortgageLoansonRealEstateSeniorFinancing7.11.8

slg:MezzanineDebt



Period End2020-03-312019-12-31
Value51695188
Percentage of MortgageLoansonRealEstateSeniorFinancing84.393.3

slg:PreferredEquity



Period End2020-03-312019-12-31
Value522272
Percentage of MortgageLoansonRealEstateSeniorFinancing8.54.9

slg:NetIntangibleAssetsTransferredtoAssetsHeldforSale



Period End2020-03-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value00000013300000242149
Percentage of NetIntangibleAssetsTransferredtoAssetsHeldforSale0.00.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0

slg:NetIntangibleLiabilitiesTransferredtoLiabilitiesRelatedtoAssetsHeldforSale



Period End2020-03-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value000000410000000
Percentage of NetIntangibleLiabilitiesTransferredtoLiabilitiesRelatedtoAssetsHeldforSale0.00.00.00.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, slg:RealEstateByLocation

slg:NumberOfResidentialUnits

slg:ThreeRetailandTwoResidentialUnits, slg:East21Street66



Period End2020-03-312019-09-302019-06-30
Value1.02.02.0
Percentage of NumberOfResidentialUnits100.0100.0100.0

slg:NumberofRealEstateBuildings



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value72.077.077.078.084.090.095.099.0102.0103.0109.0109.0109.0111.0113.0118.0119.0118.0101.099.099.0101.062.0
Percentage of NumberofRealEstateBuildings100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:RealEstateByLocation

slg:Manhattan



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value53.052.052.052.055.056.057.057.058.058.058.058.057.059.059.061.061.061.062.061.062.064.0
Percentage of NumberofRealEstateBuildings73.667.567.566.765.562.260.057.656.956.353.253.252.353.252.251.751.351.761.461.662.663.4

slg:Suburban



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value9.015.015.015.015.021.025.027.029.030.030.030.031.031.032.034.036.036.035.034.034.034.0
Percentage of NumberofRealEstateBuildings12.519.519.519.217.923.326.327.328.429.127.527.528.427.928.328.830.330.534.734.334.333.7

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty

slg:CommercialProperty



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value62.067.067.067.070.077.082.084.087.088.088.088.088.090.091.095.097.097.097.095.096.098.0
Percentage of NumberofRealEstateBuildings86.187.087.085.983.385.686.384.885.385.480.780.780.781.180.580.581.582.296.096.097.097.0

us-gaap:ResidentialRealEstate



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value10.010.010.011.014.013.013.015.015.015.021.021.021.021.022.023.022.021.04.04.03.03.04.0
Percentage of NumberofRealEstateBuildings13.913.013.014.116.714.413.715.214.714.619.319.319.318.919.519.518.517.84.04.03.03.06.5

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, slg:RealEstateByLocation

slg:DevelopmentProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value12.07.07.0
Percentage of NumberofRealEstateBuildings16.79.19.1

slg:OfficeProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value28.030.030.0
Percentage of NumberofRealEstateBuildings38.939.039.0

slg:OfficeProperties, slg:Suburban



Period End2020-03-312019-09-302019-06-30
Value8.013.013.0
Percentage of NumberofRealEstateBuildings11.116.916.9

slg:RetailProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value12.014.014.0
Percentage of NumberofRealEstateBuildings16.718.218.2

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, us-gaap:RealEstateProperties

slg:CommercialProperty, us-gaap:ConsolidatedProperties



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value42.047.048.047.048.054.055.060.062.065.065.065.067.069.069.072.072.072.072.072.072.071.0
Percentage of NumberofRealEstateBuildings58.361.062.360.357.160.057.960.660.863.159.659.661.562.261.161.060.561.071.372.772.770.3

slg:CommercialProperty, us-gaap:UnconsolidatedProperties



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value20.020.019.020.022.023.027.024.025.023.023.023.021.021.022.023.025.025.025.023.024.027.0
Percentage of NumberofRealEstateBuildings27.826.024.725.626.225.628.424.224.522.321.121.119.318.919.519.521.021.224.823.224.226.7

us-gaap:ResidentialRealEstate, us-gaap:ConsolidatedProperties



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value2.02.02.02.04.03.03.03.03.03.03.04.04.04.05.05.05.04.04.04.03.03.0
Percentage of NumberofRealEstateBuildings2.82.62.62.64.83.33.23.02.92.92.83.73.73.64.44.24.23.44.04.03.03.0

us-gaap:ResidentialRealEstate, us-gaap:UnconsolidatedProperties



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value8.08.08.09.010.010.010.012.012.012.018.017.017.017.017.018.017.017.00.00.00.00.0
Percentage of NumberofRealEstateBuildings11.110.410.411.511.911.110.512.111.811.716.515.615.615.315.015.314.314.40.00.00.00.0

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, us-gaap:RealEstateProperties, slg:RealEstateByLocation

slg:DevelopmentProperties, us-gaap:ConsolidatedProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value11.06.06.0
Percentage of NumberofRealEstateBuildings15.37.87.8

slg:OfficeProperties, us-gaap:ConsolidatedProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value18.020.020.0
Percentage of NumberofRealEstateBuildings25.026.026.0

slg:OfficeProperties, us-gaap:ConsolidatedProperties, slg:Suburban



Period End2020-03-312019-09-302019-06-30
Value8.013.013.0
Percentage of NumberofRealEstateBuildings11.116.916.9

slg:RetailProperties, us-gaap:ConsolidatedProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value4.06.07.0
Percentage of NumberofRealEstateBuildings5.67.89.1

slg:RetailProperties, us-gaap:UnconsolidatedProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value8.08.07.0
Percentage of NumberofRealEstateBuildings11.110.49.1

us-gaap:RealEstateProperties

us-gaap:ConsolidatedProperties



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value44.049.050.049.052.057.058.063.065.068.068.069.071.073.074.077.077.076.076.076.075.074.0
Percentage of NumberofRealEstateBuildings61.163.664.962.861.963.361.163.663.766.062.463.365.165.865.565.364.764.475.276.875.873.3

us-gaap:UnconsolidatedProperties



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value28.028.027.029.032.033.037.036.037.035.041.040.038.038.039.041.042.042.025.023.024.027.0
Percentage of NumberofRealEstateBuildings38.936.435.137.238.136.738.936.436.334.037.636.734.934.234.534.735.335.624.823.224.226.7

us-gaap:RealEstateProperties, slg:RealEstateByLocation

us-gaap:ConsolidatedProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value33.032.033.0
Percentage of NumberofRealEstateBuildings45.841.642.9

us-gaap:ConsolidatedProperties, slg:Suburban



Period End2020-03-312019-09-302019-06-30
Value9.015.015.0
Percentage of NumberofRealEstateBuildings12.519.519.5

us-gaap:UnconsolidatedProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value20.020.019.0
Percentage of NumberofRealEstateBuildings27.826.024.7

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

slg:OperatingPartnershipCommonUnitValuePerShareUseForConversion

srt:Subsidiaries, slg:SeriesWPreferredStock



Period End2020-03-31
Value0.0
Percentage of OperatingPartnershipCommonUnitValuePerShareUseForConversion0.0

slg:OtherComprehensiveIncomeLossDeferredNetLossfromTerminatedHedges



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-31
Value0000011223710101111121213131516
Percentage of OtherComprehensiveIncomeLossDeferredNetLossfromTerminatedHedges100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:RealEstateWeightedAverageOccupancy



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value0.9360.9430.9350.9320.930.9290.930.9190.9140.9140.9040.90.9060.9060.9030.8880.9230.9010.9020.8970.8870.8580.870.8670.8950.9250.9190.9170.9160.9170.9140.920.9220.9120.9140.913
Percentage of RealEstateWeightedAverageOccupancy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:RealEstateByLocation

slg:Manhattan



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312011-12-31
Value0.9380.9380.9340.9310.9320.9260.9280.9220.9150.9270.9320.9320.9340.9380.9170.9150.9060.8970.8630.8820.8780.9130.925
Percentage of RealEstateWeightedAverageOccupancy100.2100.3100.2100.1100.2100.8101.5102.0101.7102.3102.9103.2105.2101.6101.8101.4101.0101.1100.6101.4101.3102.0101.4

slg:Suburban



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312011-12-31
Value0.8620.8960.9020.9060.9170.8720.8330.8330.8290.8250.8280.8220.8230.8190.7920.8030.8210.8030.8180.8070.8090.80.862
Percentage of RealEstateWeightedAverageOccupancy92.195.896.897.498.694.991.192.192.191.191.491.092.788.787.989.091.590.595.392.893.389.494.5

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty

slg:CommercialProperty



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.9340.9340.9310.9290.9310.9210.9160.9080.9020.910.9150.9140.9150.920.8980.8980.8910.880.8550.8680.8660.894
Percentage of RealEstateWeightedAverageOccupancy99.899.999.999.9100.1100.2100.2100.4100.2100.4101.0101.2103.099.799.799.699.399.299.799.899.999.9

us-gaap:ResidentialRealEstate



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.9670.950.9450.9330.9240.90.8890.8640.8890.8720.8380.8140.6750.9540.9420.9460.9630.9640.9520.9320.9190.94
Percentage of RealEstateWeightedAverageOccupancy103.3101.6101.4100.399.497.997.395.698.896.292.590.176.0103.4104.6104.9107.4108.7111.0107.1106.0105.0

us-gaap:MortgageLoansOnRealEstateDescriptionTypeOfProperty, slg:RealEstateByLocation

slg:OfficeProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value0.9370.9420.938
Percentage of RealEstateWeightedAverageOccupancy100.1100.7100.6

slg:OfficeProperties, slg:Suburban



Period End2020-03-312019-09-302019-06-30
Value0.8550.8940.9
Percentage of RealEstateWeightedAverageOccupancy91.395.696.6

slg:RetailProperties, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value0.980.9890.989
Percentage of RealEstateWeightedAverageOccupancy104.7105.8106.1

us-gaap:ResidentialRealEstate, slg:Manhattan



Period End2020-03-312019-09-302019-06-30
Value0.9670.950.945
Percentage of RealEstateWeightedAverageOccupancy103.3101.6101.4

us-gaap:RelatedPartyTransactionsByRelatedParty

slg:SecuredDebtAndOtherLoansPayable

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value92029043889686948871905392679544999795486549
Percentage of SecuredDebtAndOtherLoansPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:SecuredDebtBearingFixedInterestAmount



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
Value1129138313851387138813891852186118912400328632993579351835634975599058165824460146094736473246224122413041384340434934573654366234723431335233082935
Percentage of SecuredDebtBearingFixedInterestAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:SecuredDebtBearingVariableInterestAmount



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
Value8808281068979658598531677565465558558657622527633113012051040856750110316061508848729503505466115712571261937942666669464
Percentage of SecuredDebtBearingVariableInterestAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:SecuredDebtDeferredFinanceCostsNet



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
Value2328373628262221222840436966708486110
Percentage of SecuredDebtDeferredFinanceCostsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:SecuredDebtGross



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
Value201022112454236620461988233925382456286538453857423641404024560856716992
Percentage of SecuredDebtGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

slg:SecuredDebtandOtherLoansPayableNet

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value91168951879985918760895091649433987694126453
Percentage of SecuredDebtandOtherLoansPayableNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LongtermDebtType

slg:SeniorNotesNetofDeferredFinanceCosts

slg:SeniorUnsecuredNotes



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
Value124714961496149514951495149413961396139510641086113211281124113011261378
Percentage of SeniorNotesNetofDeferredFinanceCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PlanName

slg:ShareBasedCompensationArrangementbyShareBasedPaymentAwardFungibleUnitsPerShare

slg:StockOptionsStockAppreciationRightsAndOtherAwards



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value0.730.730.730.730.730.730.730.730.730.730.730.730.730.730.730.730.770.770.770.770.770.77
Percentage of ShareBasedCompensationArrangementbyShareBasedPaymentAwardFungibleUnitsPerShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:ThirdAmendmentandRestated2005StockOptionandIncentivePlan



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value3.743.743.743.743.743.743.743.743.743.743.743.742.762.762.762.762.762.76
Percentage of ShareBasedCompensationArrangementbyShareBasedPaymentAwardFungibleUnitsPerShare512.3512.3512.3512.3512.3512.3512.3512.3512.3512.3512.3512.3358.4358.4358.4358.4358.4358.4

slg:VariableInterestEntityNotPrimaryBeneficiaryInvestment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value138145876873869808722680631606598628223220220216181991009897146174185315310136133124117179167164161
Percentage of VariableInterestEntityNotPrimaryBeneficiaryInvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsAndNotesReceivableNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value884344384741444749575450525355575563666450576451476051514148353229323128262722
Percentage of AccountsAndNotesReceivableNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value88434438474157
Percentage of AccountsAndNotesReceivableNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value346371360321321273287308359349232
Percentage of AccountsAndNotesReceivableNet391.5843.9801.8840.4672.6656.8644.4650.0725.3607.1432.9

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value158166143133111147141140131137144134169190178189168196173147151173183164140145167138143159147140137142146130123133125
Percentage of AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value158166143133111147137
Percentage of AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value414642864407445144924508460246014776496852945391565156245596546654515439559355705572528951305085504950154757471646974667458945574469423642254105383636603525
Percentage of AdditionalPaidInCapital100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables



Period End2020-03-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value11121516161818181716181817617151618182020181722202021212019161516131214
Percentage of AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312018-12-312017-12-31
Value11121518
Percentage of AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables100.0100.0100.0100.0

us-gaap:AllowanceForLoanAndLeaseLossesRealEstate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-312009-12-312008-12-31
Value371111500000001477774141504141619398
Percentage of AllowanceForLoanAndLeaseLossesRealEstate100.0100.0100.0100.0100.0100.00.00.00.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value3711115
Percentage of AllowanceForLoanAndLeaseLossesRealEstate100.0100.0100.0100.0100.0100.0

us-gaap:AreaOfRealEstateProperty



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value29272929303030313233313232323233343535343433333334282929292929
Percentage of AreaOfRealEstateProperty100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperation



Period End2020-03-312019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value0391403069659367338127119540117391891341174200462
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperation0.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302018-12-312017-12-31
Value03914030338
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperation0.0100.0100.00.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities



Period End2020-03-312019-12-312019-09-302018-12-31
Value25293028
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FinancialInstrument

us-gaap:FairValueInputsLevel2, us-gaap:CommercialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302018-12-31
Value25293028
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302018-12-31
Value25293028
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:CommercialMortgageBackedSecurities



Period End2020-03-312019-12-312019-09-302018-12-31
Value25293028
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0

us-gaap:BusinessAcquisition

us-gaap:BusinessAcquisitionPercentageOfVotingInterestsAcquired

slg:MadisonAvenue762



Period End2020-01-31
Value0.1
Percentage of BusinessAcquisitionPercentageOfVotingInterestsAcquired100.0

us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets

slg:A126132NassauStreet



Period End2020-01-31
Value0.0
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets0.0

slg:A707EleventhAvenue



Period End2020-01-31
Value90
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets0.0

slg:MadisonAvenue762



Period End2020-01-31
Value29
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets0.0

us-gaap:CollateralAlreadyPostedAggregateFairValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value3000330037003500410039003900380035004800670066007100600064008700890010800105007900790082008000
Percentage of CollateralAlreadyPostedAggregateFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiability



Period End2020-03-312019-12-312019-09-302018-12-31
Value11611412694
Percentage of ContractWithCustomerLiability100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302018-12-31
Value11611412694
Percentage of ContractWithCustomerLiability100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302018-12-31
Value1459150115351660
Percentage of ContractWithCustomerLiability1256.31316.61215.21758.4

us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentCarryingAmount

slg:SeniorUnsecuredNoteDueMarch162020, slg:SeniorUnsecuredNotes



Period End2020-03-31
Value0.0
Percentage of DebtInstrumentCarryingAmount0.0

slg:SeniorUnsecuredNotesDueDecember12022, slg:SeniorUnsecuredNotes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value300300300300300300300300300300200200200200200200200200200200200200200200200200
Percentage of DebtInstrumentCarryingAmount0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LongtermDebtType

slg:SeniorUnsecuredNotes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value12501500150015001500150015001400140014001069109411451145114511551155141013101310131013101310138613861386
Percentage of DebtInstrumentCarryingAmount0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DebtInstrument, us-gaap:SubsequentEventType

us-gaap:DebtInstrumentFaceAmount

slg:FHLBFacilityFebruary2020, us-gaap:SubsequentEvent



Period End2020-02-24
Value15
Percentage of DebtInstrumentFaceAmount100.0

slg:FHLBFacilityJanuary2020, us-gaap:SubsequentEvent



Period End2020-01-31
Value10
Percentage of DebtInstrumentFaceAmount0.0

us-gaap:DeferredCostsCurrentAndNoncurrent



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
Value232205182220211209202198195226247249267267252256246370342328326327310300261267247246252261253249211210191182172
Percentage of DeferredCostsCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value232205182220211209
Percentage of DeferredCostsCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0

us-gaap:DeferredCostsLeasingGross



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
Value506466445481463453438426415443464459475468450447431415405406389385353331324326304292289285274262241238222211200
Percentage of DeferredCostsLeasingGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LongtermDebtType

us-gaap:DeferredFinanceCostsNet

slg:SeniorUnsecuredNotes



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
Value556788978844556677
Percentage of DeferredFinanceCostsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value85919710211110310311012013695
Percentage of DeferredFinanceCostsNet1604.01528.21452.41399.61387.41207.61132.61482.71494.11570.51691.0

us-gaap:DeferredRentReceivablesNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value310283306341337335329322320365393385453442430443428498467433408374364354378386374360355340330315300281265244223201166
Percentage of DeferredRentReceivablesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value310283306341337335365
Percentage of DeferredRentReceivablesNet100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeAsset



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value04251318272623161314162100000002
Percentage of DerivativeFairValueOfDerivativeAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentRisk

slg:InterestRateCapExpiringMarch2021



Period End2020-03-312019-09-302019-06-302019-03-31
Value2000.00.01000.01000.0
Percentage of DerivativeFairValueOfDerivativeAsset100.00.00.00.0

slg:InterestRateSwapExpiringJanuary2024



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-13-6-8-6-3-1
Percentage of DerivativeFairValueOfDerivativeAsset-660100.0-148.7-293.2-121.8-27.0-9.9

slg:InterestRateSwapExpiringJanuary2026



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-19-9-12-9-5-2
Percentage of DerivativeFairValueOfDerivativeAsset-966900.0-211.5-432.8-165.5-37.2-13.1

slg:InterestRateSwapExpiringJanuary20262



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-25-12-16-12-6-3
Percentage of DerivativeFairValueOfDerivativeAsset-1299700.0-285.8-583.7-223.3-50.4-18.0

slg:InterestRateSwapExpiringNovember2020



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value-1000010
Percentage of DerivativeFairValueOfDerivativeAsset-51450.0-6.4-13.3-4.54.25.61.7

slg:InterestRateSwapExpiringNovember20202



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value-1000010
Percentage of DerivativeFairValueOfDerivativeAsset-51650.0-6.5-13.5-4.64.15.51.6

slg:InterestRateSwapExpiringinJuly2023



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312017-09-302017-06-302017-03-31
Value-5313811108-9-10
Percentage of DerivativeFairValueOfDerivativeAsset-267600.068.269.368.061.759.764.465.5-64.4-64.6

slg:InterestRateSwapExpiringinJuly20232



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312017-09-302017-06-302017-03-31
Value-21014554-4-5
Percentage of DerivativeFairValueOfDerivativeAsset-138700.031.830.732.029.929.231.331.6-31.0-31.2

us-gaap:InterestRateContract



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value-68-24-34-23-21116
Percentage of DerivativeFairValueOfDerivativeAsset-3436000.0-558.7-1236.5-419.6-14.759.0100.0

us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel2



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value04251318272623161314162100000002
Percentage of DerivativeFairValueOfDerivativeAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:BalanceSheetLocation

us-gaap:DerivativeFairValueOfDerivativeLiability

slg:AccruedInterestPayableAndOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value68293729157023210
Percentage of DerivativeFairValueOfDerivativeLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel

slg:AccruedInterestPayableAndOther, us-gaap:FairValueInputsLevel2



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value68293729157023210
Percentage of DerivativeFairValueOfDerivativeLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:DerivativeInstrumentRisk, us-gaap:SubsequentEventType

us-gaap:DerivativeFixedInterestRate

slg:SeniorUnsecuredNotesDueAugust2021, us-gaap:InterestRateSwap, us-gaap:SubsequentEvent



Period End2020-04-30
Value0.0054375
Percentage of DerivativeFixedInterestRate100.0

us-gaap:DerivativeInstrumentRisk

slg:InterestRateSwapExpiringJanuary2024



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.026960.026960.026960.026960.0269550.026955
Percentage of DerivativeFixedInterestRate0.00.00.00.00.00.0

us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:DisposalGroupIncludingDiscontinuedOperationConsideration

slg:A315West33rdStreet



Period End2020-03-31
Value446
Percentage of DisposalGroupIncludingDiscontinuedOperationConsideration100.0

us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations, us-gaap:SubsequentEventType

slg:A315West33rdStreet, us-gaap:SubsequentEvent



Period End2020-02-24
Value446
Percentage of DisposalGroupIncludingDiscontinuedOperationConsideration0.0

slg:FifthAvenue609, us-gaap:SubsequentEvent



Period End2020-05-07
Value168
Percentage of DisposalGroupIncludingDiscontinuedOperationConsideration0.0

us-gaap:DividendsPayableCurrentAndNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value267978798080797982858586878781808079676665645353525234343737293029281514141412
Percentage of DividendsPayableCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value26797879808085
Percentage of DividendsPayableCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0

us-gaap:DueFromJointVentures



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
Value1897820181217211516172111211111112221400010001
Percentage of DueFromJointVentures100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DueFromOtherRelatedParties



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
Value711121489810987616141311139910101012717655777763225
Percentage of DueFromOtherRelatedParties100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DueFromRelatedParties



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value262120232928212731232423191514131510111112111381987611777432368
Percentage of DueFromRelatedParties100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value26212023292823
Percentage of DueFromRelatedParties100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

slg:RestrictedStockAwards



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value171516191315181316182113141821781011121416178910115
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeStockOption



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value00011234681012121391212148101214131518208101194
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized0.10.04.67.89.80.027.632.237.00.077.477.668.563.372.183.767.771.0118.9116.1114.3120.5109.7111.3113.1114.0104.7106.3110.582.075.4

us-gaap:PerformanceShares



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-31
Value56312225282579479125610112471076675
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized324.00.0149.0153.6146.90.038.849.353.60.051.859.065.827.144.171.460.29.562.283.999.060.754.047.246.228.1

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:EquityMethodInvestmentSummarizedFinancialInformationAssets

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value1706617096170241688517291172331715417419179291527710712
Percentage of EquityMethodInvestmentSummarizedFinancialInformationAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:EquityMethodInvestmentSummarizedFinancialInformationEquity

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value53045437549155445668567556655643564744683510
Percentage of EquityMethodInvestmentSummarizedFinancialInformationEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:EquityMethodInvestmentSummarizedFinancialInformationLiabilitiesAndEquity

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value1706617096170241688517291172331715417419179291527710712
Percentage of EquityMethodInvestmentSummarizedFinancialInformationLiabilitiesAndEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value28482912292329373055301930703059303423622045221918611890186011261146120312391262124411729969711061111311091085107310321020101410228939218969166311058
Percentage of EquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value2848291229232937305530192362
Percentage of EquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value2800291229002900305530193070305930342362
Percentage of EquityMethodInvestments98.3100.099.298.7100.0100.0100.0100.0100.0100.0

us-gaap:FinanceLeaseLiability



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1624444444343
Percentage of FinanceLeaseLiability100.0100.0100.0100.0100.0100.0

slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value5757
Percentage of FinanceLeaseLiability35.7129.8

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1624444444343
Percentage of FinanceLeaseLiability100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

srt:Subsidiaries, us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value5757
Percentage of FinanceLeaseLiability35.7129.8

us-gaap:FinanceLeaseRightOfUseAsset



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1634747474747
Percentage of FinanceLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1634747474747
Percentage of FinanceLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0

us-gaap:MortgageLoansOnRealEstateLoanType

us-gaap:FinancingReceivableAllowanceForCreditLosses

slg:DebtInvestmentsInMortgageLoans



Period End2020-03-312019-12-31
Value220
Percentage of FinancingReceivableAllowanceForCreditLosses100.00.0

slg:PreferredEquityInvestmentsInMortgageLoans



Period End2020-03-312019-12-31
Value151
Percentage of FinancingReceivableAllowanceForCreditLosses70.00.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization



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
Value202228248247244241239239241277398403416410397420407403392399408383371382364343325296279263252233214193177157133
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsGross



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
Value22525527828226626626126328232547448964865162410221022939939941968664674702779746732732725725744733721673690567758
Percentage of FiniteLivedIntangibleAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:GeneralPartnersCapitalAccountUnitsOutstanding

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value807000.0834000.0858000.0867000.0875000.0878000.0973000.0
Percentage of GeneralPartnersCapitalAccountUnitsOutstanding100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentBuildingAndBuildingImprovements



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value54175154535257495294526852715225520663517468747679777948777793629334104231007983978697877886798843776778847440739374527389743873107191714767316835575458405585
Percentage of InvestmentBuildingAndBuildingImprovements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value501481
Percentage of InvestmentBuildingAndBuildingImprovements9.39.3

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5417515453525749529452686351
Percentage of InvestmentBuildingAndBuildingImprovements100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

srt:Subsidiaries, us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value501481
Percentage of InvestmentBuildingAndBuildingImprovements9.39.3

us-gaap:MortgageLoansOnRealEstateLoanType, us-gaap:Range, us-gaap:InvestmentType

us-gaap:InvestmentInterestRate

slg:MezzanineDebt, srt:Maximum, slg:FixedRate



Period End2020-03-312019-12-31
Value0.0950.1
Percentage of InvestmentInterestRate100.0100.0

slg:PreferredEquity, srt:Minimum, slg:FixedRate



Period End2020-03-312019-12-31
Value0.0650.07
Percentage of InvestmentInterestRate68.470.0

slg:SeniorMortgage, srt:Maximum, slg:FixedRate



Period End2020-03-31
Value0.06
Percentage of InvestmentInterestRate63.2

slg:SeniorMortgage, srt:Minimum, slg:FixedRate



Period End2020-03-31
Value0.03
Percentage of InvestmentInterestRate31.6

us-gaap:InvestmentType

us-gaap:InvestmentOwnedUnderlyingFaceAmountAtMarketValue

slg:DebtInvestmentWithFloatingInterestRate



Period End2020-03-312019-12-31
Value839622
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue100.0100.0

slg:FixedRate



Period End2020-03-312019-12-31
Value998974
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue118.9156.6

us-gaap:MortgageLoansOnRealEstateLoanType, us-gaap:InvestmentType

slg:JuniorMortgage, slg:DebtInvestmentWithFloatingInterestRate



Period End2020-03-312019-12-31
Value9032
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue10.85.1

slg:MezzanineDebt, slg:DebtInvestmentWithFloatingInterestRate



Period End2020-03-312019-12-31
Value375247
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue44.739.8

slg:MezzanineDebt, slg:FixedRate



Period End2020-03-312019-12-31
Value509728
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue60.7117.0

slg:PreferredEquity, slg:FixedRate



Period End2020-03-312019-12-31
Value386244
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue46.139.4

slg:SeniorMortgage, slg:DebtInvestmentWithFloatingInterestRate



Period End2020-03-312019-12-31
Value374342
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue44.655.1

slg:SeniorMortgage, slg:FixedRate



Period End2020-03-312019-12-31
Value1011
Percentage of InvestmentOwnedUnderlyingFaceAmountAtMarketValue12.10.2

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation



Period End2020-03-312019-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value00031126504100065016122901780266
Percentage of LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation0.00.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312018-12-312017-12-31
Value0004
Percentage of LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation0.00.00.0100.0

us-gaap:ConsolidatedEntities

us-gaap:LimitedPartnersCapitalAccount

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value358409401401412387461
Percentage of LimitedPartnersCapitalAccount100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:LimitedPartnersCapitalAccountUnitsOutstanding

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value4444444
Percentage of LimitedPartnersCapitalAccountUnitsOutstanding100.0100.0100.0100.0100.0100.0100.0

us-gaap:LineOfCredit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value12942343286637824921363510302751950027776699494970552038524400220340403070200804003505005005006501374
Percentage of LineOfCredit100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value129423432866378249230
Percentage of LineOfCredit100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument

slg:UncommittedMasterRepurchaseAgreement2017



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value13715218928129929929929918990
Percentage of LineOfCredit10.665.157.742.438.360.9219.085.20.0297.0

us-gaap:RevolvingCreditFacility



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-312013-09-302013-06-302013-03-312012-12-31
Value1300240335670790500145360028020000285775994949705520385244220340403070
Percentage of LineOfCredit100.4102.6102.0101.0100.9101.6106.0102.50.0101.5102.50.00.0102.7101.1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument

us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity

slg:TermLoan



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-07-312015-06-302015-03-312014-12-312014-11-302014-06-302014-03-312012-11-30
Value150015001500150015001500150012001200120012001200933933933933933833833833833783783400
Percentage of LineOfCreditFacilityMaximumBorrowingCapacity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:UncommittedMasterRepurchaseAgreement2017



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-04-302018-03-312017-06-30
Value300300300300300300300400300300
Percentage of LineOfCreditFacilityMaximumBorrowingCapacity20.00.020.020.020.020.020.00.020.025.0

us-gaap:StatementGeographical, us-gaap:CreditFacility

slg:A410TenthAvenue, us-gaap:ConstructionLoans



Period End2020-03-312019-12-31
Value4650
Percentage of LineOfCreditFacilityMaximumBorrowingCapacity31.00.0

us-gaap:MortgageLoansOnRealEstateLoanType, us-gaap:Range, us-gaap:InvestmentType, us-gaap:VariableRate

us-gaap:LoansReceivableBasisSpreadOnVariableRate

slg:MezzanineDebt, srt:Maximum, slg:DebtInvestmentWithFloatingInterestRate, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-312019-12-31
Value0.15290.1236
Percentage of LoansReceivableBasisSpreadOnVariableRate100.0100.0

slg:MezzanineDebt, srt:Minimum, slg:DebtInvestmentWithFloatingInterestRate, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-312019-12-31
Value0.04950.046
Percentage of LoansReceivableBasisSpreadOnVariableRate32.437.2

slg:SeniorMortgage, srt:Minimum, slg:DebtInvestmentWithFloatingInterestRate, us-gaap:LondonInterbankOfferedRateLIBOR



Period End2020-03-312019-12-31
Value0.020.0275
Percentage of LoansReceivableBasisSpreadOnVariableRate13.122.2

us-gaap:FairValueByMeasurementBasis

us-gaap:LongTermDebtFairValue

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-31
Value616255545892614059405591563359025460591064766431665665576505806310063104341013083758089843287366919
Percentage of LongTermDebtFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-31
Value624256616026624260315288566559485514603467136591694268326936850410412107701062688318698888191647214
Percentage of LongTermDebtFairValue101.3101.9102.3101.7101.594.6100.6100.8101.0102.1103.7102.5104.3104.2106.6105.5103.5103.2104.9105.4107.5105.3104.9104.3

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value816106615451545154515453113321228563396
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:CreditFacility2012, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value000000145360040
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive0.00.00.00.00.00.04.711.20.01.2

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value61386311361136113611361251113611401639
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive75.180.973.573.573.573.540.235.439.948.3

slg:TermLoan, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value002002002002001500150015001500
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive0.00.012.912.912.912.948.246.752.544.2

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1934181318312431243024302879287928782119
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive236.9170.1118.5157.3157.3157.392.589.6100.862.4

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value47847816922092221219221007100710071008
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:CreditFacility2012, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value003356707905000000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive0.00.019.832.035.726.00.00.00.00.0

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value27227250115115115198198198198
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive57.057.03.05.55.26.019.719.719.719.7

slg:TermLoan, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value20020013001300130013000000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive41.841.876.862.158.767.60.00.00.00.0

us-gaap:SeniorNotes, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value000000800800800800
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive0.00.00.00.00.00.079.479.479.479.4

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value61717311277277277220220220223
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive128.93.618.413.312.614.521.921.921.922.2

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value265715971546130710071008361111111
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:CreditFacility2012, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value130024000000000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour48.915.00.00.00.00.00.00.00.00.0

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value50507374981981980000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour1.93.147.738.119.719.70.00.00.00.0

slg:TermLoan, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1300130000000000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour48.981.40.00.00.00.00.00.00.00.0

us-gaap:SeniorNotes, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value00800800800800350000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour0.00.051.761.279.479.496.80.00.00.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value311311268220220220454454454449
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour11.719.517.416.921.921.9125.73906.33905.93858.4

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1550133859659055150197712521142953
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value741529234229189139704979869679
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree47.839.539.438.834.427.972.078.276.171.3

us-gaap:SeniorNotes, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value800800350350350350250250250250
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree51.659.858.759.263.569.825.620.021.926.2

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value268268704604522518276276471473
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree17.320.1118.0102.394.7103.428.322.041.349.7

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value5936014915685865761581448442
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value231239230307325315116102420
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo39.139.946.954.155.554.773.370.749.90.0

us-gaap:SeniorNotes, us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value3503502502502502500000
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo59.058.250.844.042.643.40.00.00.00.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value884805804251251278115252262717
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo149.1133.9163.544.342.948.372.8175.2310.91697.1

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear



Period End2020-03-312019-09-302019-06-302019-03-31
Value63163132
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear100.0100.0100.0100.0

us-gaap:DebtInstrument, us-gaap:RelatedPartyTransactionsByRelatedParty

slg:MortgageAndOtherLoansPayable, us-gaap:CorporateJointVenture



Period End2020-03-312019-09-302019-06-302019-03-31
Value55142727
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear86.886.388.084.2

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-09-302019-06-302019-03-31
Value1141013112
Percentage of LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear181.363.744.2344.2

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

us-gaap:LongtermDebtPercentageBearingFixedInterestAmount

us-gaap:FairValueInputsLevel3, us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value311736423661363036273230351637963840442153985359580457225922705875077591761064196582656565366533595358865334
Percentage of LongtermDebtPercentageBearingFixedInterestAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value303235363538354035423543350637653795430551545190551654525494661271547232713760116016614061336096559355994922
Percentage of LongtermDebtPercentageBearingFixedInterestAmount97.397.196.697.597.7109.799.799.298.897.495.596.895.195.392.893.795.395.393.893.691.493.593.893.394.095.192.3

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementBasis

us-gaap:LongtermDebtPercentageBearingVariableInterestAmount

us-gaap:FairValueInputsLevel3, us-gaap:EstimateOfFairValueFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value312520182364261224042057214921511673161213141232113811101014144529053179301524122116231526272279161313271557
Percentage of LongtermDebtPercentageBearingVariableInterestAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value313020182353259923982048212621371665160513211241114011051010145129083202299223642073229126032261160113191597
Percentage of LongtermDebtPercentageBearingVariableInterestAmount100.2100.099.599.599.799.598.999.399.599.6100.6100.7100.299.699.7100.4100.1100.799.298.098.099.099.199.299.399.4102.6

us-gaap:MarketableSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value252930292928282828282829298560394345464647393939323232262221212325255455643458
Percentage of MarketableSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value25293029292828
Percentage of MarketableSecurities100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:MinorityInterestInOperatingPartnerships

srt:PartnershipInterest



Period End2020-03-312019-12-312018-12-312017-12-312016-12-31
Value358409387461473
Percentage of MinorityInterestInOperatingPartnerships100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:StatementClassOfStock

us-gaap:MinorityInterestInPreferredUnitHolders

srt:Subsidiaries, us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value266283286286285300301
Percentage of MinorityInterestInPreferredUnitHolders100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:Ownership

us-gaap:MinorityInterestOwnershipPercentageByNoncontrollingOwners

srt:Subsidiaries, slg:OperatingPartnership



Period End2020-03-312019-12-31
Value0.05140.0503
Percentage of MinorityInterestOwnershipPercentageByNoncontrollingOwners100.0100.0

us-gaap:MortgageLoansOnRealEstate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312015-12-31
Value1783158019542228227220991977216820852114202016401670
Percentage of MortgageLoansOnRealEstate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MortgageLoansOnRealEstateCommercialAndConsumerNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1783158019542228227220991977216820852114202019861627164014531357137816701501168515481408143215471493130413151227144313571071982999985897582579963784
Percentage of MortgageLoansOnRealEstateCommercialAndConsumerNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MortgageLoansOnRealEstateLoanType

us-gaap:NotesReceivableNet

slg:PreferredEquityInvestmentsInMortgageLoans



Period End2020-03-312019-12-31
Value367239
Percentage of NotesReceivableNet100.0100.0

us-gaap:OperatingLeaseLiability



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value3633813843873893
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value3633813843873893
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value902897898900901637
Percentage of OperatingLeaseLiability247.9235.1233.7232.4231.317684.4

us-gaap:OtherAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value35333227123532429530129036031039536058461462097910558509121144978647729679815750729699722718774784796737753575693819290
Percentage of OtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value179169
Percentage of OtherAssets50.750.9

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value353332271235324295310
Percentage of OtherAssets100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

srt:Subsidiaries, us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value179169
Percentage of OtherAssets50.750.9

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value1997203920842093219121872235225423611407683
Percentage of OtherAssets564.8612.8767.8889.5675.1739.7742.3775.6654.9453.1111.3

us-gaap:OtherLiabilities



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
Value2141771401231351169710810318895195162206211243247168
Percentage of OtherLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value4543
Percentage of OtherLiabilities21.324.7

us-gaap:ConsolidatedEntities

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value214177140123135116188
Percentage of OtherLiabilities100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, slg:InvestmentsByConsolidatedAndNonconsolidatedEntities

srt:Subsidiaries, us-gaap:VariableInterestEntityPrimaryBeneficiary



Period End2020-03-312019-12-31
Value4543
Percentage of OtherLiabilities21.324.7

us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:CorporateJointVenture



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value284308300290341946474478493411391
Percentage of OtherLiabilities132.3174.1213.3234.0251.9811.8486.0442.8476.0218.6189.8

us-gaap:OtherMinorityInterests



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value807571694646525149364366411440426429428426431433408394521518492491491488488488487488489490477384392519518524
Percentage of OtherMinorityInterests100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:PartnersCapital

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value5263544156925809579759016225
Percentage of PartnersCapital100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

us-gaap:PartnersCapitalAccountUnits

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value7679818283838583899210099
Percentage of PartnersCapitalAccountUnits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:PartnersCapitalAttributableToNoncontrollingInterest

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value807571694646364
Percentage of PartnersCapitalAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities

us-gaap:PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest

srt:Subsidiaries



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value534355175763587958445947626758446537658977507719
Percentage of PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConsolidatedEntities, us-gaap:PartnerCapitalComponents, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:GeneralPartner, us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value512252475510561655795664595655796237598470807074
Percentage of PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest95.995.195.695.595.595.295.095.595.490.891.391.6

us-gaap:ConsolidatedEntities, us-gaap:StatementEquityComponents

srt:Subsidiaries, us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value-80-28-40-28-41536-4281822-8
Percentage of PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest-1.5-0.5-0.7-0.5-0.10.30.6-0.10.40.30.3-0.1

srt:Subsidiaries, us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value807571694646524649364426431
Percentage of PartnersCapitalIncludingPortionAttributableToNoncontrollingInterest1.51.41.21.20.80.80.80.80.85.55.55.6

us-gaap:ConsolidatedEntities, us-gaap:StatementCl