BIIB


Line plots across dimensions of each concept
Tables

Table of contents



us-gaap:CommonStockValue
us-gaap:StatementEquityComponents
us-gaap:SharesIssued

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:Revenues
us-gaap:MajorCustomers, us-gaap:ProductOrService
us-gaap:MajorCustomers, us-gaap:TypeOfArrangement
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:StatementGeographical
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, us-gaap:TypeOfArrangement

us-gaap:RealizedInvestmentGainsLosses

us-gaap:CostOfRevenue

us-gaap:CostOfGoodsAndServicesSold

us-gaap:SellingGeneralAndAdministrativeExpense

us-gaap:InterestExpense
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:OperatingExpenses

us-gaap:CostsAndExpenses
us-gaap:TypeOfArrangement
us-gaap:ResearchAndDevelopmentExpense

us-gaap:SellingGeneralAndAdministrativeExpense

us-gaap:OperatingIncomeLoss

us-gaap:InterestExpense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax

us-gaap:NonoperatingIncomeExpense
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:IncomeTaxExpenseBenefit
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ProfitLoss

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:NetIncomeLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome
us-gaap:StatementEquityComponents

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents

us-gaap:Assets

us-gaap:Liabilities

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity

us-gaap:AssetsCurrent

us-gaap:AccountsReceivableNetCurrent

us-gaap:InventoryNet

us-gaap:OtherAssetsCurrent

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsNet
us-gaap:ProductOrService, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:OtherAssetsNoncurrent

us-gaap:LiabilitiesCurrent

us-gaap:NotesPayableCurrent

us-gaap:AccountsPayableCurrent

us-gaap:OtherAccruedLiabilitiesCurrent

us-gaap:TaxesPayableCurrent

us-gaap:OtherLiabilitiesCurrent

us-gaap:LongTermDebt

us-gaap:MinorityInterest
us-gaap:StatementEquityComponents

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:StockholdersEquity

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapital

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValue

us-gaap:MinorityInterest
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome
us-gaap:StatementEquityComponents

us-gaap:ProfitLoss

us-gaap:DepreciationDepletionAndAmortization

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:IncreaseDecreaseInInventories

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:PaymentsForRepurchaseOfCommonStock
us-gaap:ShareRepurchaseProgram
us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:ShareBasedCompensation

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

biib:AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears
us-gaap:ValuationAllowancesAndReservesType
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
biib:Biogenshareofcopromotionprofitsorlosses

biib:Collaborationprofitlosssharing
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:TypeOfArrangement
biib:ContractOptionExerciseFee

biib:CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear
us-gaap:ValuationAllowancesAndReservesType
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
biib:Derivativesusedinnetinvestmenthedgenetoftaxexcludedcomponentincreasedecrease

biib:EffectiveTaxRateReconciliationGILTItax
us-gaap:MajorCustomers
biib:EntityWidePercentageOfRevenueFromMajorDistributors
us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement
biib:ExpenseIncurredByCollaboration
us-gaap:TypeOfArrangement
us-gaap:ProductOrService, us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement
biib:Expenseincurredbythecollaboration
us-gaap:ProductOrService, us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement
biib:Expensereflectedwithinstatementsofincome
us-gaap:TypeOfArrangement
us-gaap:MajorCustomers
biib:OtherrevenuesfromantiCD20therapeuticprograms

biib:PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear
us-gaap:ValuationAllowancesAndReservesType

biib:PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear
us-gaap:ValuationAllowancesAndReservesType
us-gaap:TypeOfArrangement
biib:PercentageoffuturedevelopmentcostsrelatedtoEisai

biib:ShareBasedCompensationExpenseIncludedInCostsAndExpenses
us-gaap:MajorCustomers
biib:ShareOfCoPromotionProfits

us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:AwardType
us-gaap:IncomeStatementLocation
us-gaap:StatementEquityComponents

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax

us-gaap:AmortizationOfIntangibleAssets

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:DebtSecuritiesAvailableForSaleRealizedGain

us-gaap:DebtSecuritiesAvailableForSaleRealizedLoss

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:Depreciation
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation
us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation
us-gaap:DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DiscontinuedOperationTaxEffectOfDiscontinuedOperation

us-gaap:DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown

us-gaap:EffectOfExchangeRateOnCashAndCashEquivalents

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate

us-gaap:EffectiveIncomeTaxRateReconciliationDispositionOfAssets

us-gaap:EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential

us-gaap:EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepreciationAndAmortization

us-gaap:EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther

us-gaap:EffectiveIncomeTaxRateReconciliationOtherAdjustments

us-gaap:EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCredits

us-gaap:EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense

us-gaap:EquitySecuritiesFvNiGainLoss

us-gaap:EquitySecuritiesFvNiRealizedGainLoss

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax

us-gaap:GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments

us-gaap:IncomeLossFromEquityMethodInvestments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions

us-gaap:IncomeLossFromIndividuallySignificantComponentDisposedOfOrHeldForSaleExcludingDiscontinuedOperationsAttributableToParentBeforeIncomeTax

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInAccruedIncomeTaxesPayable

us-gaap:IncreaseDecreaseInAccruedLiabilities

us-gaap:IncreaseDecreaseInDueFromRelatedParties

us-gaap:IncreaseDecreaseInEquitySecuritiesFvNi
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities
us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InvestmentIncomeInterest

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax

us-gaap:OtherNoncashIncomeExpense

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireInProcessResearchAndDevelopment

us-gaap:PaymentsToAcquireIntangibleAssets

us-gaap:PaymentsToAcquireOtherProductiveAssets

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesEquity

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
us-gaap:StatementEquityComponents

us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost

us-gaap:ResearchAndDevelopmentInProcess
us-gaap:BusinessAcquisition

us-gaap:RestructuringCharges
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesTreasuryStockReissued

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueTreasuryStockReissued
us-gaap:StatementEquityComponents
us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents
us-gaap:StockRepurchasedAndRetiredDuringPeriodShares

us-gaap:StockholdersEquityOther
us-gaap:StatementEquityComponents

us-gaap:TranslationAdjustmentForNetInvestmentHedgeNetOfTaxPeriodIncreaseDecrease
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:ShareRepurchaseProgram
us-gaap:TreasuryStockRetiredCostMethodAmount
us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents
us-gaap:ShareRepurchaseProgram
us-gaap:TreasuryStockSharesAcquired
us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents
us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType
us-gaap:ShareRepurchaseProgram
us-gaap:TreasuryStockValueAcquiredCostMethod
us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:UnrealizedGainLossOnForeignCurrencyDerivativesNetBeforeTax

us-gaap:WeightedAverageNumberDilutedSharesOutstandingAdjustment

biib:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveYearsAmortizedCost

biib:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveYearsFairValue

biib:Collaborationexpensesaccrual

biib:DuefromantiCD20therapeuticprograms
us-gaap:BusinessAcquisition
biib:EstimatedAdditionalPaymentsUponAchievementOfDevelopmentAndCommercialMilestones
us-gaap:TypeOfArrangement

biib:Inventorynetcurrentandnoncurrent

biib:InvestmentInBiotechnologyCompaniesThatAreDeterminedToBeUnconsolidatedVariableInterestEntities
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
biib:PlanAssetsForDeferredCompensationFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency
us-gaap:FinancialInstrument
biib:StrategicInvestmentPortfolio

biib:UnrealizedGainLossesOnForeignCurrencyDerivativesNetBeforeTax
biib:DerivativeMaturity
us-gaap:TypeOfArrangement
biib:UpfrontAndMilestonePaymentsMadeToCollaborativePartner

us-gaap:AccruedIncomeTaxesNoncurrent

us-gaap:AccruedRoyaltiesCurrent
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentAfterTax
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecurities
us-gaap:FinancialInstrument
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesAmortizedCost

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue

us-gaap:AvailableForSaleSecuritiesDebtSecurities
us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesNoncurrent
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:BusinessCombinationContingentConsiderationLiability
us-gaap:FairValueByMeasurementFrequency

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent
us-gaap:Range, us-gaap:MeasurementInputType
us-gaap:BusinessCombinationContingentConsiderationLiabilityMeasurementInput

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency

us-gaap:CashEquivalentsAtCarryingValue
us-gaap:InvestmentType
biib:FacilityLocation
us-gaap:ConstructionInProgressGross

us-gaap:ConstructionPayableCurrentAndNoncurrent

us-gaap:DebtInstrumentFairValue

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxLiabilitiesNet
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeFairValueOfDerivativeAsset
us-gaap:BalanceSheetLocation, us-gaap:HedgingDesignation
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeFairValueOfDerivativeLiability
us-gaap:BalanceSheetLocation, us-gaap:HedgingDesignation
us-gaap:Currency, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeNotionalAmount
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:HedgingDesignation
us-gaap:TypeOfArrangement
us-gaap:DueFromRelatedParties
us-gaap:TypeOfArrangement
us-gaap:DueToRelatedPartiesCurrentAndNoncurrent

us-gaap:EmployeeRelatedLiabilitiesCurrent
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquityMethodInvestmentOwnershipPercentage
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquityMethodInvestments

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsGross
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:ForeignCurrencyContractAssetFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:ForeignCurrencyContractsLiabilityFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency
us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass
us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill
us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass, biib:Researchanddevelopmentasset

us-gaap:IntangibleAssetsGrossExcludingGoodwill

us-gaap:InventoryFinishedGoodsNetOfReserves

us-gaap:InventoryRawMaterialsNetOfReserves

us-gaap:InventoryWorkInProcessNetOfReserves
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:InvestmentsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:LiabilitiesFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency

us-gaap:NotesPayable
us-gaap:DebtInstrument
us-gaap:DebtInstrument
us-gaap:NotesPayableFairValueDisclosure

us-gaap:OperatingLeaseLiabilityNoncurrent
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:PurchaseCommitmentRemainingMinimumAmountCommitted

us-gaap:ValuationAllowancesAndReservesBalance
us-gaap:BalanceSheetLocation
us-gaap:ValuationAllowancesAndReservesType

Tables

  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:CommonStockValue ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▇█████████████████▇▇100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0124000.0129000.0129000.0129000.0129000.0128000.0128000.0128000.0128000.0128000.0128000.0127000.0127000.0127000.0129000.0128000.0128000.0127000.0125000.0124000.0NANANA144000.0NANANA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents us-gaap:CommonStock▁▂▃▄▅▆▆▃██191198205208219221225201234235NANANA238NANANA241NANANA257NANANA255NANANA254NANANA0NANANA248NANANA288NANANA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents us-gaap:PreferredStock▄▄▄▄▄▄▄▄▄▄0000000000NANANA0NANANA0NANANA0NANANA0NANANA0NANANA0NANANA0NANANA0NANANA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents us-gaap:TreasuryStock▄▄▄▄▄▄▄▄▄▄23232323232323232323NANANA22NANANA22NANANA22NANANA-19NANANA-17NANANA0NANANA-7NANANA-13NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding ▁▂▂▃▄▄▄▅▅▅▅▅▆▆▆▆▆▆▇██████173178184190197200201207211212211212215217219219219220232235235236236237237NA238238238NA238240241NA245244244NA242261272NANANANA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic ▁▂▂▃▄▄▄▅▅▅▅▅▆▆▆▆▆▆███████172177184190196199201207211211211211215216218219218220232235234235236236236NA237237236NA236238239NA242242241NA239259269NANANANA
us-gaap:EarningsPerShareBasic ████▇▅▇▅▆▁▆▅▄▄▅▅▅▅▅▅▅▅▅▄▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▂▃8.18.18.47.857.174.747.174.185.55-1.415.84.073.473.04.724.794.443.774.163.943.53.753.633.022.031.942.062.071.81.241.681.621.261.241.451.191.221.01.061.130.81.070.960.490.85
us-gaap:EarningsPerShareDiluted ████▇▅▇▅▆▁▆▅▄▄▅▅▅▅▅▅▄▅▅▄▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▃▂▃8.088.088.397.857.154.737.154.185.54-1.45.794.073.462.994.714.794.433.774.153.933.493.743.623.012.021.922.052.061.791.231.671.611.251.221.431.181.20.991.051.120.81.060.950.490.84
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:Revenues ██████▇▇▇▇▆▆▆▆▆▆▅▆▆▅▅▅▅▅▄▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁353436713600361634893526343933563131330730773078281028722955289427262839277725912554264025112421212919651827172314151417138514201292132613091208120312191175121211081127112010931036
 us-gaap:Revenues us-gaap:ProductOrService biib:Interferon▁▃▃▄▂▅▅▆▄▇▇█▇466516530554500597590625550644662690648NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService biib:MSProductRevenues▅▇▇█▁█▇█▂211721822160220419832194217222022025NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService biib:Revenuesfromanticd20therapeuticprograms▆██▇▆▆▆▅▄▃▃▃▁520600595576517534511490443415406397340NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService biib:SPINRAZA███▇▇▇▇▆▅▅▄▃▁56554354748851846946742236336227020247NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService biib:Tecfidera▆█▇█▂▆▆▅▂▅▅▆▁1100116111221150998111010901086986107510691110958NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService biib:TysabriProduct▆▂▃▂▁▁▂▂▁▁▂▄█522472483475460464470467462462469496545NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService us-gaap:Product███▇▅▇▆▆▃▅▄▄▁2904292428942880268028252780275725232712262226392380NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService,us-gaap:StatementGeographical biib:MSProductRevenues,country:US▃▇▆▇▁█▇█▃134715111465151312901544151615361350NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService,us-gaap:StatementGeographical biib:MSProductRevenues,us-gaap:NonUs█▂▄▃▄▁▁▂▂769670694690693650656666675NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService,us-gaap:StatementGeographical biib:Tecfidera,country:US▄█▆█▁▇▆▆▁▆▆█▂777877842869717856842825728831836875751NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService,us-gaap:StatementGeographical us-gaap:Product,country:US▂▆▅▆▁▆▆▆▂▆▆█158317541702174415131780174017411538175117741860NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:Revenues us-gaap:ProductOrService,us-gaap:StatementGeographical us-gaap:Product,us-gaap:NonUs█▅▅▄▅▂▂▂▁13211170119211351166104510391015985NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RealizedInvestmentGainsLosses -77NA-4-173376NA1415-14NA-4-13NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:CostOfRevenue ▄▃▃▄█▅▄▃▃▅▁▁454447430476602488460421446509370366NANANANANANANANANANANANANANANANA133NA1391391331391231001031009510697NANANANA
us-gaap:CostOfGoodsAndServicesSold ▄▃▃▄█▅▄▃▃▅▁▁454447430476602488460421446509370366NANANANANANANANANANANANANANANANA133NA1391391331391231001031009510697NANANANA
us-gaap:SellingGeneralAndAdministrativeExpense ▅█▅▆▅▆▃▄▃▅▁▁▃▃▂▃▃▆▂▃▅▅▅▅▃570664554587567591497516501572433430499495462492497583477491560573570576511NA405431352NA299301300283261266244276244262248NANANANA
us-gaap:InterestExpense ▅▆▆▆▆▆▆▆▆▇▇███████▂▁▁▁▁▁▁44464547474949515062616363646665636715567777NA6711NA87777899998NANANANA
 us-gaap:OperatingExpenses us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedGainLossNetCashFlowHedgeParent▁█▁▁▁▁▁▁█▁▁▁010000001000NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:CostsAndExpenses ▄▆▅▄▇▇▄█▃▅▂▆▅▇▃▂▁▄▂▁▂▂▁▂▂1714189317931660198720831741214315961841142418771786198515301433134816711406135814371485136314361462NA11501066909NA882915922917821797787863981816805NANANANA
 us-gaap:ResearchAndDevelopmentExpense us-gaap:TypeOfArrangement biib:SangamoTherapeuticsInc.AgreementNANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:SellingGeneralAndAdministrativeExpense ▅█▅▆▅▆▃▄▃▅▁▁▃▃▂▃▃▆▂▃▅▅▅▅▃570664554587567591497516501572433430499495462492497583477491560573570576511NA405431352NA299301300283261266244276244262248NANANANA
us-gaap:OperatingIncomeLoss ▇▇▇█▆▅▇▄▆▅▆▄▃▂▅▅▅▄▅▄▃▄▄▃▁1819177718061955150214431697121315341465165312001024886142514601378116813711233111711591152988671NA684662510NA535505369409488410416355194395303NANANANA
us-gaap:InterestExpense ▅▆▆▆▆▆▆▆▆▇▇███████▂▁▁▁▁▁▁44464547474949515062616363646665636715567777NA6711NA87777899998NANANANA
us-gaap:OtherNonoperatingIncomeExpense █▇███████████▁███▄██▇█▇██-4-36-3-70-1-3-3-1-4-5-52-203-4-5-4-116-2-8-14-8-164-5NA-4-10-14NA-4215-3-7-119-4-61-869146
us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax ▂▇█▄▄▄▅▁▇▅▆█▆▂▄▃▅▄▄▇▁▃▃▅▅-635279-10-17-298-924412438220-75-14-589-35-2363-100-37-60-8-2NA338-24NA25-5125NA-5022NANANANANANANANANA
us-gaap:NonoperatingIncomeExpense ▂▃▃▁█▃▅▃▃▃▃▃▃▃▃▃▃▂▃▃▃-120-49-27-197357-28115-34-41-66-43-68-37-48-58-58-52-82-15-10-15NA-164NANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NonoperatingIncomeExpense us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedGainLossNetCashFlowHedgeParent▄▄▄▄▄▄▄▄▄▄▄▄000000000000NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NonoperatingIncomeExpense us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest▁▁███▄▁▁▁002221000NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:IncomeTaxExpenseBenefit ▂▁▁▁▂▂▂▁▂█▂▁▁▁▂▂▂▁▂▂▂▁▁▁▁2922762112484224693692633221566383269239190337353356257330292281268274268178NA18615965NA1311218210412795117787510275NANANANA
us-gaap:ProfitLoss ▇███▇▆█▅▆▁▇▅▅▄▆▆▆▅▆▅▅▅▅▅▄▄▄▄▃▃▃▃▃▃▃▃▃▃▂▃▃▃▃▂▃1392143915451494140894414429151171-1661226862747647103010489698281019924820882856723479457487490426292398387302300353304308271112294220306279144246
us-gaap:ComprehensiveIncomeNetOfTax ▇▇█▇▇▅▇▅▆▁▆▅▅▄▆▆▅▅▅▅▅▅▅▄▄1385139617061461142995414579081185-286123584974263010141026935764909896811861845710485NA513503414NA397354311NA334333332NANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest ▅▅▅▅▅█▅▄▅▁▅▅▅▅▅▅▅▅▃▅▅▅▅▅▅-50000881-481-13100012112-532200-80NA000NA000NA11817NANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▇▇█▇▇▅▇▅▆▁▆▅▄▄▅▅▅▄▅▅▅▅▅▄▃1379139617061460142995214569571184-155123584974262810121024933762962894809861844718485NA513503414NA397353311266334333332258136239189NANANANA
us-gaap:NetIncomeLoss ▇███▇▆█▅▇▁▇▅▅▅▆▆▆▅▆▆▅▅▅▅▄▄▄▄▄▃▄▄▃▃▃▃▃▃▃▃▃▃▃▃▃1399143915451494140894614448661172-297122686274764910321049970831965927822883856714479457487490426292398386302300351288294240254293217305277142244
 us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:RetainedEarnings▆▇█▇▇▂▇▁▄1399143915451494140894614448661172NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▁▁▁▁▁▁▁▄▁█▁▁▁▁▁▁▁▁▄▁▁▁▁▂▁-60000-1-148-1131000-1-2-1-1-253-2-20080NA000NA00001161431-141120122
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:Assets █████▇▇▇▇▇▆▆▆▆▆▆▆▅▆▄▄▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁26119272342748426287264452528825492239522609023652230732175921195228762210421514206741950420728167591521914316137041291712230118631125010841101641013096309162911390498802862182938092NANANA8551NANANA
us-gaap:Liabilities ████▇▇▇▇▇▆▆▆▅▆▆▆▆▆▆▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁1358213895134921333812623122571173211699120521105410224101859728107489990101111034610129101614186354935023273335230893242312429392825316629682891280526222568256526192643NANANA2289NANANA
us-gaap:LiabilitiesAndStockholdersEquity █████▇▇▇▇▇▆▆▆▆▆▆▆▅▆▄▄▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁26119272342748426287264452528825492239522609023652230732175921195228762210421514206741950420728167591521914316137041291712230118631125010841101641013096309162911390498802862182938092NANANA8551NANANA
us-gaap:StockholdersEquity ▇▇█▇█▇█▇█▇▇▆▆▆▆▆▅▄▅▇▆▅▅▄▄▄▃▃▃▂▂▂▂▂▂▁▁▁125461334313995129521382913039137661226014053126121286011585114791214012117114031032693721057212572116661080910427956191368620812579017339696166596268630564256229597756045396NANANA6221NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:AssetsCurrent ▆▆▆▆▇▆▇▅█▆▆▅▅▇▆▅▅▅▇▄▃▃▃▂▂▂▁▁▄▂▁▁▁▁▁▁▁▁800783818448790989427640871974321019578737568710868598732809174477201670092705618525846724372392535253184264325235328324430552868267729752837268826282540NANANA2480NANANA
us-gaap:AccountsReceivableNetCurrent █▇▇▇█▇█▇▇▇▆▆▅▅▅▄▅▄▄▄▅▄▃▃▃▂▂▂▂▁▁▁▁▁▁▁▁▁2092188019331959208819582017195119391787156716301501144114671293139512271327131013891292109110021018824891861753686661683684584581666687605NANANA551NANANA
us-gaap:InventoryNet ▆▆▅▆▆▇▇▇▇▇█▇▇████▇▇▇▆▆▅▅▅▅▄▄▃▂▂▂▁▁▁▁858804751776770929916931890902100793692110011009996964893918865825804753715672659614570506447392362337326310308NA289NANANANANANANA
us-gaap:OtherAssetsCurrent ▅▄▅▆▆▅▆▆▆▆▆▇█▇▆▇▆▆▆▅▄▃▃▂▂▂▂▁▁▁▁▁▁▁▁▁▁▂6836317439809656878488438959629671146123110939931027941836861750579447396346295226205173169136126149122144194201186215NANANA177NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment ▇▇▇████▇▇▇▇▇▇▇▇▇▇▇▇▆▆▆▆▆▆▆▆▆▆▆▁▅▅▅▅▅▅▅1636159015551886184117971730167116311559158015111438143915281471139413301320127412171186124612101163111810741030983941-898854821782749771789767NANANA642NANANA
us-gaap:PropertyPlantAndEquipmentNet ▇▇▆▆▆██▇▇▇▆▅▅▄▄▄▃▃▃▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁32813247313830773013360135383409333431822995282726102501238723012258218720271837173917651724175617441750180617871736174216761622161715711572171216731641NANANA1637NANANA
us-gaap:Goodwill ███████▇▇▆▆▅▅▅▄▄▄▃▃▃▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁57525757574657495639570654405170490746324127387036113669341931672917266324082154184917601541136412321232121012101210120112041197119311461146114611461146NANANA1138NANANA
us-gaap:IntangibleAssetsNetExcludingGoodwill ▅▅▅▆▄▄▅▆▆▆▇▇▇▆▆▆▆▇▇▇▇▇▇▇▇███▁▁▁▁▁▁▁▁▁▁34463527339236813056312033793661379438794019405141033808386939674012408541814294435340284129424943644474458046781581163116811732178316081659167817311772NANANA1871NANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass biib:OutLicensedPatents██▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▂▂▂▂2426249700011357101316192328323743495561697785127134142149157164171179186196207NA227NANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:ProductOrService,us-gaap:FiniteLivedIntangibleAssetsByMajorClass biib:AVONEX,us-gaap:DevelopedTechnologyRights154NA236246256265275285NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:ProductOrService,us-gaap:FiniteLivedIntangibleAssetsByMajorClass biib:TysabriProduct,biib:InLicensedPatents1800NA188919331980202720732120NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ▅▅▅▆█▇▄▄▂▄▆▅▅▆▅▅▅▅▄▃▃▃▂▃▃▃▃▂▁▁▁▁▂▁▁▁▁▁1130125212381306189816901009902380102713001268118413351239115310941107892751640618565611639594636533306274271271368331237211228248NANANA230NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:LiabilitiesCurrent ██▇▅▅▅▅▅▅▅▆▅▅▅▄▄▄▄▄▄▃▃▃▃▂▃▂▂▂▂▂▂▂▁▁▁▁▁4638486344323210314832953174315231523368344833792992341924992516277625772633255519462219194019161594175815181304128116571521143213379128859549781050NANANA714NANANA
us-gaap:NotesPayableCurrent █▁▁150114951495NANA0NANANANANANANANANANANANANANANANANANANANANANA20345345345345333131134137NANANA19NANANA
us-gaap:AccountsPayableCurrent ▅█▅▅▅▅▄▄▅▅▄▄▄▃▃▂▃▃▃▃▂▂▂▂▂▂▁▁▁▂▁▁▁▂▁▁▁▁389530382377378370342295345395298330316279274225271267251282236229233224212219166163165203157159173186159170159162NANANA118NANANA
us-gaap:OtherAccruedLiabilitiesCurrent ▇█▇██▆▇▇▇▇▆▆▄▇▆▆▆▆▅▄▃▄▁▁662726677727708609640638653636606591475685566613582579549433403456276263NA285NANANANANANANANANANANANANANANANANANANA
us-gaap:TaxesPayableCurrent ▅▂▃▇▄▂▅▄▄▂▃▂▂▄▄▄█▄▇▇▅▃▃▄▃▃▃▂▁▁▁▂▂▂▂▁▂▂31071125427238632542232316812152702312082124962084584573221681591921611791448128204458504547109384NANANA75NANANA
us-gaap:OtherLiabilitiesCurrent ▇█▇▆▇█▇▇▇█▇▇▅█▅▅▅▆▅▅▃▅▄▄▃▃▃▂▂▂▂▂▁▁▁▁▁▁2437276524292318243528612578263325712901245524362044290320122072200320961918181213841819154414951216135512041056885979866762660677674641591665NANANA500NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:LongTermDebt ▆▆▆▇▇▇▇▇▇▇▇▇▇██████▁▁▁▁▁▁▁▁▁4459445944585948594359365931592859295935593859545952651265296538653565216529576580582583586591592694726NA687NANANANANANANANANANANANANANANA
us-gaap:MinorityInterest ▁▂▂▂▂▂▂▂▁▁▁▁▁▁▂▂▂▂▂▂▂▃▂▂▂▂▂▂▂▂▂▂▂▂▂█▇▆▅▅▅▅-10-4-4-4-7-8-6-7-16-14-11-11-11-11-2012-5025334000022221479705239404140NANANA
us-gaap:OtherLiabilitiesNoncurrent ▆▆▇▆▆▇▇▇██▃▃▃▃▄▄▄▄▄▄▄▃▃▃▃▃▃▂▃▂▂▂▂▁▁▁▁▁1357134813701355135313891511145716401628716750688722862951916905861915892650658710702659608595674604539534517400384351356325NANANA254NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:StockholdersEquity ▇▇█▇█▇█▇█▇▇▆▆▆▆▆▅▄▅▇▆▅▅▄▄▄▃▃▃▂▂▂▂▂▂▁▁▁125461334313995129521382913039137661226014053126121286011585114791214012117114031032693721057212572116661080910427956191368620812579017339696166596268630564256229597756045396NANANA6221NANANA
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest ▇▇█▇█▇█▇█▇▇▆▆▆▆▆▅▄▅▇▆▅▅▄▄▄▃▃▃▂▂▂▂▂▂▁▁▁125361333913991129481382213031137591225314037125981284811573114671212812114114031032893741056612572116691081410430956591418620812579027339696366616270630864266233605656745449NANANA6261NANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:RetainedEarnings▂▅▇▄▇▄▇▁█▂15673164551706516182170261625716944154991733415810NANANA15071NANANA12208NANANA9283NANANA6349NANANA4486NANANA3106NANANA1872NANANA1068NANANA
us-gaap:CommonStockValue ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▇█████████████████▇▇100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0124000.0129000.0129000.0129000.0129000.0128000.0128000.0128000.0128000.0128000.0128000.0127000.0127000.0127000.0129000.0128000.0128000.0127000.0125000.0124000.0NANANA144000.0NANANA
us-gaap:AdditionalPaidInCapital ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▃████████▇▇▇▇▇█████▇00000047009759190006918013424251424241964150410640544023398739173858385438193825421741854143422439753895NANANA5781NANANA
us-gaap:RetainedEarningsAccumulatedDeficit ▇██▇███▇█▇▇▇▇▇▇▇▆▆▆▅▅▄▄▄▃▃▃▃▂▂▂▂▂▂▁▁▁▁15673164551706516182170261625716944154991733415810161071488114781150711503014229131791220811999110331010692838400754368296349589154044913448641943796340931062806245421661872NANANA1068NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▅▅▆▃▃▃▃▂▂▁▁▁▁▁▂▂▃▃▄▆▆▆▇▇▇▇▇▆▆▆▇▇▇▇███▇-149-135-92-252-219-240-248-261-303-318-329-338-325-319-300-282-259-224-157-101-70-59-37-26-22-27-29-55-67-55-51-50-17-267250-21NANANA50NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedGainLossNetCashFlowHedgeParent▇▆█▆▇▇▆▆▁▂▂▃4177213513440-133-104-104-69NA57NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss▃▅▆▆▅▃▄▄▄▄▃▃▁▂▄▆▄▄▄▄▄▄▄▄▆▅█▆▅▅-34662-4-1-1-2-1-4-5-12-100610-1000007515934NANANA0NANANA12NANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest█▄█▅▃▁▁▁▁▁482550291730000NANANA0NANANA0NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:TreasuryStockValue █████████████▇▇▇▇▇▇▇▇▇▆▆▅▅▅▄▄▄▄▄▄▂▂▂▂▁297729772977297729772977297729772977297729772977297726112611261126112611261126112611261120842061172417241724136513651324130313031303839728728537349NANANA679NANANA
us-gaap:MinorityInterest ▁▂▂▂▂▂▂▂▁▁▁▁▁▁▂▂▂▂▂▂▂▃▂▂▂▂▂▂▂▂▂▂▂▂▂█▇▆▅▅▅▅-10-4-4-4-7-8-6-7-16-14-11-11-11-11-2012-5025334000022221479705239404140NANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▆█▇█▆█▇▅▆▆▇▅▁▇▄▄▄▅▄▅▃▄▄▄▁146719601694196414591895173510991457151816281169235157698699596310408951047733932914990104NANANA178NANA635194473570429253431428428336NANANANA
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▇▄▅▆▁▄▂█▃▂▅▃▄▅▃▂▁▃▂▄▄▄▄▅442708-365-110238-1625-619-11481346-769-1246-202-744-58136-736-1203-1807-989-1253-502-378-540-6305NANANA155NANA-530-389-587-546-126-518-69683249NANANANA
us-gaap:NetCashProvidedByUsedInFinancingActivities ▂▂▄▂▄▃▄▁▄▄▄▄▃▄▄▄▄▂█▄▅▄▄▄▅-2245-2116-689-2375-679-143725-2791-268-708-19-751-901-721-300-1347-19982907-380-513-35-322114NANANA-238NANA-417-416-142-9921-99225-461-1026-523NANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▆█▇█▆█▇▅▆▆▇▅▁▇▄▄▄▅▄▅▃▄▄▄▁146719601694196414591895173510991457151816281169235157698699596310408951047733932914990104NANANA178NANA635194473570429253431428428336NANANANA
us-gaap:NetIncomeLoss ▇███▇▆█▅▇▁▇▅▅▅▆▆▆▅▆▆▅▅▅▅▄▄▄▄▄▃▄▄▃▃▃▃▃▃▃▃▃▃▃▃▃1399143915451494140894614448661172-297122686274764910321049970831965927822883856714479457487490426292398386302300351288294240254293217305277142244
 us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:RetainedEarnings▆▇█▇▇▂▇▁▄1399143915451494140894614448661172NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▇███▇▆█▅▆▁▇▅▅▄▆▆▆▅▆▅▅▅▅▅▄▄▄▄▃▃▃▃▃▃▃▃▃▃▂▃▃▃▃▂▃1392143915451494140894414429151171-1661226862747647103010489698281019924820882856723479457487490426292398387302300353304308271112294220306279144246
us-gaap:DepreciationDepletionAndAmortization ▁▁▅▁▂▅▅▂▂▁▂▅█▂▃▂▂▂▂▂▂▂▂▂▃11911332911712132934617116889177302512177180175149156151144147157175164190NANANA97NANANANANANANANANANANANANANANANA
us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet ▃▃▃▁█▁▆▃▄▃▅█▄▅▃▂▃▁▅▃▅▅▂▃▅-182-19-90171-8689-2820-18621533448-12-35-14-9055-36953-66-3175NANANA-35NANA5020NANA75-6NANANANANANANANA
us-gaap:IncreaseDecreaseInInventories ▇▇▇▆▁▆▅▇▅▃█▆▇▅▆▆█▆▇▇▆▇▇▇▆62666120-12920-842-2-75853946102639882469592166475516NANANA60NANANA192311186205-9-12NANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▇▄▅▆▁▄▂█▃▂▅▃▄▅▃▂▁▃▂▄▄▄▄▅442708-365-110238-1625-619-11481346-769-1246-202-744-58136-736-1203-1807-989-1253-502-378-540-6305NANANA155NANA-530-389-587-546-126-518-69683249NANANANA
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▅▃▂▆▄█▅▆▇██▇▇▆▆▄▄▆█▄▃▃▁▁▁1491109018612722516318619423022919721018217013612618622912997106626454NANANA33NANA72547051543248384738NANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▂▂▄▂▄▃▄▁▄▄▄▄▃▄▄▄▄▂█▄▅▄▄▄▅-2245-2116-689-2375-679-143725-2791-268-708-19-751-901-721-300-1347-19982907-380-513-35-322114NANANA-238NANA-417-416-142-9921-99225-461-1026-523NANANANA
us-gaap:PaymentsForRepurchaseOfCommonStock ▆▆▃▇▃▄▁█▂▁▁▃▂▃▂▁▁▆█222020937172401655135202750250007815836513480020012955NANA526233360NA-359NA41NANA446463111019119504681031577NANANANA
 us-gaap:PaymentsForRepurchaseOfCommonStock us-gaap:ShareRepurchaseProgram biib:December2019ShareRepurchaseProgram941NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PaymentsForRepurchaseOfCommonStock us-gaap:ShareRepurchaseProgram biib:March2019ShareRepurchaseProgram1300NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31

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
Value100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0124000.0129000.0129000.0129000.0129000.0128000.0128000.0128000.0128000.0128000.0128000.0127000.0127000.0127000.0129000.0128000.0128000.0127000.0125000.0124000.0144000.0
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 Issued

us-gaap:StatementEquityComponents

us-gaap:SharesIssued

us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value1911982052082192212252012342352382412572552540248288297295
Percentage of SharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PreferredStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value00000000000000000000
Percentage of SharesIssued0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value23232323232323232323222222-19-170-7-13-90
Percentage of SharesIssued12.512.011.611.410.910.810.611.810.110.19.59.48.8-7.7-6.9-5.3-3.1-4.7-3.10.0

Common Stock Shares Issued

Common Stock Shares Outstanding

Common Stock Shares Authorized

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value173178184190197200201207211212211212215217219219219220232235235236236237237238238238238240241245244244242261272
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value172177184190196199201207211211211211215216218219218220232235234235236236236237237236236238239242242241239259269
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value8.18.18.47.857.174.747.174.185.55-1.415.84.073.473.04.724.794.443.774.163.943.53.753.633.022.031.942.062.071.81.241.681.621.261.241.451.191.221.01.061.130.81.070.960.490.85
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value8.088.088.397.857.154.737.154.185.54-1.45.794.073.462.994.714.794.433.774.153.933.493.743.623.012.021.922.052.061.791.231.671.611.251.221.431.181.20.991.051.120.81.060.950.490.84
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value353436713600361634893526343933563131330730773078281028722955289427262839277725912554264025112421212919651827172314151417138514201292132613091208120312191175121211081127112010931036
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MajorCustomers, us-gaap:ProductOrService

biib:Bioverativ, us-gaap:ProductAndServiceOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value20676653420675364747
Percentage of Revenues5.92.11.81.05.92.11.11.41.5
Percentage of Revenues5.92.11.81.05.92.11.11.41.5
Percentage of Revenues biib:Bioverativ us-gaap:ProductAndServiceOther100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MajorCustomers, us-gaap:TypeOfArrangement

biib:SamsungBiosimilarAgreement, us-gaap:CollaborativeArrangement



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value316125224154814178912
Percentage of Revenues0.10.40.41.40.70.41.40.40.60.30.30.4
Percentage of Revenues0.10.40.41.40.70.41.40.40.60.30.30.4
Percentage of Revenues biib:SamsungBiosimilarAgreement us-gaap:CollaborativeArrangement100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:ZINBRYTA, us-gaap:CollaborativeArrangement



Period End2020-03-312019-03-31
Value00
Percentage of Revenues0.0-0.0
Percentage of Revenues0.0-0.0
Percentage of Revenues biib:ZINBRYTA us-gaap:CollaborativeArrangement100.0100.0

us-gaap:ProductOrService

biib:BENEPALI



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value133126115120124125123115120117998865
Percentage of Revenues3.83.43.23.33.63.63.63.43.93.63.22.92.3
Percentage of Revenues3.83.43.23.33.63.63.63.43.93.63.22.92.3
Percentage of Revenues biib:BENEPALI100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Biosimilars



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value218195183184174156134126127
Percentage of Revenues6.25.35.15.15.04.43.93.84.1
Percentage of Revenues6.25.35.15.15.04.43.93.84.1
Percentage of Revenues biib:Biosimilars100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:FAMPYRA



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value28252424222222232424242220
Percentage of Revenues0.80.70.70.70.70.60.70.70.80.70.80.70.7
Percentage of Revenues0.80.70.70.70.70.60.70.70.80.70.80.70.7
Percentage of Revenues biib:FAMPYRA100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:FLIXABI



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value231818161414111164210
Percentage of Revenues0.70.50.50.50.40.40.30.30.20.10.10.10.0
Percentage of Revenues0.70.50.50.50.40.40.30.30.20.10.10.10.0
Percentage of Revenues biib:FLIXABI100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:FUMADERM



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value333345457810109
Percentage of Revenues0.10.10.10.10.10.10.10.20.20.30.30.30.3
Percentage of Revenues0.10.10.10.10.10.10.10.20.20.30.30.30.3
Percentage of Revenues biib:FUMADERM100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:IMRALDI



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value615149473516000
Percentage of Revenues1.71.41.41.31.00.50.00.00.0
Percentage of Revenues1.71.41.41.31.00.50.00.00.0
Percentage of Revenues biib:IMRALDI100.0100.0100.0100.0100.0100.00.00.00.0

biib:Interferon



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value466516530554500597590625550644662690648
Percentage of Revenues13.214.114.715.314.416.917.218.617.619.521.522.423.1
Percentage of Revenues13.214.114.715.314.416.917.218.617.619.521.522.423.1
Percentage of Revenues biib:Interferon100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:MSProductRevenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value211721822160220419832194217222022025
Percentage of Revenues59.959.460.060.956.862.263.265.664.7
Percentage of Revenues59.959.460.060.956.862.263.265.664.7
Percentage of Revenues biib:MSProductRevenues100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Othercorporaterevenues



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value941229310526414791791401433020
Percentage of Revenues2.73.32.62.97.64.22.72.44.54.41.00.7
Percentage of Revenues2.73.32.62.97.64.22.72.44.54.41.00.7
Percentage of Revenues biib:Othercorporaterevenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Revenuesfromanticd20therapeuticprograms



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value520600595576517534511490443415406397340
Percentage of Revenues14.716.416.515.914.815.214.914.614.212.513.212.912.1
Percentage of Revenues14.716.416.515.914.815.214.914.614.212.513.212.912.1
Percentage of Revenues biib:Revenuesfromanticd20therapeuticprograms100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:SPINRAZA



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value56554354748851846946742236336227020247
Percentage of Revenues16.014.815.213.514.913.313.612.611.611.08.86.61.7
Percentage of Revenues16.014.815.213.514.913.313.612.611.611.08.86.61.7
Percentage of Revenues biib:SPINRAZA100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Tecfidera



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1100116111221150998111010901086986107510691110958
Percentage of Revenues31.131.631.231.828.631.531.732.431.532.534.836.134.1
Percentage of Revenues31.131.631.231.828.631.531.732.431.532.534.836.134.1
Percentage of Revenues biib:Tecfidera100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:TysabriProduct



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value522472483475460464470467462462469496545
Percentage of Revenues14.812.913.413.113.213.213.713.914.814.015.316.119.4
Percentage of Revenues14.812.913.413.113.213.213.713.914.814.015.316.119.4
Percentage of Revenues biib:TysabriProduct100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Product



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2904292428942880268028252780275725232712262226392380
Percentage of Revenues82.279.780.479.676.880.180.882.280.682.085.285.784.7
Percentage of Revenues82.279.780.479.676.880.180.882.280.682.085.285.784.7
Percentage of Revenues us-gaap:Product100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductAndServiceOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value109145109160292165147108164179484190
Percentage of Revenues3.14.03.04.48.44.74.33.25.35.41.61.43.2
Percentage of Revenues3.14.03.04.48.44.74.33.25.35.41.61.43.2
Percentage of Revenues us-gaap:ProductAndServiceOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Royalty



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value117323271710201111
Percentage of Revenues0.30.20.10.10.10.10.20.50.30.60.40.4
Percentage of Revenues0.30.20.10.10.10.10.20.50.30.60.40.4
Percentage of Revenues us-gaap:Royalty100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProductOrService, us-gaap:StatementGeographical

biib:BENEPALI, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value133126115120124125123115120
Percentage of Revenues3.83.43.23.33.63.63.63.43.9
Percentage of Revenues3.83.43.23.33.63.63.63.43.9
Percentage of Revenues biib:BENEPALI us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Biosimilars, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value218195183184174156134126127
Percentage of Revenues6.25.35.15.15.04.43.93.84.1
Percentage of Revenues6.25.35.15.15.04.43.93.84.1
Percentage of Revenues biib:Biosimilars us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:FAMPYRA, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value282524242222222324
Percentage of Revenues0.80.70.70.70.70.60.70.70.8
Percentage of Revenues0.80.70.70.70.70.60.70.70.8
Percentage of Revenues biib:FAMPYRA us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:FLIXABI, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value23181816141411116
Percentage of Revenues0.70.50.50.50.40.40.30.30.2
Percentage of Revenues0.70.50.50.50.40.40.30.30.2
Percentage of Revenues biib:FLIXABI us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:FUMADERM, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value333345457
Percentage of Revenues0.10.10.10.10.10.10.10.20.2
Percentage of Revenues0.10.10.10.10.10.10.10.20.2
Percentage of Revenues biib:FUMADERM us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:IMRALDI, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value615149473516000
Percentage of Revenues1.71.41.41.31.00.50.00.00.0
Percentage of Revenues1.71.41.41.31.00.50.00.00.0
Percentage of Revenues biib:IMRALDI us-gaap:NonUs100.0100.0100.0100.0100.0100.00.00.00.0

biib:Interferon, country:US



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value292359360379327430421444371449473501464
Percentage of Revenues8.39.810.010.59.412.212.313.211.913.615.416.316.5
Percentage of Revenues8.39.810.010.59.412.212.313.211.913.615.416.316.5
Percentage of Revenues biib:Interferon country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Interferon, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value173157169174173166168180178
Percentage of Revenues4.94.34.74.85.04.74.95.45.7
Percentage of Revenues4.94.34.74.85.04.74.95.45.7
Percentage of Revenues biib:Interferon us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:MSProductRevenues, country:US



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value134715111465151312901544151615361350
Percentage of Revenues38.141.240.741.937.043.844.145.843.1
Percentage of Revenues38.141.240.741.937.043.844.145.843.1
Percentage of Revenues biib:MSProductRevenues country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:MSProductRevenues, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value769670694690693650656666675
Percentage of Revenues21.818.319.319.119.918.519.119.921.6
Percentage of Revenues21.818.319.319.119.918.519.119.921.6
Percentage of Revenues biib:MSProductRevenues us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:SPINRAZA, country:US



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value23524223623022323622320518821819719446
Percentage of Revenues6.76.66.66.46.46.76.56.16.06.66.46.31.7
Percentage of Revenues6.76.66.66.46.46.76.56.16.06.66.46.31.7
Percentage of Revenues biib:SPINRAZA country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:SPINRAZA, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value329300310257295233243216175
Percentage of Revenues9.38.28.67.18.56.67.16.55.6
Percentage of Revenues9.38.28.67.18.56.67.16.55.6
Percentage of Revenues biib:SPINRAZA us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Tecfidera, country:US



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value777877842869717856842825728831836875751
Percentage of Revenues22.023.923.424.020.624.324.524.623.325.127.228.426.7
Percentage of Revenues22.023.923.424.020.624.324.524.623.325.127.228.426.7
Percentage of Revenues biib:Tecfidera country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Tecfidera, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value323284280280281254247261258
Percentage of Revenues9.17.77.87.88.17.27.27.88.2
Percentage of Revenues9.17.77.87.88.17.27.27.88.2
Percentage of Revenues biib:Tecfidera us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:TysabriProduct, country:US



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value277269263264245256253265249252266289305
Percentage of Revenues7.97.37.37.37.07.37.47.98.07.68.79.410.9
Percentage of Revenues7.97.37.37.37.07.37.47.98.07.68.79.410.9
Percentage of Revenues biib:TysabriProduct country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:TysabriProduct, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value244203220211215207217201212
Percentage of Revenues6.95.56.15.86.25.96.36.06.8
Percentage of Revenues6.95.56.15.86.25.96.36.06.8
Percentage of Revenues biib:TysabriProduct us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Product, country:US



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value158317541702174415131780174017411538175117741860
Percentage of Revenues44.847.847.348.243.450.550.651.949.153.057.660.5
Percentage of Revenues44.847.847.348.243.450.550.651.949.153.057.660.5
Percentage of Revenues us-gaap:Product country:US100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Product, us-gaap:NonUs



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value13211170119211351166104510391015985
Percentage of Revenues37.431.933.131.433.429.630.230.331.5
Percentage of Revenues37.431.933.131.433.429.630.230.331.5
Percentage of Revenues us-gaap:Product us-gaap:NonUs100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value2738352914-98103217183
Percentage of Revenues0.81.11.00.80.4-0.30.20.31.10.50.60.1
Percentage of Revenues0.81.11.00.80.4-0.30.20.31.10.50.60.1
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossNetCashFlowHedgeParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, us-gaap:TypeOfArrangement

biib:SamsungBiosimilarAgreement, us-gaap:CollaborativeArrangement



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value31252241548141719812
Percentage of Revenues0.10.41.40.70.41.40.40.60.60.30.4
Percentage of Revenues0.10.41.40.70.41.40.40.60.60.30.4
Percentage of Revenues biib:SamsungBiosimilarAgreement us-gaap:CollaborativeArrangement100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Sales Revenue Goods Net

Realized Investment Gains Losses

us-gaap:RealizedInvestmentGainsLosses



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value-77-4-1733761415-14-4-13
Percentage of RealizedInvestmentGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-2.2-0.1-4.810.84.10.2-0.5-0.1-0.4

Cost Of Revenue

us-gaap:CostOfRevenue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4544474304766024884604214465093703661331391391331391231001031009510697
Percentage of CostOfRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.912.211.913.217.313.913.412.514.215.412.011.99.510.19.810.310.59.48.38.68.28.28.88.8

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value4544474304766024884604214465093703661331391391331391231001031009510697
Percentage of CostOfGoodsAndServicesSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.912.211.913.217.313.913.412.514.215.412.011.99.510.19.810.310.59.48.38.68.28.28.88.8

Cost Of Goods Sold

Selling General And Administrative Expense

us-gaap:SellingGeneralAndAdministrativeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value570664554587567591497516501572433430499495462492497583477491560573570576511405431352299301300283261266244276244262248
Percentage of SellingGeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues16.118.115.416.216.316.814.515.416.017.314.114.017.817.315.717.018.220.517.219.021.921.722.723.824.022.225.024.921.621.223.221.420.022.020.322.720.821.622.4

Interest Expense

us-gaap:InterestExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value44464547474949515062616363646665636715567777671187777899998
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues1.31.31.31.31.41.41.41.51.61.92.02.12.32.32.22.32.32.40.60.20.30.30.30.30.40.40.40.80.60.50.60.60.60.70.80.80.80.70.7

Gross Profit

Operating Expenses

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:OperatingExpenses

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value010000001000
Percentage of OperatingExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues0.00.00.00.00.0-0.00.00.00.0-0.00.00.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossNetCashFlowHedgeParent0.43.42.32.33.44.33.63.84.0-0.62.710.0

Costs And Expenses

us-gaap:CostsAndExpenses



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value171418931793166019872083174121431596184114241877178619851530143313481671140613581437148513631436146211501066909882915922917821797787863981816805
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues48.551.649.845.956.959.150.663.951.055.746.361.063.669.151.849.549.458.950.652.456.256.354.359.368.762.961.964.363.764.471.469.262.766.065.470.983.567.472.6

Research And Development Expense

us-gaap:TypeOfArrangement

us-gaap:ResearchAndDevelopmentExpense

biib:SangamoTherapeuticsInc.Agreement



Period End2020-02-29
Value85
Percentage of ResearchAndDevelopmentExpense100.0
Percentage of Revenues0.0
Percentage of Revenues biib:SangamoTherapeuticsInc.Agreement0.0

Selling General And Administrative Expense

us-gaap:SellingGeneralAndAdministrativeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value570664554587567591497516501572433430499495462492497583477491560573570576511405431352299301300283261266244276244262248
Percentage of SellingGeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues16.118.115.416.216.316.814.515.416.017.314.114.017.817.315.717.018.220.517.219.021.921.722.723.824.022.225.024.921.621.223.221.420.022.020.322.720.821.622.4

Litigation Settlement Expense

Operating Income Loss

us-gaap:OperatingIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1819177718061955150214431697121315341465165312001024886142514601378116813711233111711591152988671684662510535505369409488410416355194395303
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues51.548.450.254.143.140.949.436.149.044.353.739.036.430.948.250.550.641.149.447.643.843.945.940.831.537.538.436.138.635.628.630.837.334.034.629.116.532.627.4

Interest Expense

us-gaap:InterestExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value44464547474949515062616363646665636715567777671187777899998
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues1.31.31.31.31.41.41.41.51.61.92.02.12.32.32.22.32.32.40.60.20.30.30.30.30.40.40.40.80.60.50.60.60.60.70.80.80.80.70.7

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-4-36-3-70-1-3-3-1-4-5-52-203-4-5-4-116-2-8-14-8-164-5-4-10-14-4215-3-7-119-4-61-869146
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.1-1.0-0.1-0.2-0.0-0.0-0.1-0.1-0.1-0.1-0.2-0.20.1-7.1-0.1-0.2-0.2-4.1-0.1-0.3-0.6-0.3-0.60.2-0.3-0.3-0.6-1.0-0.30.21.2-0.3-0.6-1.00.8-0.4-0.60.1-0.80.60.81.30.7

Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-30
Value-635279-10-17-298-924412438220-75-14-589-35-2363-100-37-60-8-2338-2425-5125-5022
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-1.81.42.2-0.3-0.5-0.80.2-2.71.40.41.42.70.7-2.6-0.5-2.00.4-1.2-0.82.4-3.9-1.4-2.4-0.3-0.11.80.5-1.71.8-3.61.9-3.91.8

Income Loss From Continuing Operations Before Income Taxes Domestic

Income Loss From Continuing Operations Before Income Taxes Foreign

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-09-302014-06-30
Value-120-49-27-197357-28115-34-41-66-43-68-37-48-58-58-52-82-15-10-15-164
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-3.4-1.3-0.8-5.510.2-0.83.3-1.0-1.3-2.0-1.4-2.2-1.3-1.7-2.0-2.0-1.9-2.9-0.6-0.4-0.6-0.60.2

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value000000000000
Percentage of NonoperatingIncomeExpense-0.1-0.2-0.4-0.00.0-0.30.1-0.0-0.2-0.2-0.2-0.0
Percentage of Revenues0.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossNetCashFlowHedgeParent0.40.30.30.00.7-1.11.20.00.30.60.50.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-30
Value-162000000-7-17000000-100010
Percentage of NonoperatingIncomeExpense13.6-5.9-2.2-0.40.12.8-0.1-0.018.527.02.10.11.9-0.01.0-0.08.41.80.70.6207.8
Percentage of Revenues-0.50.10.00.00.0-0.0-0.00.0-0.2-0.5-0.0-0.0-0.00.0-0.00.0-0.0-0.0-0.0-0.00.4
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value002221000
Percentage of NonoperatingIncomeExpense-0.7-0.8-8.1-1.10.6-5.20.0-0.0-0.0
Percentage of Revenues0.00.00.10.10.10.00.00.00.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest0.00.00.00.00.00.00.00.00.0

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2922762112484224693692633221566383269239190337353356257330292281268274268178186159651311218210412795117787510275
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues8.37.55.96.912.113.310.87.910.347.412.58.88.56.611.412.213.19.111.911.311.010.210.911.18.410.29.24.69.58.56.47.99.77.99.86.56.48.46.8

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value000000000000
Percentage of IncomeTaxExpenseBenefit-0.0-0.1-0.0-0.0-0.00.00.00.00.00.00.00.0
Percentage of Revenues-0.0-0.0-0.0-0.0-0.00.00.00.00.00.00.00.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossNetCashFlowHedgeParent-0.4-0.8-0.3-0.3-0.7-0.00.01.00.30.60.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value30000000160000000000000-3000-100
Percentage of IncomeTaxExpenseBenefit1.2-0.2-0.0-0.0-0.00.00.00.00.50.40.10.00.10.10.00.10.00.00.20.00.00.00.0-1.30.0-0.10.0-2.10.10.2
Percentage of Revenues0.1-0.0-0.0-0.0-0.00.00.00.00.10.20.00.00.00.00.00.00.00.00.00.00.00.00.0-0.10.0-0.00.0-0.10.00.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Taxes Paid Net

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value1392143915451494140894414429151171-1661226862747647103010489698281019924820882856723479457487490426292398387302300353304308271112294220306279144246
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.439.242.941.340.426.842.027.337.4-5.039.828.026.622.634.936.235.529.236.735.732.133.434.129.922.523.326.728.530.220.628.827.223.422.627.025.225.722.39.524.319.827.225.013.323.8

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
Value1385139617061461142995414579081185-286123584974263010141026935764909896811861845710485513503414397354311334333332
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 Revenues39.238.047.440.441.027.142.427.137.9-8.740.127.626.421.934.335.534.326.932.734.631.832.633.729.322.828.129.229.328.724.924.125.627.627.6

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value-50000881-481-13100012112-532200-8000000011817
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.00.0100.00.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.2-0.00.00.00.02.50.0-1.40.1-4.00.00.00.00.00.10.00.10.1-1.90.10.10.00.0-0.40.00.00.00.00.00.0-0.00.11.61.4

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1379139617061460142995214569571184-155123584974262810121024933762962894809861844718485513503414397353311266334333332258136239189
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.038.047.440.441.027.042.328.537.8-4.740.127.626.421.934.235.434.226.834.734.531.732.633.629.722.828.129.229.328.724.924.120.125.627.627.621.211.619.717.1

Net Income Loss

us-gaap:NetIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value1399143915451494140894614448661172-297122686274764910321049970831965927822883856714479457487490426292398386302300351288294240254293217305277142244
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.639.242.941.340.426.842.025.837.5-9.039.828.026.622.634.936.335.629.334.835.832.233.534.129.522.523.326.728.530.220.628.827.223.422.626.923.824.519.721.624.219.627.124.813.123.5

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-30
Value14403731169-8-10-37-28-18-264-5-48534240341320-40-70
Percentage of NetIncomeLoss1.12.82.42.11.21.0-0.6-1.2-3.29.7-1.5-0.30.80.7-0.5-0.40.96.44.44.34.21.50.30.1-0.90.0-1.5-0.0
Percentage of Revenues0.41.11.00.90.50.3-0.3-0.3-1.2-0.9-0.6-0.10.20.2-0.2-0.20.31.91.51.51.40.50.10.0-0.20.0-0.4-0.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1399143915451494140894614448661172
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.639.242.941.340.426.842.025.837.5
Percentage of Revenues us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.0

Net Income Loss Available To Common Stockholders Basic

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value-60000-1-148-1131000-1-2-1-1-253-2-2008000000001161431-141120122
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.00.00.00.00.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-0.20.00.00.00.0-0.1-0.01.4-0.14.00.00.0-0.0-0.0-0.1-0.0-0.1-0.11.9-0.1-0.1-0.0-0.00.4-0.00.00.00.00.00.0-0.0-0.00.11.31.22.6-12.10.10.20.00.20.20.3

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-60000-1-148-1
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.00.00.00.00.0100.0100.0100.0100.0
Percentage of Revenues-0.20.00.00.00.0-0.1-0.01.4-0.1
Percentage of Revenues us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.0

Assets

us-gaap:Assets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value261192723427484262872644525288254922395226090236522307321759211952287622104215142067419504207281675915219143161370412917122301186311250108411016410130963091629113904988028621829380928551
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

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
Value13582138951349213338126231225711732116991205211054102241018597281074899901011110346101291016141863549350232733352308932423124293928253166296828912805262225682565261926432289
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 Assets52.051.049.150.747.748.546.048.846.246.744.346.845.947.045.247.050.051.949.025.023.324.523.926.025.327.327.827.127.831.330.831.630.829.029.229.831.632.726.8

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
Value261192723427484262872644525288254922395226090236522307321759211952287622104215142067419504207281675915219143161370412917122301186311250108411016410130963091629113904988028621829380928551
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

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
Value1254613343139951295213829130391376612260140531261212860115851147912140121171140310326937210572125721166610809104279561913686208125790173396961665962686305642562295977560453966221
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 Assets48.049.050.949.352.351.654.051.253.953.355.753.254.253.154.853.049.948.151.075.076.775.576.174.074.772.772.272.972.268.769.168.469.271.070.869.367.666.772.8

Assets Current

us-gaap:AssetsCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value8007838184487909894276408719743210195787375687108685987328091744772016700927056185258467243723925352531842643252353283244305528682677297528372688262825402480
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.730.830.730.133.830.234.231.039.133.332.832.732.438.236.634.634.834.444.733.534.632.631.930.428.826.823.523.352.432.031.731.329.432.932.231.231.731.429.0

Cash And Cash Equivalents At Carrying Value

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2092188019331959208819582017195119391787156716301501144114671293139512271327131013891292109110021018824891861753686661683684584581666687605551
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.06.97.07.57.97.77.98.17.47.66.87.57.16.36.66.06.76.36.47.89.19.08.07.88.36.97.97.97.46.86.97.57.56.56.67.78.37.56.4

Inventory Net

us-gaap:InventoryNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value858804751776770929916931890902100793692110011009996964893918865825804753715672659614570506447392362337326310308289
Percentage of InventoryNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.33.02.73.02.93.73.63.93.43.84.44.34.34.44.64.64.74.64.45.25.45.65.55.55.55.65.55.35.04.44.14.03.73.63.53.63.6

Inventory Finished Goods

Inventory Finished Goods And Work In Process

Other Assets Current

us-gaap:OtherAssetsCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value6836317439809656878488438959629671146123110939931027941836861750579447396346295226205173169136126149122144194201186215177
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.62.32.73.73.72.73.33.53.44.14.25.35.84.84.54.84.64.34.24.53.83.12.92.72.41.91.81.61.71.31.31.61.31.62.22.32.22.72.1

Land

Machinery And Equipment Gross

Noncurrent Assets

Property Plant And Equipment Gross

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1636159015551886184117971730167116311559158015111438143915281471139413301320127412171186124612101163111810741030983941-898854821782749771789767642
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.35.85.77.27.07.16.87.06.36.66.96.96.86.36.96.86.76.86.47.68.08.39.19.49.59.49.59.59.79.3-9.39.39.08.68.58.99.59.57.5

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value328132473138307730133601353834093334318229952827261025012387230122582187202718371739176517241756174417501806178717361742167616221617157115721712167316411637
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets12.611.911.411.711.414.213.914.212.813.513.013.012.310.910.810.710.911.29.811.011.412.312.613.614.314.816.116.517.117.217.417.717.717.417.919.920.220.319.1

Goodwill

us-gaap:Goodwill



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-31
Value5752575757465749563957065440517049074632412738703611366934193167291726632408215418491760154113641232123212101210121012011204119711931146114611461146114611381138
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets22.021.120.921.921.322.621.321.618.819.617.917.817.016.015.514.714.113.711.612.912.212.311.210.610.110.410.811.211.911.912.513.113.112.713.013.313.814.213.30.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value344635273392368130563120337936613794387940194051410338083869396740124085418142944353402841294249436444744580467815811631168117321783160816591678173117721871
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets13.213.012.314.011.612.313.315.314.516.417.418.619.416.617.518.419.420.920.225.628.628.130.132.935.737.740.743.215.616.117.518.919.617.818.819.520.921.921.9

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsNet

biib:OutLicensedPatents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value2426249700011357101316192328323743495561697785127134142149157164171179186196207227
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 Assets9.39.20.00.00.00.00.00.00.00.00.00.10.10.10.10.10.20.20.20.30.40.40.50.60.71.11.21.31.51.51.71.92.02.12.22.42.8
Percentage of Assets biib:OutLicensedPatents0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ProductOrService, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

biib:AVONEX, us-gaap:DevelopedTechnologyRights



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value154236246256265275285
Percentage of FiniteLivedIntangibleAssetsNet6.429575.027400.028466.726500.016194.18405.9
Percentage of Assets0.60.90.91.01.01.11.2
Percentage of Assets biib:AVONEX us-gaap:DevelopedTechnologyRights0.00.00.00.00.00.00.0

biib:TysabriProduct, biib:InLicensedPatents



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value1800188919331980202720732120
Percentage of FiniteLivedIntangibleAssetsNet74.2236200.0214811.1220088.9202710.0121976.562376.5
Percentage of Assets6.96.97.47.58.08.18.9
Percentage of Assets biib:TysabriProduct biib:InLicensedPatents0.00.00.00.00.00.00.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1130125212381306189816901009902380102713001268118413351239115310941107892751640618565611639594636533306274271271368331237211228248230
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.34.64.55.07.26.74.03.81.54.35.65.85.65.85.65.45.35.74.34.54.24.34.14.75.25.05.74.93.02.72.83.04.03.72.72.52.83.12.7

Liabilities Current

us-gaap:LiabilitiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value4638486344323210314832953174315231523368344833792992341924992516277625772633255519462219194019161594175815181304128116571521143213379128859549781050714
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets17.817.916.112.211.913.012.513.212.114.214.915.514.114.911.311.713.413.212.715.312.815.514.214.813.014.813.512.012.616.415.815.614.710.110.111.111.813.08.4

Debt Current

Notes Payable Current

us-gaap:NotesPayableCurrent



Period End2020-03-312019-12-312019-09-302018-12-312013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value15011495149502034534534534533313113413719
Percentage of NotesPayableCurrent100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.75.55.40.02.04.54.74.95.00.00.01.51.61.70.2

Accounts Payable Current

us-gaap:AccountsPayableCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value389530382377378370342295345395298330316279274225271267251282236229233224212219166163165203157159173186159170159162118
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.91.41.41.41.51.31.21.31.71.31.51.51.21.21.01.31.41.21.71.61.61.71.71.71.91.51.51.62.01.61.71.92.11.82.01.92.01.4

Other Accrued Liabilities Current

us-gaap:OtherAccruedLiabilitiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value662726677727708609640638653636606591475685566613582579549433403456276263285
Percentage of OtherAccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.52.72.52.82.72.42.52.72.52.72.62.72.23.02.62.92.83.02.62.62.73.22.02.02.4

Taxes Payable Current

us-gaap:TaxesPayableCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3107112542723863254223231681215270231208212496208458457322168159192161179144812820445850454710938475
Percentage of TaxesPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.20.30.51.60.90.31.00.90.90.30.50.20.31.00.91.02.41.12.22.72.11.21.21.51.31.51.30.80.30.20.50.60.50.50.50.11.11.00.9

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2437276524292318243528612578263325712901245524362044290320122072200320961918181213841819154414951216135512041056885979866762660677674641591665500
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets9.310.28.88.89.211.310.111.09.912.310.611.29.612.79.19.69.710.89.310.89.112.711.311.69.911.410.79.78.79.79.08.37.27.57.77.47.18.25.9

Long Term Debt

us-gaap:LongTermDebt



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value4459445944585948594359365931592859295935593859545952651265296538653565216529576580582583586591592694726687
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets17.116.416.222.622.523.523.324.822.725.125.727.428.128.529.530.431.633.431.53.43.84.14.34.54.85.06.26.76.8

Deferred Tax Liabilities Noncurrent

Minority Interest

us-gaap:MinorityInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value-10-4-4-4-7-8-6-7-16-14-11-11-11-11-2012-5025334000022221479705239404140
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.0-0.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.90.80.70.00.00.00.5

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value-10-4-4-4-7-8-6-7-16-14-11250
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.099.4100.7
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.10.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1357134813701355135313891511145716401628716750688722862951916905861915892650658710702659608595674604539534517400384351356325254
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.25.05.05.25.15.55.96.16.36.93.13.53.23.23.94.44.44.64.25.55.94.54.85.55.75.65.45.56.66.05.65.85.74.44.44.14.34.03.0

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
Value1254613343139951295213829130391376612260140531261212860115851147912140121171140310326937210572125721166610809104279561913686208125790173396961665962686305642562295977560453966221
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 Assets48.049.050.949.352.351.654.051.253.953.355.753.254.253.154.853.049.948.151.075.076.775.576.174.074.772.772.272.972.268.769.168.469.271.070.869.367.666.772.8

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value125361333913991129481382213031137591225314037125981284811573114671212812114114031032893741056612572116691081410430956591418620812579027339696366616270630864266233605656745449626158335554
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets48.049.050.949.352.351.554.051.253.853.355.753.254.153.054.853.050.048.151.075.076.775.576.174.074.772.772.272.972.268.769.268.469.271.070.870.268.467.373.20.00.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-149-135-92-252-219-240-248-261-30331831922459-27-55-26-2150-1179
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-1.2-1.0-0.7-2.0-1.6-1.8-1.8-2.1-2.22.52.62.40.6-0.3-0.8-0.4-0.40.8-0.21.4
Percentage of Assets-0.6-0.5-0.3-1.0-0.8-1.0-1.0-1.1-1.21.31.41.10.4-0.2-0.5-0.3-0.30.60.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value0000004700970041964023385441853895578160735807
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.00.00.00.00.00.30.00.00.80.00.038.846.755.465.171.592.3104.1104.6
Percentage of Assets0.00.00.00.00.00.00.20.00.00.40.00.029.333.938.146.248.167.60.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value00000000000000000000
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value156731645517065161821702616257169441549917334158101507112208928363494486310618721068270-352
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest125.0123.4122.0125.0123.2124.8123.1126.5123.5125.5124.3130.285.973.664.448.334.417.14.6-6.3
Percentage of Assets60.060.462.161.664.464.366.564.766.466.865.962.664.853.544.334.323.112.50.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2977-2977-2977-2977-2977-2977-2977-2977-29772977261126112611-1724-1324-839-349-679-5270
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-23.7-22.3-21.3-23.0-21.5-22.8-21.6-24.3-21.223.621.527.924.2-20.0-19.0-13.1-6.4-10.9-9.00.0
Percentage of Assets-11.4-10.9-10.8-11.3-11.3-11.8-11.7-12.4-11.412.611.413.418.2-14.5-13.1-9.3-4.3-8.00.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

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
Value100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0124000.0129000.0129000.0129000.0129000.0128000.0128000.0128000.0128000.0128000.0128000.0127000.0127000.0127000.0129000.0128000.0128000.0127000.0125000.0124000.0144000.0
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

Additional Paid In Capital

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
Value000000470097591900069180134242514242419641504106405440233987391738583854381938254217418541434224397538955781
Percentage of AdditionalPaidInCapital100.00.00.00.00.00.0100.00.00.0100.0100.0100.00.00.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.20.00.00.40.30.10.00.00.00.30.10.06.525.427.929.330.331.833.233.935.436.138.038.139.741.846.346.247.149.047.948.167.6

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
Value156731645517065161821702616257169441549917334158101610714881147811507115030142291317912208119991103310106928384007543682963495891540449134486419437963409310628062454216618721068
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 Assets60.060.462.161.664.464.366.564.766.466.869.868.469.765.968.066.163.762.657.965.866.464.861.358.455.853.552.449.848.344.343.641.437.434.331.928.526.123.112.5

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value-149-135-92-252-219-240-248-261-303-316-318-329-338-325-319-300-282-259-224-157-101-70-59-37-26-22-27-29-55-67-55-51-50-17-267250-2150
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.6-0.5-0.3-1.0-0.8-1.0-1.0-1.1-1.20.0-1.3-1.4-1.6-1.5-1.4-1.4-1.3-1.3-1.1-0.8-0.6-0.5-0.4-0.3-0.2-0.2-0.2-0.3-0.5-0.7-0.5-0.5-0.6-0.2-0.30.10.3-0.0-0.30.6

us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-31
Value-32-32-29-30-30-31-36-36-37-36-36-33-33-32-32-36-36-37-37-27-27-30-31-18-19-18-19-18-19-20-21-90
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax21.424.332.312.114.013.014.713.912.311.611.610.19.810.010.212.113.014.516.917.227.243.053.148.271.284.170.663.135.230.239.233.9-0.9
Percentage of Assets-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.2-0.10.0-0.2-0.1-0.2-0.2-0.1-0.2-0.2-0.2-0.2-0.1-0.2-0.2-0.2-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.10.0
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312017-09-302017-06-302016-12-31
Value4177213513440-133-104-104-104-6957
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax-27.9-5.8-78.9-5.4-23.5-14.4-1.80.343.933.032.831.720.4-18.1
Percentage of Assets0.20.00.30.10.20.10.0-0.0-0.50.0-0.4-0.5-0.30.3
Percentage of Assets us-gaap:AccumulatedGainLossNetCashFlowHedgeParent0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-31
Value-34662-4-1-1-20-1-4-5-12-100610-1000007515934012
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax2.4-3.1-6.8-2.5-1.31.70.80.60.80.00.51.31.53.83.4-0.3-2.2-0.70.41.0-0.7-1.30.7-1.3-1.5-32.7-20.2-52.5-16.7-4.6-7.6-0.0-57.4
Percentage of Assets-0.00.00.00.00.0-0.0-0.0-0.0-0.00.0-0.0-0.0-0.0-0.1-0.00.00.00.0-0.0-0.00.00.0-0.00.00.00.10.00.10.10.00.00.00.2
Percentage of Assets us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312016-12-312015-12-31
Value482550291730000000
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax-32.2-18.6-54.6-11.5-8.0-1.5-0.0-0.0-0.0-0.0-0.0-0.0-0.0
Percentage of Assets0.20.10.20.10.10.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312018-01-012017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-31
Value-203-139-192-271-261-243-214-222-130-175-175-187-231-314-334-258-244-186-195-160-137-200-99-61-1710-9-43-51-27-50-24
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax136.2103.2208.0107.3118.8101.286.385.243.055.455.156.968.396.6104.585.986.371.787.3102.0135.6283.7166.8161.13.7-31.8-36.033.878.975.849.0189.6112.9
Percentage of Assets-0.8-0.5-0.7-1.0-1.0-1.0-0.8-0.9-0.50.0-0.7-0.8-1.1-1.5-1.5-1.2-1.1-0.9-1.0-0.8-0.8-1.3-0.7-0.4-0.00.10.1-0.1-0.4-0.5-0.3-0.6-0.3
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

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
Value297729772977297729772977297729772977297729772977297726112611261126112611261126112611261120842061172417241724136513651324130313031303839728728537349679
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 Assets11.410.910.811.311.311.811.712.411.412.612.913.714.011.411.812.112.613.412.615.617.218.215.216.014.114.515.312.613.413.113.514.214.39.38.38.46.54.38.0

Minority Interest

us-gaap:MinorityInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value-10-4-4-4-7-8-6-7-16-14-11-11-11-11-2012-5025334000022221479705239404140
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.0-0.00.00.0-0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.90.80.70.00.00.00.5

us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value-10-4-4-4-7-8-6-7-16-14-11250
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.099.4100.7
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.10.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value146719601694196414591895173510991457151816281169235157698699596310408951047733932914990104178635194473570429253431428428336
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues41.553.447.154.341.853.850.532.846.545.952.938.08.454.933.434.435.336.632.240.428.735.336.440.94.912.644.715.135.743.635.521.135.436.435.330.4

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value442708-365-110238-1625-619-11481346-769-1246-202-744-58136-736-1203-1807-989-1253-502-378-540-6305155-530-389-587-546-126-518-69683249
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.519.3-10.2-3.16.8-46.1-18.0-34.243.0-23.3-40.5-6.6-26.5-20.31.2-25.4-44.1-63.7-35.6-48.4-19.7-14.3-21.5-26.00.311.0-3.70.0-29.4-44.8-45.2-10.5-42.5-5.956.422.5

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-2245-2116-689-2375-679-143725-2791-268-708-19-751-901-721-300-1347-19982907-380-513-35-322114-238-417-416-142-9921-99225-461-1026-523
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-63.5-57.6-19.1-65.7-19.5-40.80.7-83.2-8.6-21.4-0.6-24.4-32.1-25.1-10.2-0.51.7-70.4104.7-0.13.2-19.4-1.4-13.35.4-16.8-29.4-32.2-10.8-7.61.8-8.318.5-39.2-84.6-47.2

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value146719601694196414591895173510991457151816281169235157698699596310408951047733932914990104178635194473570429253431428428336
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues41.553.447.154.341.853.850.532.846.545.952.938.08.454.933.434.435.336.632.240.428.735.336.440.94.912.644.715.135.743.635.521.135.436.435.330.4

Net Income Loss

us-gaap:NetIncomeLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value1399143915451494140894614448661172-297122686274764910321049970831965927822883856714479457487490426292398386302300351288294240254293217305277142244
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.639.242.941.340.426.842.025.837.5-9.039.828.026.622.634.936.335.629.334.835.832.233.534.129.522.523.326.728.530.220.628.827.223.422.626.923.824.519.721.624.219.627.124.813.123.5

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-30
Value14403731169-8-10-37-28-18-264-5-48534240341320-40-70
Percentage of NetIncomeLoss1.12.82.42.11.21.0-0.6-1.2-3.29.7-1.5-0.30.80.7-0.5-0.40.96.44.44.34.21.50.30.1-0.90.0-1.5-0.0
Percentage of Revenues0.41.11.00.90.50.3-0.3-0.3-1.2-0.9-0.6-0.10.20.2-0.2-0.20.31.91.51.51.40.50.10.0-0.20.0-0.4-0.0
Percentage of Revenues us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1399143915451494140894614448661172
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.639.242.941.340.426.842.025.837.5
Percentage of Revenues us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312009-09-302009-06-302009-03-31
Value1392143915451494140894414429151171-1661226862747647103010489698281019924820882856723479457487490426292398387302300353304308271112294220306279144246
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues39.439.242.941.340.426.842.027.337.4-5.039.828.026.622.634.936.235.529.236.735.732.133.434.129.922.523.326.728.530.220.628.827.223.422.627.025.225.722.39.524.319.827.225.013.323.8

Depreciation Depletion And Amortization

us-gaap:DepreciationDepletionAndAmortization



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value1191133291171213293461711688917730251217718017514915615114414715717516419097
Percentage of DepreciationDepletionAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Other Operating Capital Net

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-06-302011-03-31
Value-182-19-90171-8689-2820-18621533448-12-35-14-9055-36953-66-3175-35502075-6
Percentage of IncreaseDecreaseInOtherOperatingCapitalNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Inventories

us-gaap:IncreaseDecreaseInInventories



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value62666120-12920-842-2-7585394610263988246959216647551660192311186205-9-12
Percentage of IncreaseDecreaseInInventories100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value442708-365-110238-1625-619-11481346-769-1246-202-744-58136-736-1203-1807-989-1253-502-378-540-6305155-530-389-587-546-126-518-69683249
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues12.519.3-10.2-3.16.8-46.1-18.0-34.243.0-23.3-40.5-6.6-26.5-20.31.2-25.4-44.1-63.7-35.6-48.4-19.7-14.3-21.5-26.00.311.0-3.70.0-29.4-44.8-45.2-10.5-42.5-5.956.422.5

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value14911090186127225163186194230229197210182170136126186229129971066264543372547051543248384738
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-2245-2116-689-2375-679-143725-2791-268-708-19-751-901-721-300-1347-19982907-380-513-35-322114-238-417-416-142-9921-99225-461-1026-523
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-63.5-57.6-19.1-65.7-19.5-40.80.7-83.2-8.6-21.4-0.6-24.4-32.1-25.1-10.2-0.51.7-70.4104.7-0.13.2-19.4-1.4-13.35.4-16.8-29.4-32.2-10.8-7.61.8-8.318.5-39.2-84.6-47.2

Repayments Of Long Term Debt

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312014-09-302014-06-302014-03-312013-09-302013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value222020937172401655135202750250007815836513480020012955526233360-35941446463111019119504681031577
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0100.00.0100.0100.00.00.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0

us-gaap:ShareRepurchaseProgram

biib:December2019ShareRepurchaseProgram



Period End2020-03-31
Value941
Percentage of PaymentsForRepurchaseOfCommonStock42.4

biib:March2019ShareRepurchaseProgram



Period End2020-03-31
Value1300
Percentage of PaymentsForRepurchaseOfCommonStock58.6

us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

biib:March2019ShareRepurchaseProgram, us-gaap:SubsequentEvent



Period End2020-04-22
Value1300
Percentage of PaymentsForRepurchaseOfCommonStock0.0

Repayments Of Long Term Debt

Debt Instrument Interest Rate Stated Percentage

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.1720.00.1190.1410.2270.0289999999999999980.2040.2240.2160.240.2380.2380.242-0.00500000000000000440.2470.2520.269-0.00200000000000000180.2430.2390.256-0.0070000000000000060.2420.270.2680.2740.2440.1320.2470.2380.2140.00.2640.2380.276-0.017999999999999960.4010.2580.255
Percentage of EffectiveIncomeTaxRateContinuingOperations100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

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

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

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

Share Based Compensation

us-gaap:ShareBasedCompensation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value673845524538373843303030373733384529374152353537463628322629243333394451
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

Deferred Tax Assets Net

Unrecognized Tax Benefits

Deferred Tax Assets Valuation Allowance

Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value4224274224344470
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 End2020-03-312019-12-312019-03-312018-12-31
Value2591291322431224
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0

biib:AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value16501724416-6-3-30-64-102041-499181314-110-2234126
Percentage of AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ValuationAllowancesAndReservesType

biib:ContractualAdjustments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value15741625314-5-2-3-1-90-12120-1-419101024-92-3234135
Percentage of AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears94.1127.64800.093.9102.461.285.287.157.1105.6122.2147.6-16.7123.861.5-10.2-78.697.911.6106.755.179.7172.982.9-233.3124.078.6112.995.858.8150.084.4

biib:ReserveforCashDiscounts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value0000000
Percentage of AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears3.0-12.10.03.9-1.20.00.0

us-gaap:SalesReturnsAndAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-03-312011-12-312011-03-31
Value00-40012-200026375006251-10-1-40001
Percentage of AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears3.0-15.5-4700.02.2-1.238.814.837.18.6-8.3-22.2-33.3131.2-33.738.5114.3-7.12.170.524.431.914.3-71.48.5488.98.0-22.64.215.6

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

biib:Biogenshareofcopromotionprofitsorlosses

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-09-302018-09-302018-06-302018-03-31
Value0.50.00.00.00.5
Percentage of Biogenshareofcopromotionprofitsorlosses100.00.00.00.0100.0

biib:Collaborationprofitlosssharing



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-30
Value716063584739423526204-5000
Percentage of Collaborationprofitlosssharing100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-30
Value716063584739433425207
Percentage of Collaborationprofitlosssharing100.099.899.8100.0100.4101.3103.198.095.1100.0157.4

us-gaap:TypeOfArrangement

biib:ContractOptionExerciseFee

biib:SamsungBiosimilarAgreement



Period End2020-03-31
Value60
Percentage of ContractOptionExerciseFee100.0

biib:CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value10331052935884826922833826806794711705707724685641616593553529553462429374378176141146122121109119
Percentage of CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ValuationAllowancesAndReservesType

biib:ContractualAdjustments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value82786175871068073766164664162656155156850956149348045442341344135133028429313711010993928391
Percentage of CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear80.181.981.180.482.379.979.378.379.578.978.978.380.470.381.977.077.876.676.578.079.876.076.975.877.577.777.975.276.276.475.976.8

biib:ReserveforCashDiscounts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value200185171167141180165
Percentage of CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear19.417.718.319.017.119.619.9

us-gaap:SalesReturnsAndAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value4455456556477758811781011127731104433
Percentage of CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear0.50.50.60.70.60.60.80.70.70.90.71.11.11.00.81.41.41.91.31.71.82.52.92.01.92.11.17.03.93.52.73.2

us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

biib:Derivativesusedinnetinvestmenthedgenetoftaxexcludedcomponentincreasedecrease

us-gaap:NetInvestmentHedging



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0-41240000
Percentage of Derivativesusedinnetinvestmenthedgenetoftaxexcludedcomponentincreasedecrease100.0100.0100.0100.0100.00.00.00.00.0

biib:EffectiveTaxRateReconciliationGILTItax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.006-0.00100000000000000090.0160.0140.0190.0020.0130.0180.013
Percentage of EffectiveTaxRateReconciliationGILTItax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MajorCustomers

biib:EntityWidePercentageOfRevenueFromMajorDistributors

biib:DistributorOne



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value0.30.2870.3050.3130.3070.3250.340.3370.3430.368
Percentage of EntityWidePercentageOfRevenueFromMajorDistributors100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:DistributorTwo



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value0.1460.1840.1820.1420.1930.1860.1590.2080.2280.193
Percentage of EntityWidePercentageOfRevenueFromMajorDistributors48.764.159.745.462.957.246.861.766.552.4

us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement

biib:ExpenseIncurredByCollaboration

us-gaap:ResearchAndDevelopmentExpense, biib:UCBPharmaS.A.



Period End2020-03-31
Value9
Percentage of ExpenseIncurredByCollaboration100.0

us-gaap:TypeOfArrangement

biib:Eisai



Period End2020-03-31
Value43
Percentage of ExpenseIncurredByCollaboration457.9

biib:UCBPharmaS.A.



Period End2020-03-31
Value19
Percentage of ExpenseIncurredByCollaboration200.0

us-gaap:ProductOrService, us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement

biib:Expenseincurredbythecollaboration

biib:Aducanumab, us-gaap:ResearchAndDevelopmentExpense, biib:Eisai



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value1984316260647663667374
Percentage of Expenseincurredbythecollaboration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Aducanumab, us-gaap:SellingGeneralAndAdministrativeExpenses, biib:Eisai



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value22600201712147854
Percentage of Expenseincurredbythecollaboration118.868.52.16.212.928.818.718.311.213.17.06.4

biib:E2609andBAN2401, us-gaap:SellingGeneralAndAdministrativeExpenses, biib:Eisai



Period End2020-03-31
Value4
Percentage of Expenseincurredbythecollaboration25.7

us-gaap:ProductOrService, us-gaap:IncomeStatementLocation, us-gaap:TypeOfArrangement

biib:Expensereflectedwithinstatementsofincome

biib:Aducanumab, us-gaap:ResearchAndDevelopmentExpense, biib:Eisai



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value104218951556563667374
Percentage of Expensereflectedwithinstatementsofincome100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Aducanumab, us-gaap:SellingGeneralAndAdministrativeExpenses, biib:Eisai



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value12300118593854
Percentage of Expensereflectedwithinstatementsofincome117.169.40.05.913.016.39.314.26.113.17.06.4

biib:E2609andBAN2401, us-gaap:SellingGeneralAndAdministrativeExpenses, biib:Eisai



Period End2020-03-31
Value2
Percentage of Expensereflectedwithinstatementsofincome22.9

us-gaap:TypeOfArrangement

biib:Eisai



Period End2020-03-31
Value21
Percentage of Expensereflectedwithinstatementsofincome207.6

us-gaap:MajorCustomers

biib:OtherrevenuesfromantiCD20therapeuticprograms

biib:RocheGroupGenentech



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value17921920219912616915313193948149
Percentage of OtherrevenuesfromantiCD20therapeuticprograms100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-30
Value3839188427232947807066542996857105422946336505532625155084252174313633191226311344114101
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ValuationAllowancesAndReservesType

biib:ContractualAdjustments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-30
Value310732682593233601553504227529577418231446524417187386387317166329273238914483318776
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear80.979.881.082.179.377.178.477.076.077.381.277.178.870.580.675.471.675.076.374.676.676.375.274.774.869.673.771.076.576.1

biib:ReserveforCashDiscounts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value7318615912860178151
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear19.120.319.017.820.622.821.4

us-gaap:SalesReturnsAndAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-30
Value0000000000000-11001000210003000
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear0.0-0.10.00.10.00.00.1-0.00.10.00.00.00.0-0.20.20.10.10.20.10.00.30.60.40.00.10.02.70.20.10.0

biib:PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-30
Value54915701644742240171412156012133733128163283301589216-277572081002673610
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ValuationAllowancesAndReservesType

biib:ContractualAdjustments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-30
Value43211591273781125143326105211126725125155229241684170-7684115983226026
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear78.777.384.577.479.650.262.983.479.169.786.392.279.374.998.094.981.180.6109.794.278.8308.787.973.176.383.184.882.243.867.3

biib:ReserveforCashDiscounts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value112-17299216
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear20.4-10.710.618.119.45.916.7

us-gaap:SalesReturnsAndAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-30
Value4537498485565354521344812833224
Percentage of PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear0.933.35.04.41.043.920.42.82.138.89.05.21.610.94.43.01.98.67.13.62.1-178.311.121.24.03.913.83.145.339.6

us-gaap:TypeOfArrangement

biib:PercentageoffuturedevelopmentcostsrelatedtoEisai

biib:Eisai



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.450.00.00.00.45
Percentage of PercentageoffuturedevelopmentcostsrelatedtoEisai100.00.00.00.0100.0

biib:ShareBasedCompensationExpenseIncludedInCostsAndExpenses



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value7442478046364640474040344542504551372546875656557458665744414737353538474148
Percentage of ShareBasedCompensationExpenseIncludedInCostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:MajorCustomers

biib:ShareOfCoPromotionProfits

biib:RocheGroupGenentech



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value341381393377390365358359349320325347323
Percentage of ShareOfCoPromotionProfits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllocatedShareBasedCompensationExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312011-12-312011-09-302011-06-302010-12-312010-09-302010-06-30
Value-69394755494040414663636264249
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AwardType

biib:CashSettledPerformanceShares



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-30
Value-100-1504723740-93
Percentage of AllocatedShareBasedCompensationExpense2.30.60.7-2.014.4-1.79.20.00.00.00.00.00.00.00.0

biib:EmployeeStockPurchasePlan



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-30
Value213412312322323
Percentage of AllocatedShareBasedCompensationExpense-3.33.66.29.44.75.18.40.00.00.00.00.00.00.00.0

biib:MarketStockUnits



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-30
Value19977776439571379
Percentage of AllocatedShareBasedCompensationExpense-27.619.514.215.718.317.113.10.00.00.00.00.00.00.00.0

biib:PerformanceStockUnitsSettledinCash



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value8101100000
Percentage of AllocatedShareBasedCompensationExpense-12.92.71.62.02.70.70.20.00.00.0

biib:PerformanceStockUnitsSettledinStock



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value10-1122110000
Percentage of AllocatedShareBasedCompensationExpense-14.9-2.322.04.13.23.41.50.00.00.0

biib:TimeVestedRestrictedStockUnits



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-30
Value373731342930362627262833303031
Percentage of AllocatedShareBasedCompensationExpense-54.279.357.870.874.073.977.30.00.00.00.00.00.00.00.0

us-gaap:PerformanceShares



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-30
Value0000320314916-21
Percentage of AllocatedShareBasedCompensationExpense0.10.40.51.07.44.8-1.70.00.00.00.00.00.00.00.0

us-gaap:IncomeStatementLocation

us-gaap:Parent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value613539663830393339292925333036333627193360394039514046403129
Percentage of AllocatedShareBasedCompensationExpense-89.090.683.3120.979.274.997.080.984.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ResearchAndDevelopmentExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value331115282115211721181917181822212120102235242424292023251818
Percentage of AllocatedShareBasedCompensationExpense-48.130.232.251.144.337.652.042.546.90.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:SellingGeneralAndAdministrativeExpenses



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-30
Value43313454272229252823231829273128342817265534343347403945
Percentage of AllocatedShareBasedCompensationExpense-62.379.971.599.656.755.872.860.961.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-693947554940404146
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.599.5100.0100.0

us-gaap:AllocatedShareBasedCompensationExpenseNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-30
Value76434982493850425042433648465350543928489158585876666069
Percentage of AllocatedShareBasedCompensationExpenseNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AmortizationOfIntangibleAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value71-1482837068-112281107103139108117448104999288969892951071221161439982515352455049555353535348
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect



Period End2020-03-312019-03-31
Value-3351019
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleRealizedGain



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value501000101
Percentage of DebtSecuritiesAvailableForSaleRealizedGain100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtSecuritiesAvailableForSaleRealizedLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value1900000911
Percentage of DebtSecuritiesAvailableForSaleRealizedLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxExpenseBenefit



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value3638-43-15622815312-11053131-19-9676-118-26-39840-95-10716-78-82-66-79-66-39-33767-2371-20-30-388
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Depreciation



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value484545475275646465
Percentage of Depreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet

us-gaap:ForeignExchangeContract, biib:Cashflowsoperatingexpenses, us-gaap:OperatingExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0-100000010000
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ForeignExchangeContract, biib:Cashflowsrevenue, us-gaap:Sales



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value27383529149-8-10-32-17-18-36
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet-27000.0-2984.6-4400.0-4257.1-2960.0-2300.02800.02600.0-2530.817400.0-3760.0-1000.0-6700.0

us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation

us-gaap:DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet

us-gaap:ForeignExchangeContract, biib:Cashflowsoperatingexpenses, us-gaap:OperatingExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value010000000
Percentage of DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ForeignExchangeContract, biib:Cashflowsrevenue, us-gaap:Sales



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value9-50333070
Percentage of DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet-1033.3-530.0200.0-1233.3-411.1-3500.075.0-7900.0300.0

us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation

us-gaap:NetInvestmentHedging, us-gaap:OtherNonoperatingIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value002221000
Percentage of DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet-100.040.0550.0-733.3-244.4-1500.00.0-0.0-0.0

us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:DiscontinuedOperationTaxEffectOfDiscontinuedOperation

biib:DenmarkManufacturingOperations



Period End2020-03-312019-12-312019-09-30
Value5943
Percentage of DiscontinuedOperationTaxEffectOfDiscontinuedOperation100.0100.0100.0

us-gaap:DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0-40-17-21150000
Percentage of DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown0.0100.0100.0100.0100.00.00.00.00.0

us-gaap:EffectOfExchangeRateOnCashAndCashEquivalents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1217-19204-5-170-1516297-320-1515-15-613-37-22-15-30-3-64-2-624-58-4-5
Percentage of EffectOfExchangeRateOnCashAndCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.210.00.210.210.210.00.210.210.210.00.350.350.350.00.350.350.350.00.350.350.350.00.350.350.350.350.350.350.350.350.350.00.350.350.350.00.350.350.35
Percentage of EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationDispositionOfAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.0-0.0049999999999999990.00.00.0430.00.00.00.0
Percentage of EffectiveIncomeTaxRateReconciliationDispositionOfAssets0.0100.00.00.0100.00.00.00.00.0

us-gaap:EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value-0.0410.0020000000000000018-0.05-0.046-0.046-0.020.0080.0-0.0070.0030000000000000027-0.114-0.117-0.112-0.0020000000000000018-0.101-0.1-0.0810.0010000000000000009-0.107-0.111-0.084-0.006000000000000005-0.093-0.087-0.084-0.066-0.072-0.099-0.071-0.076-0.082-0.038-0.073-0.056
Percentage of EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepreciationAndAmortization



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value0.0020.00.0040.0040.0030.0070.0030.0060.0060.00100000000000000090.0120.0140.0140.00100000000000000090.0120.0110.011-0.0020.0150.0110.010.00100000000000000090.0070.0120.0150.0190.0180.0110.0130.0110.0110.00.0110.0140.0140.00100000000000000090.0290.015
Percentage of EffectiveIncomeTaxRateReconciliationNondeductibleExpenseDepreciationAndAmortization100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value0.0020.0-0.0010.0040.0040.00.0030.0040.0040.00.0060.0070.0070.00.0020.0060.0060.0010.0050.0090.0060.0010.0040.0040.003-0.003-0.010.055-0.021-0.024-0.0390.0-0.012-0.011-0.0130.0010000000000000009-0.038-0.017
Percentage of EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationOtherAdjustments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-0.0030.002-0.0080.005-0.0020.004-0.010.0050.002-0.0060.0040.0060.010.00.0050.0030.0030.00.00.0040.0010.003-0.0120.0040.005-0.004-0.002-0.002-0.0050.0020.0020.0009999999999999992-0.009-0.005-0.023-0.008-0.0010.002-0.007
Percentage of EffectiveIncomeTaxRateReconciliationOtherAdjustments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.0060.0010.0090.0090.004-0.0010.0060.0060.0090.0020.0070.0080.001-0.00100000000000000090.0110.010.010.00.0120.004-0.0040.00.0120.0110.0120.0250.0190.0770.0080.0080.0080.0030000000000000010.0130.0040.024-0.0029999999999999990.0240.0190.019
Percentage of EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCredits



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.010.00099999999999999920.0150.0090.0080.00099999999999999920.010.0070.0080.00.0070.0090.0070.00100000000000000090.0140.012-0.012-0.004-0.011-0.007-0.007-0.002999999999999999-0.006-0.007-0.013-0.022-0.035-0.033-0.034-0.039-0.037-0.005999999999999998-0.051-0.041-0.021-0.008-0.043-0.016-0.016
Percentage of EffectiveIncomeTaxRateReconciliationTaxCredits100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1112313232222-25343-19223-17222-2-2-2-1117-1-1-1-1000
Percentage of EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value13681375767111081211141215961226161616221720161312-14-11-1010-12-14-13
Percentage of EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquitySecuritiesFvNiGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value-602-4-174375-111415
Percentage of EquitySecuritiesFvNiGainLoss100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquitySecuritiesFvNiRealizedGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value0-3-4420000
Percentage of EquitySecuritiesFvNiRealizedGainLoss0.0100.0100.0100.0100.0100.00.00.0

us-gaap:EquitySecuritiesFvNiUnrealizedGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-600-9-131375-1114150
Percentage of EquitySecuritiesFvNiUnrealizedGainLoss100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value4-25720-11-7987-15-1-30-21-104-5-10-2-2402-7-749-4005-2-9-12
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value00000810020000650030014005160507206
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements0.00.00.00.00.0100.00.00.0100.00.00.00.0100.0100.00.0100.00.00.0100.00.00.0100.0100.00.0100.0100.0100.0100.00.0100.0

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-18-2-41-230-13-1-26-24-7-402-13-4-1-13-2-4-1-3-3-5-20-110-4000-301
Percentage of ForeignCurrencyTransactionGainLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value2-81004-2555-11611201821981394721000515-41060-43-107
Percentage of GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value169917281779175818601414181211781493139916091132986838136714021325108513561222110211511136993665679652496530508384405480399426350187396295
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromEquityMethodInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-30
Value-14-12-21-16-280000000000000-6-400-5-1-7-6-2-3-1000
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-30
Value6100514-6-40-5-1-7-6-2-3-1
Percentage of IncomeLossFromEquityMethodInvestments-41.2-83.3-3.7-33.7-48.899.5100.495.9100.198.399.9100.5100.5100.0103.3

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-09-302019-06-30
Value142116
Percentage of IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions100.0100.0100.0

us-gaap:IncomeLossFromIndividuallySignificantComponentDisposedOfOrHeldForSaleExcludingDiscontinuedOperationsAttributableToParentBeforeIncomeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.040200000.017700000.02300000.0-115500000.00.00.00.00.0
Percentage of IncomeLossFromIndividuallySignificantComponentDisposedOfOrHeldForSaleExcludingDiscontinuedOperationsAttributableToParentBeforeIncomeTax0.0100.0100.0100.0100.00.00.00.00.0

us-gaap:IncreaseDecreaseInAccountsReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value238-710-133136-486653134209-751051953173-95160-9224-89128215108-819775-788956-37-35902649220
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccruedIncomeTaxesPayable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-06-302014-03-31
Value223-48-2421361706132-74257113328580-195-854-376225-409-103-5215449-18
Percentage of IncreaseDecreaseInAccruedIncomeTaxesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccruedLiabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-03-312012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-347349107-77-13836487135-121277-52231-684793-6018-180248-435-20522549141-171173126-180134-82901081-1491134159-82
Percentage of IncreaseDecreaseInAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDueFromRelatedParties



Period End2020-03-312019-03-31
Value-78600000.00.0
Percentage of IncreaseDecreaseInDueFromRelatedParties100.00.0

us-gaap:IncreaseDecreaseInEquitySecuritiesFvNi



Period End2020-03-312019-09-302019-06-302019-03-312018-09-30
Value-62-9-175375137
Percentage of IncreaseDecreaseInEquitySecuritiesFvNi100.0100.0100.0100.0100.0

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

biib:MarketStockUnits



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value00000000000000000000000000000000000
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.00.0100.00.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:PerformanceStockUnitsSettledinStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0000000000000
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.00.00.00.00.00.00.00.00.00.00.00.00.0

biib:TimeVestedRestrictedStockUnits



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value00000000000000000000000000000010111011
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.00.0100.00.0300.00.0400.0100.0200.00.0200.0100.0200.00.0100.0100.0200.0-0.0200.0200.0150.00.0250.0200.0200.0233.3200.0266.7300.0400.0366.7-200.0800.0700.0800.00.00.00.0

us-gaap:InvestmentIncomeInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value242930293131262826242016162016151195433322104510655433368
Percentage of InvestmentIncomeInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-30
Value-7-2036-200-2217-1-11-5420-20100-6166-1101-11
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0-2197-13717431-24-17-9-161-14-23-28-26-13-13923-8-8-31-9
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0-30005000-30003000-10021-130001
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax114.3103.40.4-7.71.629.9-4.32.82.020.1-0.03.710.0-26.6-1.7-2.5-0.881.8-3.729.25.5164.2-8.25.466.7-13.3

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value60-2793-83139-3122-60-17-53
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax8671.4955.247.3684.683.6220.9-73.9386.4247.596.6571.3

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-200037-200-8-907-2-11-5420-301-10011
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax-2971.4-6.90.3-300.019.0-15.3-6.51.933.650.3-4.3-43.3-200.082.523.1-14.5-9.4-3.822.8-3.15.112.3-0.010.8150.0-17.8

us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value23-242313165000
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax3414.3858.611.8-1069.243.428.20.00.0-0.0

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-635279-10-17-298-924412438220-75-14-589-35-2363-100-38-60-8-2-24
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax-9128.6-1810.340.2792.3-47.7-163.8184.8-291.1-183.2-67.0-467.0-504.92000.0530.161.5205.7-36.1265.9172.8657.3-425.7469.1708.2218.9-241.7271.1

us-gaap:OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-30
Value33-6559-3716305132-290-35-103-2364129-47-21-31-96873048105-14-211-2718-18326
Percentage of OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-30
Value-13-42160-3320713421389-13-5172-18-23-35262-56-30-1141-11-452512-120-328-1829
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0000000000000-10021-130001
Percentage of OtherComprehensiveIncomeLossNetOfTax-5.90.5-0.32.9-1.52.1-3.80.04.4-1.9-2.2-3.0-0.6-4.1-0.9-9.2-11.8-31.7-6.24.614.8-9.5

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value3359-37165132-29-35
Percentage of OtherComprehensiveIncomeLossNetOfTax-250.436.8113.182.039.1313.9-223.1-377.7

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-703600-217-1-5420-20100-61-1
Percentage of OtherComprehensiveIncomeLossNetOfTax57.80.1-9.933.5-1.51.4-16.910.6-52.930.229.8-19.1-7.10.34.10.7-11.8-2.1-0.9159.631.58.7

us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value232111143000
Percentage of OtherComprehensiveIncomeLossNetOfTax-170.413.2-34.968.046.70.00.00.0

us-gaap:AccumulatedTranslationAdjustment



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-6379-10-178-9244438220-14-589-35-2363-100-38-60-8-2-24
Percentage of OtherComprehensiveIncomeLossNetOfTax473.349.430.7-86.463.9-217.5343.8467.0-608.8-377.479.6246.8-27.2-13.441.7-207.0913.1-90.5532.3187.4-53.8192.6

us-gaap:NoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value000000000
Percentage of OtherComprehensiveIncomeLossNetOfTax-4.4-0.00.01.20.0-1.30.0-1.21.5

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312013-03-31
Value-14-42160-33207134213-12
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-14-42160-33207134213
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-30
Value03000-50003000-3000100-2-1130000-1-100000
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherNoncashIncomeExpense



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-06-302011-03-31
Value-45183-40-500110-16-26-35-53-55-18-57-13-4020-50-37-2732-4531-77133-829719
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-06-302011-03-31
Value0-3105-101-1-15-20610-5322432623362246112194-25
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation



Period End2020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value29-6-832-4-7-621-5-7-725-3-9-729
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value1684197712508251319285519191557
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireInProcessResearchAndDevelopment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value750000027751000120000
Percentage of PaymentsToAcquireInProcessResearchAndDevelopment100.00.00.00.00.00.0100.0100.0100.00.00.0100.00.00.00.0

us-gaap:PaymentsToAcquireIntangibleAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312014-09-30
Value371550000030655058551110-2828-600
Percentage of PaymentsToAcquireIntangibleAssets100.0100.00.00.00.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:PaymentsToAcquireOtherProductiveAssets



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value00003003003003006003003003003003003003003003003000250200150025
Percentage of PaymentsToAcquireOtherProductiveAssets0.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-06-302012-03-312011-06-302011-03-31
Value4-4022128-3115-62-18-232310-4036-2324-12-7726-11-2-27-113301022184
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value2389213961117661489117911922733406810938881700188421932362164211816992387601373776625560757617784329491599
Percentage of ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesEquity



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value03166309000
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesEquity100.0100.0100.0100.00.00.00.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-14-40-37-31-16-98103728182-6-454-8-53-42-40-34-13-204-3
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-26-37-34-29-14-8810311718
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax181.893.292.791.285.690.898.9100.084.059.996.8

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value13-20000006110000000000000-60-2
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax-87.85.81.31.91.2-6.11.10.016.040.13.23.6-6.3-4.30.08.5-0.0-0.6-1.9-0.2-0.3-0.7-3.7928.6-2.473.0

us-gaap:AccumulatedOtherComprehensiveIncomeLossDerivativeQualifyingAsHedgeExcludedComponentIncludingPortionAttributableToNoncontrollingInterest



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value00-2-2-2-1000
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax6.11.05.96.913.215.30.00.00.0

us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-30
Value476691540484563611507981496587446796423533529473437541519490460500417447528410327284304329
Percentage of ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ResearchAndDevelopmentInProcess



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value7500000277510001200000
Percentage of ResearchAndDevelopmentInProcess100.00.00.00.00.00.0100.0100.0100.00.00.0100.00.00.00.00.0

us-gaap:BusinessAcquisition

biib:BIIB118



Period End2020-03-31
Value75
Percentage of ResearchAndDevelopmentInProcess100.0

us-gaap:RestructuringCharges



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-31
Value0000026110000111109930000000100101675
Percentage of RestructuringCharges0.00.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.00.0100.0100.00.00.00.00.00.00.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value000000000
Percentage of StockIssuedDuringPeriodSharesStockOptionsExercised100.00.0100.00.0100.00.00.00.0100.0

us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesTreasuryStockReissued

us-gaap:CommonStock



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value000000000
Percentage of StockIssuedDuringPeriodSharesTreasuryStockReissued100.00.0100.00.0100.0100.00.00.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-473014831137
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0000031137
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised-0.00.00.00.00.0100.0100.0100.0100.0

us-gaap:RetainedEarnings



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value47-1040148
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised-100.0-3371.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueTreasuryStockReissued



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value187791678816
Percentage of StockIssuedDuringPeriodValueTreasuryStockReissued100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value187791678816
Percentage of StockIssuedDuringPeriodValueTreasuryStockReissued100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents

us-gaap:StockRepurchasedAndRetiredDuringPeriodShares

biib:December2019ShareRepurchaseProgram, us-gaap:CommonStock



Period End2020-03-31
Value3
Percentage of StockRepurchasedAndRetiredDuringPeriodShares100.0

biib:December2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value3
Percentage of StockRepurchasedAndRetiredDuringPeriodShares100.0

biib:March2019ShareRepurchaseProgram, us-gaap:CommonStock



Period End2020-03-31
Value4
Percentage of StockRepurchasedAndRetiredDuringPeriodShares128.1

biib:March2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value4
Percentage of StockRepurchasedAndRetiredDuringPeriodShares128.1

us-gaap:StockholdersEquityOther



Period End2020-03-312018-12-312018-09-302018-06-302018-03-31
Value0-37300479
Percentage of StockholdersEquityOther100.0100.00.00.0100.0

us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital



Period End2020-03-31
Value0
Percentage of StockholdersEquityOther100.0

us-gaap:TranslationAdjustmentForNetInvestmentHedgeNetOfTaxPeriodIncreaseDecrease



Period End2020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value23211114000
Percentage of TranslationAdjustmentForNetInvestmentHedgeNetOfTaxPeriodIncreaseDecrease100.0100.0100.0100.00.00.00.0

us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:NetInvestmentHedging



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value24-20221111-3000
Percentage of TranslationAdjustmentForNetInvestmentHedgeNetOfTaxPeriodIncreaseDecrease105.20.0103.899.184.30.00.00.00.0

us-gaap:ShareRepurchaseProgram

us-gaap:TreasuryStockRetiredCostMethodAmount

biib:December2019ShareRepurchaseProgram



Period End2020-03-31
Value0
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:March2019ShareRepurchaseProgram



Period End2020-03-31
Value0
Percentage of TreasuryStockRetiredCostMethodAmount0.0

us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents

biib:December2019ShareRepurchaseProgram, us-gaap:AdditionalPaidInCapital



Period End2020-03-31
Value15
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:December2019ShareRepurchaseProgram, us-gaap:CommonStock



Period End2020-03-31
Value0
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:December2019ShareRepurchaseProgram, us-gaap:RetainedEarnings



Period End2020-03-31
Value925
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:December2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value-941
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:March2019ShareRepurchaseProgram, us-gaap:AdditionalPaidInCapital



Period End2020-03-31
Value71
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:March2019ShareRepurchaseProgram, us-gaap:CommonStock



Period End2020-03-31
Value0
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:March2019ShareRepurchaseProgram, us-gaap:RetainedEarnings



Period End2020-03-31
Value1208
Percentage of TreasuryStockRetiredCostMethodAmount0.0

biib:March2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value-1279
Percentage of TreasuryStockRetiredCostMethodAmount0.0

us-gaap:ShareRepurchaseProgram

us-gaap:TreasuryStockSharesAcquired

biib:December2019ShareRepurchaseProgram



Period End2020-03-31
Value3
Percentage of TreasuryStockSharesAcquired100.0

biib:March2019ShareRepurchaseProgram



Period End2020-03-31
Value4
Percentage of TreasuryStockSharesAcquired128.1

us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents

biib:December2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value3
Percentage of TreasuryStockSharesAcquired100.0

biib:March2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value4
Percentage of TreasuryStockSharesAcquired128.1

us-gaap:ShareRepurchaseProgram, us-gaap:SubsequentEventType

biib:March2019ShareRepurchaseProgram, us-gaap:SubsequentEvent



Period End2020-04-22
Value4
Percentage of TreasuryStockSharesAcquired0.0

us-gaap:ShareRepurchaseProgram

us-gaap:TreasuryStockValueAcquiredCostMethod

biib:December2019ShareRepurchaseProgram



Period End2020-03-31
Value941
Percentage of TreasuryStockValueAcquiredCostMethod100.0

biib:March2019ShareRepurchaseProgram



Period End2020-03-31
Value1279
Percentage of TreasuryStockValueAcquiredCostMethod135.9

us-gaap:ShareRepurchaseProgram, us-gaap:StatementEquityComponents

biib:December2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value941
Percentage of TreasuryStockValueAcquiredCostMethod100.0

biib:March2019ShareRepurchaseProgram, us-gaap:TreasuryStock



Period End2020-03-31
Value1279
Percentage of TreasuryStockValueAcquiredCostMethod135.9

us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:UnrealizedGainLossOnForeignCurrencyDerivativesNetBeforeTax

us-gaap:NetInvestmentHedging



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value22-4022118
Percentage of UnrealizedGainLossOnForeignCurrencyDerivativesNetBeforeTax100.0100.0100.0100.0100.0

us-gaap:WeightedAverageNumberDilutedSharesOutstandingAdjustment



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
Value0000000000000000001111112223212
Percentage of WeightedAverageNumberDilutedSharesOutstandingAdjustment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveYearsAmortizedCost



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1231731211071351431339777327269255263277281221163185127147125126109796252213029221120819116515214211078207
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterFiveYearsAmortizedCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:AvailableForSaleSecuritiesDebtMaturitiesAfterFiveYearsFairValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1231731221071341431339677327269255263276281221162184127147125126109796252213029221120719116515214211079210
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterFiveYearsFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:Collaborationexpensesaccrual



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value1542811881302162611011561761831801888913031
Percentage of Collaborationexpensesaccrual100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:DuefromantiCD20therapeuticprograms



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value511590582557527526508481553532518502324300305334315314
Percentage of DuefromantiCD20therapeuticprograms100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisition

biib:EstimatedAdditionalPaymentsUponAchievementOfDevelopmentAndCommercialMilestones

biib:BIIB118



Period End2020-03-31
Value635
Percentage of EstimatedAdditionalPaymentsUponAchievementOfDevelopmentAndCommercialMilestones100.0

us-gaap:TypeOfArrangement

biib:SamsungBiosimilarAgreement



Period End2020-03-31
Value210
Percentage of EstimatedAdditionalPaymentsUponAchievementOfDevelopmentAndCommercialMilestones33.1

biib:Inventorynetcurrentandnoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value85880475177677093692694490692510319619591039104910281001933804
Percentage of Inventorynetcurrentandnoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:InvestmentInBiotechnologyCompaniesThatAreDeterminedToBeUnconsolidatedVariableInterestEntities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value22222324112282928284849535347393838291088761110567999121314181722
Percentage of InvestmentInBiotechnologyCompaniesThatAreDeterminedToBeUnconsolidatedVariableInterestEntities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

biib:PlanAssetsForDeferredCompensationFairValueDisclosure

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value24272629292526282828303231343435404038404436353732222116151413161211121513
Percentage of PlanAssetsForDeferredCompensationFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value24272629292526282828303231343435404038404436353732222116151413161211121513
Percentage of PlanAssetsForDeferredCompensationFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

biib:StrategicInvestmentPortfolio

biib:StrategicInvestments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value331393394569104967668754985
Percentage of StrategicInvestmentPortfolio100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:UnrealizedGainLossesOnForeignCurrencyDerivativesNetBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value-340-65-6-4427-3-8-142113-113772649151646123631597241717231611115361636132311
Percentage of UnrealizedGainLossesOnForeignCurrencyDerivativesNetBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

biib:DerivativeMaturity

biib:Shorttermderivative



Period End2020-03-312019-09-302019-06-30
Value-31-59-9
Percentage of UnrealizedGainLossesOnForeignCurrencyDerivativesNetBeforeTax92.491.0155.6

us-gaap:TypeOfArrangement

biib:UpfrontAndMilestonePaymentsMadeToCollaborativePartner

biib:SangamoTherapeuticsInc.Agreement



Period End2020-02-29
Value125
Percentage of UpfrontAndMilestonePaymentsMadeToCollaborativePartner100.0

us-gaap:AccruedIncomeTaxesNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312014-12-312013-12-31
Value801803801801796791786813979142177
Percentage of AccruedIncomeTaxesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccruedRoyaltiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value209220222212195224226218194206190195181195209183161167154161150172173190131160117113424545484347424045
Percentage of AccruedRoyaltiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentAfterTax

us-gaap:NetInvestmentHedging



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value228997
Percentage of AociDerivativeQualifyingAsHedgeExcludedComponentAfterTax100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:AssetsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value276718176195195702211111518242932323725666001311402811910001244
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value43445912606941095938505057774354681364336238522955027533711868526536585776054303301629372787223414271697924665334836273225269226413043256622691857
Percentage of AssetsFairValueDisclosure1573.574841.832807.62327.130454.99769.46043.76211.429883.354517.852866.134405.929422.530253.424547.921150.319927.115620.529591.863288.248645.242565.2398257.1558725.010343.515152.72294.02303.828868.140302.2268783.32692600.02641300.03043800.0213875.0113455.04145.8

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312011-09-302011-06-302010-12-31
Value00000000000000000000121416212321272318202523232020
Percentage of AssetsFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0195.2210.12385.75275.0171.0195.568.581.3155.2225.62100.023500.01925.01030.046.4

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value46205920608742865958510258734424683664446250524455207558714768856568589576304310303429582805225614641730992718337836563251271826633067259022911922
Percentage of AssetsFairValueDisclosure1673.574941.832907.62427.130554.99869.46143.76311.429983.354617.852966.134505.929522.530353.424647.921250.320027.115720.529691.863388.248940.342875.4400742.9564100.010614.515448.22462.52485.129123.340627.8270983.32718100.02663500.03067400.0215900.0114585.04292.2

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value769841002
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

biib:CorporateDebtSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value011100000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax2.616.716.513.310.90.014.314.30.0

biib:CorporateDebtSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value034420000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax7.850.051.653.060.953.871.457.139.1

biib:GovernmentSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value300000000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax44.26.75.54.84.37.70.00.04.3

biib:GovernmentSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value200000000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax32.513.38.810.86.57.70.014.38.7

biib:MortgageAndOtherAssetBackedSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value101100001
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax13.013.317.618.117.430.814.314.347.8

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1601016222
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

biib:CorporateDebtSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value200000000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax13.70.00.00.08.315.013.825.07.1

biib:CorporateDebtSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1100003000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax72.00.025.016.741.765.027.621.40.0

biib:GovernmentSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value000000000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax0.00.08.30.08.36.717.23.625.0

biib:GovernmentSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value000000001
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax1.242.933.333.316.75.020.721.439.3

biib:MortgageAndOtherAssetBackedSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value200000000
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax13.057.133.350.025.08.320.728.628.6

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value2247296538992530303536943288313630115173502643614786540653225901564148913700318820502112204517191245
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

biib:CorporateDebtSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value923105716559339811608127414841039
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis41.135.742.536.932.343.538.747.320.1

biib:CorporateDebtSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value44263310407488528546785611569
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis19.721.426.729.628.123.120.617.930.3

biib:GovernmentSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value3435024352936837067684891075
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis15.317.011.211.622.519.123.415.620.8

biib:GovernmentSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value361510431309237264293339845
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis16.117.211.112.27.87.18.910.816.3

biib:MortgageAndOtherAssetBackedSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value000000000
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis0.00.00.00.00.00.00.00.00.0

biib:MortgageAndOtherAssetBackedSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value175260335244280260274260642
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis7.88.88.69.79.27.18.38.312.4

us-gaap:AvailableForSaleSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value2238297039072538303836893008517250224356478153985328591256444880370031882051211120461720115512456143823171
Percentage of AvailableForSaleSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:EquitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value27633733651090461562448911
Percentage of AvailableForSaleSecurities12.311.48.620.129.816.70.00.00.2

us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

us-gaap:EquitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value6132120294421127132421
Percentage of AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

us-gaap:EquitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1613213784494
Percentage of AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesAmortizedCost

us-gaap:EquitySecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value28621821822948949649649614
Percentage of AvailableForSaleSecuritiesAmortizedCost100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value8461230168611961234123511121064112427302795238125652559281032453023258318201954125113451261930662572351104017411525125712781251119610397746621133
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value8561234169112021237123211111063112327302792237725612552281532553026257518201954125213431262931662573351103017441529126012801251119610407746641143
Percentage of AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value126915602091122716652314204219741809211619611724195725692230243424542122175310866746406757094316202402750113411539489781175944628437447519
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value126715622093122816652313204119741808211519601723195625682231243424542120175310866736406757094316202402750113511549499781176944629437448522
Percentage of AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value223829703907253830383689328631345172
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:AssetBackedSecurities, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value174261337246281260273260643
Percentage of AvailableForSaleSecuritiesDebtSecurities7.88.88.69.79.37.18.38.312.4

us-gaap:CorporateDebtSecurities, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value135316952702168718352459195120452609
Percentage of AvailableForSaleSecuritiesDebtSecurities60.557.169.266.560.466.759.465.350.5

us-gaap:USTreasuryAndGovernment, us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value710101386860492196910608281919
Percentage of AvailableForSaleSecuritiesDebtSecurities31.734.122.223.830.326.332.326.437.1

us-gaap:FairValueByAssetClass, us-gaap:FairValueByMeasurementFrequency

us-gaap:AssetBackedSecurities, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value174261337246281260273260643
Percentage of AvailableForSaleSecuritiesDebtSecurities7.88.88.69.79.37.18.38.312.4

us-gaap:CorporateDebtSecurities, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value135316952702168718352459195120452609
Percentage of AvailableForSaleSecuritiesDebtSecurities60.557.169.266.560.466.759.465.350.5

us-gaap:USTreasuryAndGovernment, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value710101386860492196910608281919
Percentage of AvailableForSaleSecuritiesDebtSecurities31.734.122.223.830.326.332.326.437.1

us-gaap:FinancialInstrument

biib:CorporateDebtSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value921105816579349811607127314841039
Percentage of AvailableForSaleSecuritiesDebtSecurities41.235.642.436.832.343.638.847.420.1

biib:CorporateDebtSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value43163610447538548516775611570
Percentage of AvailableForSaleSecuritiesDebtSecurities19.321.426.729.728.123.120.617.930.4

biib:GovernmentSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value3465034362946837057674891075
Percentage of AvailableForSaleSecuritiesDebtSecurities15.516.911.211.622.519.123.415.620.8

biib:GovernmentSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value363510432310237263293339844
Percentage of AvailableForSaleSecuritiesDebtSecurities16.317.211.112.27.87.28.910.816.3

biib:MortgageAndOtherAssetBackedSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value000000000
Percentage of AvailableForSaleSecuritiesDebtSecurities0.00.00.00.00.00.00.00.00.0

biib:MortgageAndOtherAssetBackedSecuritiesNonCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value174260336245280260273259642
Percentage of AvailableForSaleSecuritiesDebtSecurities7.88.88.69.79.27.18.38.312.4

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value126915622093122816652313204119742115
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value96914081813130913721375124411603057
Percentage of AvailableForSaleSecuritiesDebtSecuritiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:BusinessCombinationContingentConsiderationLiability

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value341346343401421409412499498523522492470467521515508506481495461215213279275280281281293
Percentage of BusinessCombinationContingentConsiderationLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value341346343401421409412499498523522492470467521515508506481495461215213279275280281281293293290280269151
Percentage of BusinessCombinationContingentConsiderationLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.00.00.00.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value1471481471461474443815295248446115805165805705565055044794936426521918529
Percentage of BusinessCombinationContingentConsiderationLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Range, us-gaap:MeasurementInputType

us-gaap:BusinessCombinationContingentConsiderationLiabilityMeasurementInput

srt:Maximum, us-gaap:MeasurementInputDiscountRate



Period End2020-03-31
Value0.0253
Percentage of BusinessCombinationContingentConsiderationLiabilityMeasurementInput100.0

srt:Minimum, us-gaap:MeasurementInputDiscountRate



Period End2020-03-31
Value0.024
Percentage of BusinessCombinationContingentConsiderationLiabilityMeasurementInput94.9

srt:WeightedAverage, us-gaap:MeasurementInputDiscountRate



Period End2020-03-31
Value0.0244
Percentage of BusinessCombinationContingentConsiderationLiabilityMeasurementInput96.4

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value194197196255274265330270273279280265254246251304303301301302397200193243251
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:CashAndCashEquivalentsFairValueDisclosure

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value197425411655112018817051900732377312291184836645203917368748209093804974752716663475236424287261358439309222161399
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value197425411655112018817051900732377312291184836645203917368748209093804974752716663475236424287261358439309222161399
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashEquivalentsAtCarryingValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value197425411655112018817051900732377312291184836645203917368748209093804974752716663475236424287261358439309222161399241440651
Percentage of CashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentType

us-gaap:CommercialPaper



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302011-12-312011-09-302010-12-31
Value121384255338446231125125513012674713184567212138105419521121004016100224
Percentage of CashEquivalentsAtCarryingValue6.215.115.530.223.732.86.617.11.42.510.78.911.11.54.86.50.92.40.64.01.47.62.91.20.80.34.23.90.09.35.34.50.09.20.6

us-gaap:DebtSecurities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value1101591192791681945641161247144133541266102192347947510635434174190401239251358331184128147391183621
Percentage of CashEquivalentsAtCarryingValue5.66.37.224.99.027.63.05.74.320.112.215.98.462.10.625.128.68.712.51.00.95.065.536.780.594.483.596.1100.075.459.557.891.197.876.295.4

us-gaap:MoneyMarketFunds



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value17051628110340510742791695541356194887160551974116005314886733119740427321396
Percentage of CashEquivalentsAtCarryingValue86.464.166.636.257.139.689.274.094.477.173.672.480.536.492.260.859.674.182.076.056.844.893.2

us-gaap:RepurchaseAgreements



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302010-12-31
Value36368176971920232303422204266901341881853083052092944422350067108841483526
Percentage of CashEquivalentsAtCarryingValue1.914.510.78.710.20.01.23.30.00.33.52.70.02.47.611.014.84.919.041.042.631.562.018.75.312.40.00.015.335.237.78.92.214.74.0

biib:FacilityLocation

us-gaap:ConstructionInProgressGross

biib:SolothurnSwitzerland



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-31
Value170019001800180017001600160015001300120096879860948135024799
Percentage of ConstructionInProgressGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ConstructionPayableCurrentAndNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value277849389912519617917815915716111613487
Percentage of ConstructionPayableCurrentAndNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentFairValue



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value66816553649063606155603761116103618864837048700668456808720671107053664566806316466476506596656656666708891155114411491163116011731551113611351113
Percentage of DebtInstrumentFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxAssetsNet



Period End2020-03-312019-12-31
Value31093232
Percentage of DeferredIncomeTaxAssetsNet100.0100.0

us-gaap:DeferredIncomeTaxLiabilitiesNet



Period End2020-03-312019-12-31
Value27222810
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0

us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:DerivativeFairValueOfDerivativeAsset

us-gaap:OtherCurrentAssets, us-gaap:ForeignExchangeContract, us-gaap:NetInvestmentHedging



Period End2020-03-312019-12-312018-12-31
Value2520
Percentage of DerivativeFairValueOfDerivativeAsset100.0100.00.0

us-gaap:BalanceSheetLocation, us-gaap:HedgingDesignation

us-gaap:OtherCurrentAssets, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value7233152811016525271013850221165469
Percentage of DerivativeFairValueOfDerivativeAsset279.21690.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherCurrentAssets, us-gaap:Nondesignated



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value58263144111224
Percentage of DerivativeFairValueOfDerivativeAsset19.7400.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherNoncurrentAssets, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value4070
Percentage of DerivativeFairValueOfDerivativeAsset15.40.00.00.0

us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:DerivativeFairValueOfDerivativeLiability

us-gaap:AccruedLiabilities, us-gaap:InterestRateSwap, us-gaap:FairValueHedging



Period End2020-03-312019-12-312018-12-31
Value020
Percentage of DerivativeFairValueOfDerivativeLiability0.0100.00.0

us-gaap:OtherNoncurrentLiabilities, us-gaap:ForeignExchangeContract, us-gaap:CashFlowHedging



Period End2020-03-312019-12-312018-12-31
Value010
Percentage of DerivativeFairValueOfDerivativeLiability0.073.90.0

us-gaap:BalanceSheetLocation, us-gaap:HedgingDesignation

us-gaap:AccruedLiabilities, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value021566102211484804041114351017
Percentage of DerivativeFairValueOfDerivativeLiability0.087.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccruedLiabilities, us-gaap:Nondesignated



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value22648311131019
Percentage of DerivativeFairValueOfDerivativeLiability0.0104.30.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Currency, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:DerivativeNotionalAmount

currency:CAD, us-gaap:ForeignExchangeContract, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value7402592
Percentage of DerivativeNotionalAmount100.00.0100.0100.0

currency:CHF, us-gaap:ForeignExchangeContract, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value103036131
Percentage of DerivativeNotionalAmount138.40.0147.6142.5

currency:EUR, us-gaap:ForeignExchangeContract, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value2116189219431701
Percentage of DerivativeNotionalAmount2840.80.07774.81845.3

currency:GBP, us-gaap:ForeignExchangeContract, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value186060215
Percentage of DerivativeNotionalAmount249.80.0243.6233.5

currency:JPY, us-gaap:ForeignExchangeContract, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value7902998
Percentage of DerivativeNotionalAmount106.70.0119.2107.2

us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:ForeignExchangeContract, us-gaap:DesignatedAsHedgingInstrument



Period End2020-03-312019-12-312019-09-302018-12-31
Value2559189220962239
Percentage of DerivativeNotionalAmount3435.70.08385.22428.5

us-gaap:HedgingDesignation

us-gaap:Nondesignated



Period End2020-03-312019-12-312019-09-302018-12-31
Value698793848735
Percentage of DerivativeNotionalAmount937.40.03393.6797.3

us-gaap:TypeOfArrangement

us-gaap:DueFromRelatedParties

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-12-312018-12-31
Value385116
Percentage of DueFromRelatedParties100.0100.0100.0

us-gaap:TypeOfArrangement

us-gaap:DueToRelatedPartiesCurrentAndNoncurrent

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-12-312018-12-31
Value1910031
Percentage of DueToRelatedPartiesCurrentAndNoncurrent100.0100.0100.0

us-gaap:EmployeeRelatedLiabilitiesCurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value190309259199160320274209186297241186160282282228180270214214202393323274343134248198156108176144134110159127
Percentage of EmployeeRelatedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:EquityMethodInvestmentOwnershipPercentage

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-12-312019-09-302019-06-302018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312012-02-29
Value0.4990.4990.4990.4990.4990.050.0650.090.090.090.090.10.10.10.10.120.120.120.15
Percentage of EquityMethodInvestmentOwnershipPercentage100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:EquityMethodInvestments

biib:SamsungBiosimilarAgreement



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-02-29
Value651100670800687300712800642680630006136008111560017252002850031700312970049500
Percentage of EquityMethodInvestments100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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
Value4952488148134745467546074688459644894385427641674049393438423742365035613464336632743178307129652848274026302530245124012350229722452212216121112003
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:FiniteLivedIntangibleAssetsByMajorClass

biib:OutLicensedPatents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value49524881542542542542541539537535532529526523519514510506499493487481473465458450443435428421413406398391381370360350306
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization100.0100.011.311.411.611.811.611.712.012.212.512.713.013.313.513.814.014.214.414.714.915.215.415.716.116.516.917.217.517.517.617.717.817.717.617.60.017.50.0

us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsGross

biib:OutLicensedPatents



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value73797379543543543543543543543543543543543543543543543543543543543543543543543578578578578578578578578578578578578
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:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:ForeignCurrencyContractAssetFairValueDisclosure

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value10743161881046635403214446120303027611001687242223151
Percentage of ForeignCurrencyContractAssetFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value10743161881046635403214446120303027611001687242223151
Percentage of ForeignCurrencyContractAssetFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:ForeignCurrencyContractsLiabilityFairValueDisclosure

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value389172424314314711110670131314244614312712569192317514
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value389172424314314711110670131314244614312712569192317514
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass

us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill

us-gaap:InProcessResearchAndDevelopment



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value9569659541175480476480670696680680668653648679692718730735752726314314330330327327327330
Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass, biib:Researchanddevelopmentasset

us-gaap:InProcessResearchAndDevelopment, biib:TGN



Period End2020-03-312018-09-30
Value16141
Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill16.98.7

us-gaap:IntangibleAssetsGrossExcludingGoodwill



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value83998408820684267731772780678257828382648295821881537742771277107662764676457661762772077201721572137214721072094031
Percentage of IntangibleAssetsGrossExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InventoryFinishedGoodsNetOfReserves



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value172174170144108133136158148157175184156170171139144143159175172164140143128108112113115
Percentage of InventoryFinishedGoodsNetOfReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InventoryRawMaterialsNetOfReserves



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value210169159205199196181176164162208148158170166235249213221173139128133124122115112110101
Percentage of InventoryRawMaterialsNetOfReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InventoryWorkInProcessNetOfReserves



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302012-12-31
Value475460421427462606608610594605647629644698712654607577537516513511478447421435389347230
Percentage of InventoryWorkInProcessNetOfReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:InvestmentsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value27671817619519570221111151824293232372566
Percentage of InvestmentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value03293183338845635294190000000000000
Percentage of InvestmentsFairValueDisclosure0.04172.21720.0188.84535.91090.3553.6598.60.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-31
Value276337336510904615624489221111151824293232372566
Percentage of InvestmentsFairValueDisclosure100.04272.21820.0288.84635.91190.3653.6698.6100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:LiabilitiesFairValueDisclosure

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value3891724243143147111106701313142446143127125691923175314500022412
Percentage of LiabilitiesFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel3, us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312011-09-302011-06-302010-12-31
Value3413463434014214094124994985235224924704675215155085064814954612152132792752802812812932932901511258481
Percentage of LiabilitiesFairValueDisclosure9229.74169.93505.12293.11748.11665.91320.51149.2337.2470.4491.6697.03462.53438.23725.72079.41090.83442.21538.01789.23665.13990.73135.33067.01440.31195.31643.34762.79178.12041.05582.730200.06295.0339.8665.6

us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value34535435341844543444354364563462856248448153554055452051252347422022028829430429828629630829528127015112710993
Percentage of LiabilitiesFairValueDisclosure9329.74269.93605.12393.11848.11765.91420.51249.2437.2570.4591.6797.03562.53538.23825.72179.41190.83542.21638.01889.23765.14090.73235.33167.01540.31295.31743.34862.79278.12141.05682.793733.330088.930300.06395.0439.8765.6

us-gaap:NotesPayable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-31
Value5961595459535948594359365931592859325938649464966496649965166524652165066514579583585587589594595597597802105410551055106110611064107010751077
Percentage of NotesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrument

biib:SeniorNotesFivePointTwoPercentDueTwentyFortyFive



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value17231722172217221722172217221722172217221721172117211721172117211721172117210
Percentage of NotesPayable28.928.928.929.029.029.029.029.029.029.026.526.526.526.526.426.426.426.526.40.0

biib:SeniorNotesFourPointZeroFivePercentDueTwentyTwentyFive



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value17391739173917381738173717371737173617361735173517351734173417341733173317330
Percentage of NotesPayable29.229.229.229.229.229.329.329.329.329.226.726.726.726.726.626.626.626.626.60.0

biib:SeniorNotesThreePointSixTwoFivePercentDueTwentyTwentyTwo



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value9969969969969959959959949949949949939939939939929929929910
Percentage of NotesPayable16.716.716.716.716.816.816.816.816.816.715.315.315.315.315.215.215.215.215.20.0

biib:SeniorNotesTwoPointNinePercentDueTwentyTwenty



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value15011495149514911486148014761474147614821486148714831485150015071500148514920
Percentage of NotesPayable25.225.125.125.125.024.924.924.924.925.022.922.922.822.923.023.123.022.822.90.0

us-gaap:DebtInstrument

us-gaap:NotesPayableFairValueDisclosure

biib:SeniorNotesFivePointTwoPercentDueTwentyFortyFive



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value23232107205419531838180218611854189820772030199618901874207019961957175717660
Percentage of NotesPayableFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

biib:SeniorNotesFourPointZeroFivePercentDueTwentyTwentyFive



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value18381897188818671795174517561757178818511867185318121796190818871880176417670
Percentage of NotesPayableFairValueDisclosure79.190.091.995.697.796.894.494.894.289.191.992.895.995.892.294.596.1100.4100.00.0

biib:SeniorNotesThreePointSixTwoFivePercentDueTwentyTwentyTwo



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value1022103810371032102210001001999100710321049105110321026107010611058101410080
Percentage of NotesPayableFairValueDisclosure44.049.350.552.955.655.553.853.953.149.751.752.754.654.851.753.154.157.757.10.0

biib:SeniorNotesTwoPointNinePercentDueTwentyTwenty



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-31
Value14981509150915071500148914911491149015171536153115281521155815611543149715140
Percentage of NotesPayableFairValueDisclosure64.571.673.577.281.682.680.180.478.573.175.676.780.981.275.378.278.985.285.70.0

us-gaap:OperatingLeaseLiabilityNoncurrent



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value4034124104234360
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.00.0

us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:PurchaseCommitmentRemainingMinimumAmountCommitted

biib:DenmarkManufacturingOperations



Period End2020-03-312019-12-312019-09-302019-06-302019-03-31
Value7474114120120
Percentage of PurchaseCommitmentRemainingMinimumAmountCommitted100.0100.0100.0100.0100.0

us-gaap:ValuationAllowancesAndReservesBalance



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312012-12-312011-12-31
Value128111981085106210831051935865859761664724676605538651732662610590584468448474416237155
Percentage of ValuationAllowancesAndReservesBalance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BalanceSheetLocation

us-gaap:AccountsReceivable



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value235197201199175176177162201189197191171166155161156144148143144124119153151
Percentage of ValuationAllowancesAndReservesBalance18.416.518.618.716.216.818.918.823.524.929.726.425.327.628.924.721.421.824.224.424.826.626.632.336.4

us-gaap:OtherCurrentLiabilities



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-31
Value10461001884863907874758702657572467533505438383490575518462446439344329321264
Percentage of ValuationAllowancesAndReservesBalance81.683.581.481.383.883.281.181.276.575.170.373.674.772.471.175.378.678.275.875.675.273.473.467.763.6

us-gaap:ValuationAllowancesAndReservesType

biib:ContractualAdjustments



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312012-12-312011-12-31
Value10961027917905932888767699695606516583552482433534612548500483480371353389335196120
Percentage of ValuationAllowancesAndReservesBalance85.585.784.585.286.084.582.080.980.979.677.780.681.779.780.481.983.682.882.081.882.379.478.882.180.682.777.1

biib:ReserveforCashDiscounts



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-31
Value1451311291241161271261191097156
Percentage of ValuationAllowancesAndReservesBalance11.410.911.911.710.712.213.513.814.411.88.5

us-gaap:SalesReturnsAndAllowances



Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302013-12-312012-12-312011-12-31
Value394039323534414643464546475149586057505148494533332623
Percentage of ValuationAllowancesAndReservesBalance3.13.43.63.13.23.34.45.45.06.06.86.47.08.59.29.08.38.78.28.78.210.510.27.08.111.315.2

Line plots across dimensions of each concept

us-gaap:SharesIssued us-gaap:StatementEquityComponents


us-gaap:Revenues us-gaap:MajorCustomers, us-gaap:TypeOfArrangement


us-gaap:Revenues us-gaap:ProductOrService


us-gaap:NonoperatingIncomeExpense us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents


us-gaap:IncomeTaxExpenseBenefit us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents


us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents


us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents


us-gaap:PaymentsForRepurchaseOfCommonStock us-gaap:ShareRepurchaseProgram