ALXN


Line plots across dimensions of each concept
Line plots across concepts
Tables

Table of contents



us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesAuthorized
us-gaap:StatementEquityComponents
us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfRevenue

us-gaap:CostsAndExpenses

us-gaap:GrossProfit
us-gaap:ConsolidatedEntities
us-gaap:IncomeLossFromContinuingOperationsAttributableToNoncontrollingEntity

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

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

us-gaap:InterestExpense
us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:CounterpartyName, us-gaap:DebtInstrument
us-gaap:InterestExpenseDebt

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

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest
us-gaap:ConsolidatedEntities

us-gaap:OperatingExpenses

us-gaap:OperatingIncomeLoss

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:ProfitLoss
us-gaap:StatementEquityComponents
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
us-gaap:ResearchAndDevelopmentExpense

us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:ProductOrService
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:StatementBusinessSegments
us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments

us-gaap:Revenues

us-gaap:SellingGeneralAndAdministrativeExpense

us-gaap:Assets

us-gaap:Liabilities

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:ConsolidatedEntities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:MarketableSecuritiesCurrent

us-gaap:AccountsReceivableNetCurrent

us-gaap:InventoryNet
us-gaap:BalanceSheetLocation
us-gaap:PublicUtilitiesInventory

us-gaap:InventoryFinishedGoods

us-gaap:OtherAssetsCurrent
us-gaap:ConsolidatedEntities

us-gaap:Land

us-gaap:MachineryAndEquipmentGross

us-gaap:NoncurrentAssets
us-gaap:StatementGeographical

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:FurnitureAndFixturesGross

us-gaap:ConstructionInProgressGross

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AmortizationOfIntangibleAssets

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:Goodwill
us-gaap:BusinessAcquisition
us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass
us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsNet

us-gaap:DeferredTaxAssetsLiabilitiesNet

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherAssetsNoncurrent
us-gaap:ConsolidatedEntities
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquitySecuritiesFvNi

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent

us-gaap:AccountsPayableCurrent
us-gaap:ConsolidatedEntities

us-gaap:AccruedLiabilitiesCurrent
us-gaap:ConsolidatedEntities

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:LiabilitiesCurrent

us-gaap:LongTermDebtCurrent
us-gaap:CounterpartyName, us-gaap:DebtInstrument

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OtherAccruedLiabilitiesCurrent

us-gaap:OtherLiabilitiesCurrent

us-gaap:TaxesPayableCurrent
us-gaap:CounterpartyName, us-gaap:BusinessAcquisition, us-gaap:DebtInstrument
us-gaap:LongTermDebt
us-gaap:CounterpartyName, us-gaap:DebtInstrument
us-gaap:CreditFacility, us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:LongTermDebtNoncurrent
us-gaap:CounterpartyName, us-gaap:DebtInstrument

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:MinorityInterest

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:OperatingLeaseLiability

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValue

us-gaap:MinorityInterest

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:AmortizationOfFinancingCosts

us-gaap:DepreciationDepletionAndAmortization

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInInventories

us-gaap:NetCashProvidedByUsedInOperatingActivities

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

us-gaap:ProfitLoss
us-gaap:StatementEquityComponents

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:RepaymentsOfLongTermDebt

us-gaap:PaymentsForRepurchaseOfCommonStock

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:DeferredTaxAssetsNet

us-gaap:UnrecognizedTaxBenefits

us-gaap:DeferredTaxAssetsValuationAllowance

alxn:AmortizationofIntangibleAssetsAcquired
us-gaap:SubsequentEventType
alxn:AssetAcquisitionConsiderationTransferred

alxn:AssetAcquisitionContingentConsiderationMilestonePayments
us-gaap:BusinessAcquisition
alxn:BusinessCombinationConsiderationTransferredNet
us-gaap:BusinessAcquisition
alxn:BusinessCombinationConsiderationTransferredPerShare
us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType

alxn:BusinessCombinationContingentConsiderationArrangementsExpectedPaymentsNextTwelveMonths
us-gaap:BusinessAcquisition
alxn:BusinessCombinationMergerPayment
us-gaap:StatementScenario, us-gaap:BusinessAcquisition
alxn:BusinessCombinationOwnershipPercentageOfCombinedCompany
dei:LegalEntity, us-gaap:BusinessAcquisition
alxn:BusinessCombinationPaymentIfMergerIsTerminated
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition
alxn:BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCostOfGoodsSold
us-gaap:BusinessAcquisition
alxn:BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibleAssetAmortizationExpense

alxn:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostNotExpensed

alxn:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresTransactionCosts
us-gaap:BusinessAcquisition
alxn:BusinessCombinationTotalConsideration

alxn:CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonths
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonthsConsolidatedPotentialMilestonePayments
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:CollaborationAgreementPotentialFuturePaymentsAdditionalMilestoneAchievement
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:CollaborationAgreementPotentialFuturePaymentsMaximumRegulatoryAndCommercialMilestonePayments
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement
us-gaap:TypeOfArrangement
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:CollaborationAgreementPotentialFuturePaymentsOptionFee
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:CollaborationAgreementPotentialFuturePaymentsUpfrontOptionExercisePayment

alxn:ConsolidationOfNoncontrollingInterestIncludingNoncashExpenseForAcquiredAssets

alxn:EffectiveIncomeTaxRateReconciliationIntangibleAssetImpairmentPercent
us-gaap:BusinessAcquisition, us-gaap:PropertyPlantAndEquipmentByType
alxn:FairValueInputDiscountRate
us-gaap:Range, us-gaap:BusinessAcquisition
us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
alxn:FairValueInputsCostOfDebt

alxn:FairValueInputsWeightedAverageCostOfCapital

alxn:FairValueOfEquitySharesOfBusinessCombination

alxn:NoncashOrPartNoncashAcquisitionContingentConsiderationIssued

alxn:OperatingRightOfUseAssetsExchangedForOperatingLeaseLiability

alxn:ProceedsFromSaleAndMaturityOfDebtSecuritiesAvailableForSaleAndCashEquivalents

alxn:RestructuringChargesAndAccrualAdjustment

alxn:RestructuringChargesEstimatedAdditionalCharge

alxn:RoyaltyAgreementInterestToBeAccrued

alxn:TaxAdjustmentsSettlementsAndUnusualProvisionsNet

us-gaap:BusinessAcquisitionsProFormaNetIncomeLoss

us-gaap:BusinessAcquisitionsProFormaRevenue

us-gaap:BusinessCombinationAcquisitionRelatedCosts
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationConsiderationTransferred1
us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1
us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationIntegrationRelatedCosts
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:ContributionOfProperty
us-gaap:CreditFacility, us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentPeriodicPayment

us-gaap:DeferredIncomeTaxesAndTaxCredits
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsForeign
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquityMethodInvestmentOtherThanTemporaryImpairment
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax

us-gaap:GainLossOnDerivativeInstrumentsNetPretax

us-gaap:GainLossOnDispositionOfAssets1
us-gaap:CounterpartyName
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:HedgingDesignation
us-gaap:GainLossOnFairValueHedgesRecognizedInEarnings

us-gaap:GainLossOnSaleOfPropertyPlantEquipment
us-gaap:BusinessAcquisition
us-gaap:GoodwillPurchaseAccountingAdjustments

us-gaap:ImpairmentOfIntangibleAssetsExcludingGoodwill
us-gaap:IncomeTaxAuthority
us-gaap:IncomeTaxReconciliationTaxCreditsForeign

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements
us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass
us-gaap:IndefinitelivedIntangibleAssetsAcquired

us-gaap:InventoryWriteDown

us-gaap:InvestmentIncomeInvestmentExpense

us-gaap:InvestmentIncomeNet
us-gaap:LitigationCase
us-gaap:LitigationSettlementAmountAwardedToOtherParty
us-gaap:LitigationCase, us-gaap:SubsequentEventType

us-gaap:NoncontrollingInterestIncreaseFromBusinessCombination
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
us-gaap:StatementEquityComponents

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

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:StatementEquityComponents
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax

us-gaap:OtherNoncashIncomeExpense

us-gaap:PaymentsForRestructuring
us-gaap:RestructuringCostAndReserve

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt
us-gaap:BusinessAcquisition
us-gaap:PaymentsToAcquireBusinessesGross

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired

us-gaap:PaymentsToAcquireIntangibleAssets

us-gaap:PaymentsToAcquireOtherInvestments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:PaymentsToAcquireTradingSecuritiesHeldforinvestment

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities

us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
us-gaap:StatementEquityComponents
dei:LegalEntity, us-gaap:CounterpartyName, us-gaap:DebtInstrument
us-gaap:RepaymentsOfDebt
us-gaap:BusinessAcquisition
us-gaap:CounterpartyName, us-gaap:DebtInstrument
us-gaap:CounterpartyName, us-gaap:StatementScenario, us-gaap:DebtInstrument

us-gaap:ResearchAndDevelopmentAssetAcquiredOtherThanThroughBusinessCombinationWrittenOff

us-gaap:RestructuringAndRelatedCostIncurredCost
us-gaap:RestructuringCostAndReserve

us-gaap:RestructuringCharges
us-gaap:RestructuringCostAndReserve

us-gaap:RestructuringCosts

us-gaap:RestructuringReserveAccrualAdjustment1
us-gaap:RestructuringCostAndReserve

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost
us-gaap:BusinessAcquisition

us-gaap:StockIssued1
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesRestrictedStockAwardGross
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:StockIssuedDuringPeriodValueAcquisitions
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockSharesAcquired
us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValueAcquiredCostMethod
us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType
us-gaap:StatementEquityComponents

us-gaap:UnrealizedGainLossOnInvestments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

alxn:AccruedClinicalExpensesPayableCurrent

alxn:AccruedManufacturingPayableCurrent

alxn:AccruedRebatesPayable
us-gaap:CounterpartyName
alxn:AssetSaleContingentPaymentsToBeReceived
us-gaap:BusinessAcquisition
alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLongTermDebt
us-gaap:BusinessAcquisition
alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsInventory
us-gaap:ConsolidatedEntities
alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsAndLiabilitiesNet
us-gaap:BusinessAcquisition
alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherLiabilities
us-gaap:BusinessAcquisition
alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedValidationBatches

alxn:ComputerHardwareAndSoftware

alxn:DeferredTaxAssetsAccruedRoyalties
us-gaap:BusinessAcquisition
alxn:DeferredTaxAssetsLongTermDebt

alxn:DeferredTaxAssetsRightOfUseLeases

alxn:DeferredTaxLiabilitiesInvestmentinPartnerships
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
alxn:DerivativeNotionalAmount1
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
alxn:EquityMethodInvestmentDerecognizedAmount

alxn:GoodwillAccumulatedAmortization
us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass
alxn:IndefiniteLivedIntangibleAssetsGrossExcludingGoodwill

alxn:IntangibleAssetsAccumulatedAmortization

alxn:IntangibleAssetsCost

alxn:InventoryCurrent

alxn:LeaseWeightedAverageDiscountRate

alxn:LesseeLeaseLiability

alxn:LesseeLeaseLiabilityPaymentsDue

alxn:LesseeLeaseLiabilityPaymentsDueAfterYearFive

alxn:LesseeLeaseLiabilityPaymentsDueNextTwelveMonths

alxn:LesseeLeaseLiabilityPaymentsDueYearFive

alxn:LesseeLeaseLiabilityPaymentsDueYearFour

alxn:LesseeLeaseLiabilityPaymentsDueYearThree

alxn:LesseeLeaseLiabilityPaymentsDueYearTwo

alxn:LesseeLeaseLiabilityUndiscountedExcessAmount
us-gaap:IncomeTaxAuthority
alxn:OperatingLossCarryforwardsNotSubjectToExpiration
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
alxn:OtherInvestmentsDerecognizedAmount
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
alxn:ResearchandDevelopmentArrangementPotentialPaymentMaximum
us-gaap:CounterpartyName, us-gaap:BusinessAcquisition, us-gaap:DebtInstrument
alxn:RoyaltyAgreementRemainingRoyaltyPaymentsToBePaid
us-gaap:IncomeTaxAuthority
alxn:TaxCreditCarryforwardNotSubjectToExpiration
us-gaap:IncomeTaxAuthority
alxn:TaxCreditCarryforwardSubjectToExpiration
us-gaap:CounterpartyName
alxn:UnrecordedUnconditionalPurchaseObligationUndiscountedFixedPaymentAmount

us-gaap:AccountsPayableCurrentAndNoncurrent

us-gaap:AccruedRoyaltiesCurrent

us-gaap:BuildingsAndImprovementsGross

us-gaap:BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh

us-gaap:BusinessCombinationContingentConsiderationLiability
us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent
us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent
us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents
us-gaap:ConsolidatedEntities
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets
us-gaap:ConsolidatedEntities
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill
us-gaap:BusinessAcquisition, us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet
us-gaap:ConsolidatedEntities
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets

us-gaap:CapitalizedComputerSoftwareAccumulatedAmortization

us-gaap:CapitalizedComputerSoftwareGross
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:ContractWithCustomerAssetNetCurrent
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentInterestRateEffectivePercentage
us-gaap:CounterpartyName, us-gaap:BusinessAcquisition, us-gaap:DebtInstrument
us-gaap:DebtInstrumentUnamortizedDiscount

us-gaap:DeferredFinanceCostsNet

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredTaxAssetsDerivativeInstruments

us-gaap:DeferredTaxAssetsGoodwillAndIntangibleAssets

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsInProcessResearchAndDevelopment

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition
us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards
us-gaap:BusinessAcquisition

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts
us-gaap:BusinessAcquisition
us-gaap:BusinessAcquisition
us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesLeasingArrangements

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeCollateralObligationToReturnSecurities
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeCollateralRightToReclaimSecurities

us-gaap:DerivativeFairValueOfDerivativeAsset
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:InvestmentType
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral

us-gaap:DerivativeFairValueOfDerivativeLiability
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:InvestmentType
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral
us-gaap:Range, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeFixedInterestRate
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:DerivativeNotionalAmount

us-gaap:EmployeeRelatedLiabilitiesCurrent

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:LitigationCase, us-gaap:SubsequentEventType
us-gaap:EscrowDeposit
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue

us-gaap:FinanceLeaseLiability

us-gaap:FinanceLeaseLiabilityCurrent

us-gaap:FinanceLeaseLiabilityNoncurrent

us-gaap:FinanceLeaseLiabilityPaymentsDue

us-gaap:FinanceLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

us-gaap:FinanceLeaseRightOfUseAsset
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:FiniteLivedIntangibleAssetsGross
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass
us-gaap:ForeignCurrencyContractAssetFairValueDisclosure
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:ForeignCurrencyContractsLiabilityFairValueDisclosure
us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

us-gaap:GoodwillGross

us-gaap:IntangibleAssetsGrossExcludingGoodwill
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass
us-gaap:InterestRateDerivativeAssetsAtFairValue
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass
us-gaap:InterestRateDerivativeLiabilitiesAtFairValue
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass
us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

us-gaap:InventoryRawMaterials

us-gaap:InventoryWorkInProcess
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass
us-gaap:InvestmentsFairValueDisclosure
us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
us-gaap:LitigationCase
us-gaap:LossContingencyEstimateOfPossibleLoss
us-gaap:ConsolidatedEntities
us-gaap:MinorityInterestAmountRepresentedByPreferredStock
us-gaap:Ownership
us-gaap:MinorityInterestOwnershipPercentageByParent

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent
us-gaap:IncomeTaxAuthority
us-gaap:OperatingLossCarryforwards
us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority

us-gaap:RestrictedCashAndCashEquivalentsAtCarryingValue

us-gaap:RestrictedCashAndCashEquivalentsNoncurrent

us-gaap:RestructuringAndRelatedCostExpectedCost1

us-gaap:RestructuringReserve
us-gaap:RestructuringCostAndReserve

us-gaap:RestructuringReserveCurrent

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice

us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
us-gaap:StatementClassOfStock
us-gaap:StockRepurchaseProgramAuthorizedAmount1
us-gaap:SubsequentEventType
us-gaap:StatementClassOfStock
us-gaap:StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType
us-gaap:IncomeTaxAuthority
us-gaap:TaxCreditCarryforwardAmount
us-gaap:StatementGeographical, us-gaap:IncomeTaxAuthority

us-gaap:TradingSecurities

us-gaap:TreasuryStockShares
us-gaap:StatementEquityComponents
us-gaap:CounterpartyName
us-gaap:UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount

Plots across concepts


IncomeStatement
Income Loss From Continuing Operations 
Before Income Taxes Minority Interest And Income Loss From Equity Method Investments
Expenses
Other Nonoperating Income Expense
Balance Sheet
Operating Lease Liability
Assets
Operating Lease Right Of Use Asset
Current Assets
Marketable Securities Current
NonCurrent Assets
Operating Lease Right Of Use Asset
PropertyPlantAndEquipmentNet
Accumulated Depreciation Depletion And Amortization Property Plant And Equipment
Liabilities
Operating Lease Liability
Current Liabilities
Contract With Customer Liability Current
Noncurrent Liabilities
Minority Interest
Stockholders Equity
Accumulated Other Comprehensive Income Loss Net Of Tax
CashFlow
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInOperatingActivities
Increase Decrease In Prepaid Deferred Expense And Other Assets
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Net Cash Provided By Used In Financing Activities
Shares
Treasury Stock Shares
OperatingLeaseLiability
Operating Lease Liability Current
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Payments Due Year Four
InventoryNet
Inventory Finished Goods

Tables

  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CommonStockSharesIssued █▅▂▁242.3240.9239.7239.2NA237.8237.5237.3237.0236.2235.8235.5NA234.3234.0NA233.0232.0231.627231.403231.136230.498229.895229.371202.876201.944NANA199.319197.941197.018196.221195.687194.918194.333192.866186.99185.616NA184.21992.39691.591NANANA
us-gaap:CommonStockSharesAuthorized ▄▄▄▄290.0290.0290.0290.0NA290.0290.0290.0290.0290.0290.0290.0NA290.0290.0NA290.0290.0290.0290.0290.0290.0290.0290.0290.0290.0NANA290.0290.0290.0290.0290.0290.0290.0290.0290.0290.0NA290.0145.0145.0NANANA
 us-gaap:CommonStockSharesOutstanding us-gaap:StatementEquityComponents us-gaap:CommonStock█▇▆▅▅▄▄▄▃▃▂▂▂▁242.3240.9239.7239.2238.9237.8237.5237.3237.0236.2235.8235.5235.2234.3NANANA232.0NANANA230.498NANANA201.944NANANA197.941NANANA194.918NANANA185.616NANANA91.591NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding 222.6NA220.6220.6222.6NA224.5225.6225.5NA224.6222.6223.7NA225.0225.5226.0NA226.088225.756226.873NA226.228204.546202.034NA201.313201.524201.804NA199.711199.299199.057NA201.142197.051194.56NA192.161191.18795.183NANA185.1592.09
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic 220.1NA219.1220.6221.6NA223.3224.2223.8NA222.9222.6222.1NA223.0224.4224.0NA224.18224.089225.06NA226.228202.234199.361NA198.052197.88197.797NA195.662195.247194.771NA193.353188.575185.682NA183.706182.96290.862NANA178.00488.506
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount 0.8NA2.5NA3.2NA3.31.92.6NA2.5NA3.4NA3.96.06.0NA4.524.3453.975NANA2.4352.248NA1.3461.6981.641NA2.0152.2653.007NA0.2261.4891.453NA1.4382.1511.318NANA3.006NA
us-gaap:EarningsPerShareBasic ▇▇▇▁▇█▆▆▇▅▆▃▆▅▅▅▅▅▅▅▅▅▄▅▅▅▆▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅2.892.452.64-4.842.524.022.092.052.63-0.21.48-2.051.120.130.350.740.760.410.420.510.410.3-0.810.840.460.770.90.840.81-0.10.480.490.420.420.480.190.240.260.360.190.30.150.160.120.24
us-gaap:EarningsPerShareDiluted ▇▇▇▁▇█▆▆▇▅▆▃▆▅▅▅▅▅▅▅▅▅▄▅▅▅▆▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅2.862.422.62-4.842.54.02.082.042.61-0.21.47-2.051.110.130.350.730.750.410.420.510.410.29-0.810.830.450.760.880.830.79-0.10.470.480.410.40.460.180.230.250.340.180.280.140.150.120.23
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 TTM Greenblatt ROC _ _███▁█▇▇▇▇▆▇▄▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆636.2622.1684.9-1370.2695.5541.0530.0532.6516.843.7358.6-400.1267.4108.680.0226.7212.0127.0179.306194.706165.84697.314154.568181.082103.707203.695236.659218.849209.503138.072135.275137.691116.972107.876142.71983.70570.03875.3766.19949.02440.23345.03NANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:ComprehensiveIncomeNetOfTax ▇▇▇▁▇█▇▆▇▅▆▃▆▅▅▅▅▅▅▅▅▅▄▅▅▅▆▅▅▅▅▅▅▅▅▅675.4530.4569.8-1077.5522.9870.4477.3422.4577.1-61.6340.7-414.6237.832.455.0115.4146.0169.35477.027111.82233.6874.477-191.845113.242154.027161.617258.681160.48155.776-29.62662.03684.45106.54485.26177.98245.244NANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest -146.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest 528.6NANANA522.9NANANANANANANANANANANANANANANANANANANANANANANANANANANA106.544NA77.98245.24448.79NA82.09329.39319.695NANANANA
us-gaap:CostOfGoodsAndServicesSold ▅█▇▇▄▅▃▃▂▃▃▃▃▇█▂▁125.4152.2144.7144.9111.7114.395.299.285.896.890.695.391.6144.6157.083.669.0NANANANANANANANANANANANA51.55251.358NANA33.147-20.191NANA28.79823.369NANANANANANA
us-gaap:CostOfRevenue ▅█▇▇▄▅▃▃▂▃▃▃▃▇█▂▁125.4152.2144.7144.9111.7114.395.299.285.896.890.695.391.6144.6157.083.669.0NANANANANANANANANANANANA51.55251.358NANA33.147-20.191NANA28.79823.369NANANANANANA
us-gaap:CostsAndExpenses ▂▂▂█▁▂▁▁1000.3969.7903.82814.8749.3843.3733.1670.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:GrossProfit NA1439.61444.01299.71333.11270.01167.91104.11054.61032.0935.9949.7839.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments ███▁███▇█▆▇▄▇▆▆▆▆▆▆▆▆▆▆▆▆▆▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆602.6590.6666.9-1352.1663.6602.0535.5499.5541.8-32.9342.1-418.6351.689.858.0206.3194.0104.323158.114169.965143.59874.546139.359177.292106.945205.341236.209218.646211.911137.977134.288137.263116.741107.269140.76581.72267.80974.07865.67749.08740.826NANA32.08330.073
us-gaap:IncomeTaxExpenseBenefit ▆▅▅▁▆▁▅▅▄▄▄▅▅▅▄▅▅▄▅▅▅▄█▄▄▅▅▅▅▆▅▅▅▅▅▅▅▅▄▄▄113.454.888.8-284.0106.0-287.067.939.7-46.112.111.238.8102.559.5-20.041.124.011.88763.77655.02251.4327.942323.1167.07715.62252.00958.47852.15152.557156.96940.50341.37834.52426.29848.58645.46422.39625.9080.10714.34213.996NANA10.319.139
us-gaap:InterestExpense ███▇█▆▆▆▆▇▇▇▇▇▇▇▇▇▇▇▇▇▆▂▁▁▁▁▁▁▁▁▁▁▁▁▂▁▁▁▁27.127.727.623.625.821.717.918.319.924.524.625.024.125.425.024.824.024.5124.80723.79323.8923.15119.9713.9710.6510.5490.6550.7151.0630.8071.0781.0561.1711.1821.8552.0792.2870.1830.2040.2030.198NANA0.1580.21
 us-gaap:InterestExpenseDebt us-gaap:CounterpartyName,us-gaap:DebtInstrument alxn:HealthCareRoyaltyPartners,alxn:RoyaltyBasedFinancingAgreement▄█▁5.05.14.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▇▇▇▁▇█▆▆▇▅▆▃▆▅▅▅▅▅▅▅▅▅▄▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅636.0535.8578.1-1068.1557.6889.0467.6459.8587.9-45.0330.9-457.4249.130.078.0165.2170.093.094.338114.94392.16666.604-183.757170.21591.323153.332177.731166.495159.354-18.99293.78595.88582.21780.97292.17936.25845.41348.1765.5734.74526.8326.4527.87321.77320.934
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest -146.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:NetIncomeLossAttributableToNoncontrollingInterest us-gaap:ConsolidatedEntities us-gaap:VariableInterestEntityPrimaryBeneficiary-146.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OperatingExpenses NA817.5759.12669.9637.6729.0637.9571.5537.8988.3577.31349.8571.9656.5622.0602.4589.0636.0548.705497.783476.206545.927458.012403.121427.227346.342266.629254.02324.174252.285213.772193.023186.7179.503171.608159.401146.427123.391114.479114.93106.66590.72482.36179.78873.009
us-gaap:OperatingIncomeLoss ███▁█▇▇▇▇▆▇▄▇▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆▆636.2622.1684.9-1370.2695.5541.0530.0532.6516.843.7358.6-400.1267.4108.680.0226.7212.0127.0179.306194.706165.84697.314154.568181.082103.707203.695236.659218.849209.503138.072135.275137.691116.972107.876142.71983.70570.03875.3766.19949.02440.23345.0342.71332.32530.57
us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax █▃▃▃▂▃▅▁52.5-15.4-9.5-11.2-26.5-14.012.2-38.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherNonoperatingIncomeExpense ▂▁▁▁▁█▁▁▂▂▂▁▂▁▁▁▂▁▁0.5-0.7-1.90.2-0.933.00.40.12.42.02.2-1.22.50.3-2.0-0.12.0-1.2-1.0NA0.0NANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss 489.2NANANA557.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ResearchAndDevelopmentExpense us-gaap:CounterpartyName,us-gaap:TypeOfArrangement alxn:CaelumBiosciences,us-gaap:CollaborativeArrangementNA0.03.60.1NA2.60.20.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost ██▇▃▂▆▄▁289.1295.0285.9221.1200.9269.6232.9187.6NANANANANANANANANANANANANANANANANANANANANANANANA3.0NANANANANANANANANANANANA
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ███▇▇▇▆▆▆▆▅▅▅▅▄▅▄▄▄▄▄▄▄▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁1636.51591.81588.71444.61444.81384.31263.11203.31140.41128.81026.51045.0930.9909.7859.1912.7869.6831.0798.524752.546700.425700.867665.791635.983600.333599.476555.146512.495566.616441.909400.405370.091338.941320.526294.136274.719244.733227.559204.047185.699166.126155.976141.569125.834117.578
us-gaap:Revenues ███▇▇▇▆▆▆▆▅▅▅▅▄▅▄▄▄▄▄▄▄▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁1636.51591.81588.71444.61444.81384.31263.11203.31140.41128.81026.51045.0930.9909.7859.1912.7869.6831.0798.524752.546700.425700.867665.791635.983600.333599.476555.146512.495566.616441.909400.405370.091338.941320.526294.136274.719244.733227.559204.047185.699166.126155.976141.569125.834117.578
us-gaap:SellingGeneralAndAdministrativeExpense ▆█▆▅▆▇▅▅▅▆▅▅▅▅▅▅▅▅▄▄▄▄▄▄▃▃▃▃▂▂▂▂▂▂▁▂▁▁▁▁▁342.9444.4334.2301.4319.9381.0299.3299.3281.5318.7258.7277.3257.1296.4271.0265.6262.0259.509230.128231.802232.561241.576212.52221.383187.116183.776157.665159.477129.291134.819122.886123.189108.826112.62489.95794.85587.24286.56777.57278.1865.858NANA56.09850.635
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets █▆▄▁18650.218103.017548.416703.2NA17544.614815.014567.713999.613931.913843.613490.4NA13583.313643.0NA13435.013253.013293.46213029.34712802.44513133.2313153.01513167.7194414.9254201.962NANA3379.6663317.6963049.7952815.2382685.8812613.562505.6082457.612017.4641394.751NA1179.5751154.5291012.037NANANA
us-gaap:Liabilities ▁▇█▁6219.26451.86473.56212.4NA6272.84447.84404.24293.04766.64673.94723.0NA4690.24699.0NA4579.04559.04789.3594830.0084740.1684874.6144900.1464614.848898.023899.944NANA678.688935.617695.029603.698595.828642.71633.173707.916804.184260.259NA226.073253.164152.301NANANA
us-gaap:LiabilitiesAndStockholdersEquity █▆▄▁18650.218103.017548.416703.2NA17544.614815.014567.713999.613931.913843.613490.4NA13583.313643.0NA13435.013253.013293.46213029.34712802.44513133.2313153.01513167.7194414.9254201.962NANA3379.6663317.6963049.7952815.2382685.8812613.562505.6082457.612017.4641394.751NA1179.5751154.5291012.037NANANA
us-gaap:StockholdersEquity █▇▅▄▇▆▄▄▃▂▂▁▂▁▁12416.811651.211074.910490.811747.811271.810367.210163.59706.69165.39169.78767.49112.78893.18944.0NA8856.08694.08504.1038199.3398062.2778258.6168252.8698552.8713516.9023302.018NANA2700.9782382.0792354.7662211.542090.0531970.851872.4351749.6941213.281134.492NA953.502901.365859.736NANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AssetsCurrent █▅▁▃6452.65833.05067.85367.9NA5076.44341.24168.53650.63385.03248.42836.1NA2953.92882.0NA2733.02578.02594.5342361.2092127.5092425.3492480.2192533.2382852.9872796.029NANA2245.882186.8571915.5021678.6331550.0411495.61410.3911276.161811.934941.27NA700.395669.246646.556NANANA
us-gaap:CashAndCashEquivalentsAtCarryingValue █▇▅▆▅▆▅▄▃▃▂▁3429.62964.52268.02825.02315.02685.52171.31984.21544.81365.51228.9727.5NA584.4550.0NA713.0966.0761.989597.55710.1981010.1111163.2811322.123916.814943.999752.164612.045528.285529.857910.411936.4641022.96989.501905.526806.21359.388540.865438.154347.868289.43267.145NA212.104186.062
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents █▇▅▇▅▆▅▄▃▃▃▂▁▁▁▁3506.53034.62328.52872.92355.82723.62203.11984.71546.31367.31231.1732.8513.7586.3550.1541.8NA966.0NANANA1010.1NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:MarketableSecuritiesCurrent █▅▂▁39.734.928.926.8NA64.044.4105.4110.3198.3306.2449.5NA889.7979.0NA749.0327.0550.882582.501317.354374.904295.211172.2291008.2781017.567NANA1029.193984.994392.344NANA0.0NANANA0.0NA20.14159.35494.46NANANA
us-gaap:AccountsReceivableNetCurrent █▄▆▁1473.01409.31437.11372.2NA1243.21116.31123.61016.3922.3910.2853.7NA726.5705.0NA660.0650.0676.837609.297586.249532.832512.253535.824479.883432.888NANA429.021421.752404.956355.284323.907295.598311.369282.722267.397244.288NA212.72200.729168.732NANANA
us-gaap:InventoryNet █▇▇▁912.1862.3861.3577.7NA627.6576.7494.6482.2472.5432.7463.2NA460.4441.0NA396.0375.0363.058329.847293.962289.874236.542234.347174.498176.441NANA126.154102.602105.196112.627101.85694.52190.04994.10892.90681.386NA75.22274.39862.165NANANA
us-gaap:InventoryFinishedGoods ▆██▁489.6510.3510.5422.5NA405.6360.3339.8342.2350.7314.1292.9NA307.1279.0NA203.0215.0153.774152.97114.03591.626112.047113.48582.14154.701NANA45.328.2430.81145.81240.24444.13750.80355.4840.19134.709NA20.06NA20.018NANANA
us-gaap:OtherAssetsCurrent █▅▃▁706.4648.6604.8566.2NA456.1432.5460.7497.0426.4370.4342.2NA292.9207.0NA215.0260.0241.768242.014219.746217.628272.932268.715273.514189.401NANA87.356106.2278.77571.4481.32375.27584.2773.99473.19550.849NA23.58124.86526.911NANANA
us-gaap:Land NA9.6NANANA9.6NANANA9.6NANANA9.6NANANA10.0NANANA9.13NANANA9.13NANANA0.692NANANA0.692NANANA0.692NANANA0.692NANANA
us-gaap:MachineryAndEquipmentGross NA134.1NANANA126.0NANANA161.7NANANA159.2NANANA126.0NANANA91.958NANANA65.079NANANA56.13NANANA49.692NANANA46.021NANANA41.986NANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NoncurrentAssets NA1238.8NANANA1163.3NANANA1471.5NANANA1325.4NANANA1036.0NANANA697.025NANANA392.248NANANA201.109NANANA165.629NANANA165.852NANANA162.24NANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical alxn:OtherCountryNA1.6NANANA0.9NANANA2.1NANANA4.9NANANA8.0NANANA5.269NANANA5.583NANANA4.905NANANA2.622NANANA2.091NANANA1.456NANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical country:USNA261.0NANANA272.8NANANA468.3NANANA455.9NANANA490.0NANANA444.282NANANA298.122NANANA190.791NANANA157.019NANANA157.473NANANA154.227NANANA
 us-gaap:NoncurrentAssets us-gaap:StatementGeographical srt:EuropeNA976.2NANANA889.6NANANA1001.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PropertyPlantAndEquipmentGross NA1513.1NANANA1384.2NANANA1690.8NANANA1485.7NANANA1229.0NANANA873.156NANANA529.903NANANA305.214NANANA245.62NANANA226.459NANANA205.291NANANA
us-gaap:FurnitureAndFixturesGross NA24.9NANANA23.4NANANA27.5NANANA23.8NANANA25.0NANANA15.57NANANA11.371NANANA10.119NANANA8.593NANANA7.163NANANA5.34NANANA
us-gaap:ConstructionInProgressGross NA828.7NANANA734.2NANANA827.1NANANA723.7NANANA495.0NANANA420.034NANANA214.041NANANA41.573NANANA4.996NANANA3.638NANANA3.831NANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment NA274.3NANANA220.9NANANA219.3NANANA160.3NANANA193.0NANANA176.131NANANA137.655NANANA104.105NANANA79.991NANANA60.607NANANA43.051NANANA
us-gaap:AmortizationOfIntangibleAssets ▄▄▄▇▇▇▇███████████████▁54.154.2000000000000354.174.674.775.877.581.280.580.380.280.380.380.280.080.180.079.81282.03580.05580.09779.98736.619NA0.0112.1652.526NANANANANANANANANANANANANANANANANANA
us-gaap:PropertyPlantAndEquipmentNet █▇▄▁1244.81238.81214.51196.4NA1163.31148.01123.51095.71471.51443.41422.6NA1325.41354.0NA1138.01036.0931.06825.301749.295697.025618.733555.388440.487392.248NANA218.086201.109178.842173.721164.966165.629165.047164.568165.763165.852NA163.763160.625162.24NANANA
us-gaap:Goodwill ███▁5100.15100.15100.75075.2NA5037.45037.45037.45037.45037.45037.45037.4NA5037.45037.0NA5037.05037.05037.4445037.4445049.3215047.8855015.5195007.142254.073254.073NANA254.073254.073254.073254.073254.073253.645253.839255.405264.11879.639NA80.03379.11419.954NANANA
 us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass alxn:AcquiredIprd███▁922.0922.0922.0907.0NA0.0NANANANANANANA0.00.0NA31.031.0116.0116.0116.0116.0116.0NANA587.0NANANA598.514NANANA628.25628.25654.55654.5567.55NANANA0.0NANANA
 us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass alxn:PriorityReviewVoucher100.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:IntangibleAssetsNetExcludingGoodwill ███▁3048.33002.43056.62059.7NA3344.33410.13487.63560.83641.33713.63793.8NA3954.44032.0NA4223.04303.04467.7264547.7624627.8174707.9144787.9014824.52587.035587.046NANA603.021609.719646.138643.252644.965646.678648.306675.796677.291.604NA94.01995.29924.146NANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass alxn:KanumaProductLineNA782.7NA820.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass alxn:PurchasedTechnology▇██▁2008.62061.82115.01132.1NA3321.83395.73471.33551.43631.43711.53791.5NA3951.64032.0NA4192.04272.04351.7264431.7624511.8174591.9114671.887NANA0.0NANANA0.0NANANA4.202NANANA4.618NANANA0.0NANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass us-gaap:LicensingAgreements▁▃▆█17.618.519.520.5NA22.314.216.19.29.71.92.1NA2.50.0NA0.00.00.00.00.00.0030.014NANA0.046NANANA9.788NANANA10.53620.05621.24622.6514.009NANANA17.28NANANA
 us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass us-gaap:OtherIntangibleAssets▄▄▄▄0.10.10.10.1NA0.20.20.20.20.20.20.2NA0.3NANANA0.4NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DeferredTaxAssetsLiabilitiesNet NA567.2NANANA208.8NANANANANANANANANANANANANANANANANANANA51.15NANANA-56.439NANANA19.046NANANA122.138NANANA174.213NANANA
us-gaap:OperatingLeaseRightOfUseAsset ▅█▆▁216.8223.1220.1209.9NA204.0206.9209.5192.80.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ▁▃█▂447.0506.2618.2461.7NA429.0671.4541.2462.3396.7400.8400.5NA312.2338.0NA304.0299.0262.698257.631248.503255.057250.643247.431280.343137.627NANA55.2462.54445.49755.82559.85638.05413.51619.2517.89612.518NA5.8475.4014.572NANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:Dicerna█▅▁█21.418.415.021.2NA18.412.013.112.28.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:EidosMember▇█▁▁63.473.228.124.7NA27.817.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:Inozyme▃▁█22.020.525.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:OtherEquitySecurities█▁5.82.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:PortolaPharmaceuticalsNANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:StealthNA2.01.82.5NA4.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName alxn:Zealand▁▆█▄25.429.130.527.5NA28.520.417.414.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent NA1203.3NA861.6NA966.7868.2728.7669.8698.2NANANA710.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AccountsPayableCurrent █▇▁125.3118.689.2NANA74.0NANANANA52.258.8NA70.835.0NA61.064.044.84928.97842.89757.3646.97447.03952.86944.016NANA35.33921.59624.41625.58725.58621.48821.96223.75216.02316.029NA13.4469.02516.026NANANA
us-gaap:AccruedLiabilitiesCurrent ▁█▄910.71084.7978.4NANA892.7NANANANA539.8605.2NA639.4703.0NA546.0508.0485.234407.289359.077403.348357.987407.345308.407395.232NANA196.369402.344255.784188.759186.959249.787247.885270.573206.863186.064NA141.248116.623107.03NANANA
us-gaap:ContractWithCustomerLiabilityCurrent █▁▇█23.83.022.724.7NA6.826.33.13.03.43.23.7NA15.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LiabilitiesCurrent ▅█▄▁1426.21624.71331.01120.1NA1194.31091.21031.5943.81174.01027.41044.4NA952.5972.0NA837.0823.01034.341658.462603.613718.25766.86769.169580.439606.74NANA396.822582.429395.456302.978295.747360.089361.942375.162353.677230.225NA187.78217.182138.515NANANA
us-gaap:LongTermDebtCurrent ██▆▁143.2142.4138.6126.8NA126.7126.6126.6126.593.861.228.5NA167.4167.0NA167.0167.0322.94279.13635.358175.0175.0131.2545.548.0NANA48.048.048.048.048.048.048.048.0108.00.0NANANANANANANA
us-gaap:OperatingLeaseLiabilityCurrent NA28.1NANANA18.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAccruedLiabilitiesCurrent NA143.7NANANA180.4NANANA144.4NANANA158.8NANANA142.0NANANA114.461NANANA76.498NANANA38.177NANANA43.617NANANA24.549NANANA18.623NANANA
us-gaap:OtherLiabilitiesCurrent ▁█▁▂127.0164.1124.8131.7NA100.996.476.249.934.428.431.6NA59.049.0NA22.023.036.06689.63787.86562.0384.33653.15167.04760.655NANA58.25556.68812.8857.7575.4159.5489.0255.1833.9147.92NA17.47915.14911.848NANANA
us-gaap:TaxesPayableCurrent NA150.9NANANA103.9NANANA24.4NANANA30.7NANANA39.0NANANA12.087NANANA94.823NANANA108.907NANANA68.432NANANA18.306NANANA9.58NANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:LongTermDebt us-gaap:CounterpartyName,us-gaap:BusinessAcquisition,us-gaap:DebtInstrument alxn:HealthCareRoyaltyPartners,alxn:PortolaPharmaceuticalsInc,alxn:RoyaltyBasedFinancingAgreementNANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:CounterpartyName,us-gaap:DebtInstrument alxn:HealthCareRoyaltyPartners,alxn:RoyaltyBasedFinancingAgreement█▅▁188.7187.0185.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt us-gaap:CreditFacility,us-gaap:DebtInstrument,us-gaap:LongtermDebtType alxn:SeniorSecuredTermLoan,alxn:CreditAgreement,us-gaap:LineOfCredit▁▃▆█2351.32383.92416.62449.2NA2514.5NANANA2612.52612.52612.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LongTermDebtNoncurrent ▅▆█▁2388.82419.62453.32311.6NA2375.02406.72438.32470.02501.72533.32564.9NA2720.72763.0NA2846.02888.02929.3843171.0923212.7723281.253325.03368.750.09.5NANA45.565.077.089.0101.0101.0113.0180.0247.00.0NANANANANANANA
us-gaap:DeferredIncomeTaxLiabilitiesNet ▁▁▅█1639.11632.21818.21946.8NA2081.4NANANA391.1NANANA365.0NANANA396.0NANANA529.0NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:MinorityInterest 14.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesNoncurrent ▂█▇▁290.8298.8297.1289.8NA265.6280.4269.5267.8155.6129.8132.3NA140.2118.0NA110.090.0131.342124.376107.81873.39382.685217.82375.8153.134NANA45.72247.97352.09442.06336.7822.79218.77812.7599.96911.732NA10.3559.6449.324NANANA
us-gaap:OperatingLeaseLiabilityNoncurrent ▂█▇▁170.8177.1175.8169.4NA164.1166.8165.5150.80.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NA32.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NA25.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NA22.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NA20.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NA103.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquity █▇▅▄▇▆▄▄▃▂▂▁▂▁▁12416.811651.211074.910490.811747.811271.810367.210163.59706.69165.39169.78767.49112.78893.18944.0NA8856.08694.08504.1038199.3398062.2778258.6168252.8698552.8713516.9023302.018NANA2700.9782382.0792354.7662211.542090.0531970.851872.4351749.6941213.281134.492NA953.502901.365859.736NANANA
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest █▁12431.011651.2NANA11747.811271.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AdditionalPaidInCapitalCommonStock █▆▃▁9243.39152.99030.48942.4NA8804.78738.08677.08604.98539.18481.88420.2NA8290.38209.0NA8060.07957.07906.5237852.4327793.0567726.567642.9747659.3112713.052592.167NANA2291.3632106.1832049.2441968.0541899.9871852.2211827.5171782.7571291.5871261.589NA1218.1461195.4141173.48NANANA
us-gaap:RetainedEarningsAccumulatedDeficit █▅▃▁5879.25243.24707.44129.3NA4639.83750.83283.22823.42325.82370.92040.0NA2242.12212.0NA1969.01818.01724.8091387.5041272.5611180.3951113.7911297.5481127.3331036.01NANA538.452379.098398.09304.305208.42126.20345.23-46.948-83.206-128.619NA-242.359-277.104-303.934NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▂▁▁▁▂▃▃▃▄▄▅▄▃▄▄▄▆▆▄▅▅▆▆▆█▆▆▄▄▄▄▅▅▅▅▅▅▅-85.2-124.6-119.2-110.9-101.5-66.8-48.2-57.9-20.5-9.76.9-2.9-45.7-34.4-37.0-13.836.060.0-16.6170.6943.81562.30154.42862.516119.48956.78548.5-32.45-26.435-22.857-12.22319.52630.9626.6352.34516.5427.5564.179NA-19.627-14.275-7.14NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment▆▆▆▆▆▆███████▇▇▇▇▇▆▆▆▆▄▁▃▃▄▄▅▅▆▆▇▇▇▇▇▇-10.2-10.2-9.2-9.2-9.2-9.2-2.6-2.6-2.6-2.6-4.1-4.1-4.1-4.8-7.0-6.4-7.0-7.0-8.364-8.379-7.468-9.589-15.083-24.015-16.822-16.57-14.757-14.187-11.502-11.502-8.394-8.396-5.713-5.712-4.984-4.984-4.183-4.183NANANA-3.018NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest▄▁▂▂▃▄▅▄▆▇█▇▅▆-50.2-102.7-87.3-77.8-66.6-40.1-26.1-38.30.69.633.021.6-29.3-13.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedGainLossNetCashFlowHedgeParentNA-102.7NANANA-40.1NANANA9.6NANANA-13.9NANANA91.9NANANA92.7NANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedTranslationAdjustment▁▅▂▁▁▃▃▄▃▄▂▃▅▄▄▃▂▁▃▃▃▃▃▃▃▅▆▇▇▇█▇▇█████-24.8-11.7-22.7-23.9-25.4-17.4-19.4-16.9-18.4-16.4-21.9-20.2-12.1-15.9-15.0-17.5-21.0-24.0-17.386-17.874-17.999-19.995-19.784-17.937-19.107-13.719-9.826-6.83-6.876-7.382-3.352-4.338-4.258-2.809-2.718-3.702-2.576-2.959NANANA-1.631NANANA
us-gaap:TreasuryStockValue ██▄▁2620.52620.32543.72470.0NA2105.92073.41738.81701.21689.91689.91689.9NA1604.91440.0NA1209.01141.01110.6351041.3141007.178710.663558.347466.527442.99382.964NANA102.42280.36580.36580.36549.33614.2292.6762.6762.6762.676NA2.6762.6762.676NANANA
us-gaap:MinorityInterest 14.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue ▆█▅▄▃▄▃▄▃▂▁▃▂76.085.670.164.157.460.059.160.955.751.444.853.951.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇███▆▆▇▆▆▄▅▁▅▅▅▅▅▅▅▄▄▄▄▄▃▅▅▄▃▄▄▄▃▄▄▄▃▄▃▃▃637.6840.5822.8790.0549.6517.1599.5538.4429.983.4387.1-343.8299.3257.6270.0280.0308.0382.696291.387243.933167.984190.857223.086238.22223.034283.459281.521106.15-31.055208.881144.27597.69646.497104.957141.324101.52762.80590.78776.25278.68424.361NANA45.46221.492
us-gaap:NetCashProvidedByUsedInInvestingActivities ▇▇▅▇▆▇▇▇▇▇▇█▆▇▇▆▆▇▇▆▇▇▇▁▇▇▇▇▇▆▇▇▇▇▇▇▆▇▇▇▇-133.9-80.6-1267.414.5-766.056.3-8.5-41.02.952.2104.7568.3-254.70.7-170.5-253.5-495.0114.558-65.218-330.675-5.665-161.59-195.194-3179.966-48.423-57.179-75.5740.081-90.197-613.271-216.331-191.97-5.569-7.59-6.239-4.559-609.1970.6617.59230.995-72.965NANA-21.644-2.276
us-gaap:NetCashProvidedByUsedInFinancingActivities ▂▂▂▁▂▂▁▂▁▂▂▂▂▁▂▁▂▁▂▂▁▂▂█▂▂▂▂▂▂▂▂▂▂▂▃▃▂▂▂▂-18.7-73.8-107.4-292.5-138.2-59.7-365.9-61.1-252.43.111.07.0-123.5-225.6-95.3-206.7-69.0-283.463-62.187-24.093-466.257-181.31-185.0283346.3415.074-30.112-59.394-22.58119.21224.51644.4646.967-4.308-12.506-36.688350.948364.62212.8538.409-52.10469.892NANA3.47410.736
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect ▇█▁▇▂▇▅▇▅▅▇▅▄▄▄471.9706.1-544.4517.1-367.8520.6218.3438.4179.0138.1498.3219.1-72.634.38.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AmortizationOfFinancingCosts ▁█▁▁1.24.71.21.2NA1.21.31.31.21.31.33.22.32.22.02.32.02.7222.3822.3823.02.1362.513NANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DepreciationDepletionAndAmortization ▄▄▄▄▄▄▄▅▅▅▅▅▅█▅▅▅▅▅▅▅▄▃▁▁▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁75.675.175.289.889.390.692.596.597.298.4104.9100.5101.5185.7109.8102.299.0100.741100.6897.79696.78393.75849.72212.56310.57818.5449.3539.7749.2688.4547.2256.7486.2666.2746.1945.5445.8754.4144.4964.3894.317NANA3.9913.842
us-gaap:IncreaseDecreaseInAccountsReceivable ▇▁▅▄██▃▇▇▃▅▇▅▄▂▅▃▃▆▄▄▄▂▅▅▃▃▃▃▄▅▄▄▃▄▄▄▄▄▃▄87.9-44.145.916.7120.9120.12.7101.195.311.460.494.342.720.2-11.443.43.0-7.87564.65227.93637.28724.86-18.03250.06658.9185.40613.5529.242-0.06318.00743.25428.94626.2327.57123.58221.53320.18426.44616.5649.20826.56NANA6.70717.434
us-gaap:IncreaseDecreaseInInventories ▇▁▅▇▄▇█▅▅▆▄▅▅▆▆▅▆▅▆▆▅█▅▅▅▆▅▅▆▅▅▅▅▅▅▅▅▅▅▅▅59.5-105.3-4.852.4-37.351.081.912.811.241.4-30.88.0-3.919.235.914.119.011.8133.14935.2033.83881.00712.09-2.096-2.62640.595-8.75514.07220.9-5.118-9.3998.9225.4692.798-5.823-0.4569.7461.3161.363-0.87910.379NANA1.02112.755
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇███▆▆▇▆▆▄▅▁▅▅▅▅▅▅▅▄▄▄▄▄▃▅▅▄▃▄▄▄▃▄▄▄▃▄▃▃▃637.6840.5822.8790.0549.6517.1599.5538.4429.983.4387.1-343.8299.3257.6270.0280.0308.0382.696291.387243.933167.984190.857223.086238.22223.034283.459281.521106.15-31.055208.881144.27597.69646.497104.957141.324101.52762.80590.78776.25278.68424.361NANA45.46221.492
us-gaap:NetIncomeLoss ▇▇▇▁▇█▆▆▇▅▆▃▆▅▅▅▅▅▅▅▅▅▄▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅▅636.0535.8578.1-1068.1557.6889.0467.6459.8587.9-45.0330.9-457.4249.130.078.0165.2170.093.094.338114.94392.16666.604-183.757170.21591.323153.332177.731166.495159.354-18.99293.78595.88582.21780.97292.17936.25845.41348.1765.5734.74526.8326.4527.87321.77320.934
us-gaap:ProfitLoss 489.2NANANA557.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ShareBasedCompensation ▇█▇▆▅▆▆▆▅▅▄▅▅▇▅▆▅▄▄▅▅▆▅▆▄▃▃▃▂▂▂▂▂▁▁▁▁▁▁▁▁76.685.570.667.457.660.259.260.956.752.145.753.951.371.157.160.954.040.79146.34147.97956.88966.2851.05667.042.79733.84128.36628.41423.8419.79421.59717.95716.85513.69114.01612.98813.31810.33711.26111.83411.331NANA8.258.104
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▇▇▅▇▆▇▇▇▇▇▇█▆▇▇▆▆▇▇▆▇▇▇▁▇▇▇▇▇▆▇▇▇▇▇▇▆▇▇▇▇-133.9-80.6-1267.414.5-766.056.3-8.5-41.02.952.2104.7568.3-254.70.7-170.5-253.5-495.0114.558-65.218-330.675-5.665-161.59-195.194-3179.966-48.423-57.179-75.5740.081-90.197-613.271-216.331-191.97-5.569-7.59-6.239-4.559-609.1970.6617.59230.995-72.965NANA-21.644-2.276
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▂▆▂▁▂▃▄▄▃▄▄▅▅▇▇█▆█▇▅▅▆▆▆▅▄▂▄▂▁▁▁▁▁▁▁▁▁▁▁▁20.277.510.86.212.230.041.946.836.042.441.262.866.688.393.5100.575.0107.00594.96466.82764.20480.11176.05373.09657.07552.77122.6943.45617.7338.7016.6168.5195.4937.5896.2394.2523.7666.7415.4057.6142.222NANA3.1862.317
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▂▂▂▁▂▂▁▂▁▂▂▂▂▁▂▁▂▁▂▂▁▂▂█▂▂▂▂▂▂▂▂▂▂▂▃▃▂▂▂▂-18.7-73.8-107.4-292.5-138.2-59.7-365.9-61.1-252.43.111.07.0-123.5-225.6-95.3-206.7-69.0-283.463-62.187-24.093-466.257-181.31-185.0283346.3415.074-30.112-59.394-22.58119.21224.51644.4646.967-4.308-12.506-36.688350.948364.62212.8538.409-52.10469.892NANA3.47410.736
us-gaap:RepaymentsOfLongTermDebt ▂▂▂▂▂▂▂▂▁▁▁█▂▂▂▂▂▇▁▁▆▂▁▂▁▁▁▁▂▁▁▁▁▁▃32.632.732.632.732.632.632.732.70.00.00.0250.043.844.043.543.544.0200.00.00.0175.043.750.045.512.012.012.012.019.512.012.012.00.012.067.0NANA0.00.0NANANANANANA
us-gaap:PaymentsForRepurchaseOfCommonStock NA76.573.5253.7107.132.5334.637.611.30.00.00.085.0164.660.1170.968.030.02869.32134.136296.515152.31691.8223.53760.02619.451104.633156.45822.0570.00.031.02935.10711.5530.00.00.0NANANANANANANANA
  2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31

Common Stock Shares Issued

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesIssued


Common
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value242240239239237237237237236235235234234233232231231231230229229202201199197197196195194194192186185184929189
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Authorized

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesAuthorized


Common
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value290290290290290290290290290290290290290290290290290290290290290290290290290290290290290290290290290290145145145
Percentage of CommonStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding us-gaap:StatementEquityComponents

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStock


Common
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value24224023923923823723723723723623523523523423223020119719418591898175
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value2222202202222242252252242222232252252262262252262262042022012012011991991992011971941921919518592
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value2202192202212232242232222222222232242242242242252262021991981971971951951941931881851831829017888
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount


Antidilutive
Period End2021-03-312020-09-302020-03-312019-09-302019-06-302019-03-312018-09-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-06-30
Value800000.02500000.03200000.03300000.01900000.02600000.02500000.03400000.03900000.06000000.06000000.04520000.04345000.03975000.02435000.02248000.01346000.01698000.01641000.02015000.02265000.03007000.0226000.01489000.01453000.01438000.02151000.01318000.03006000.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.892.452.64-4.842.524.022.092.052.63-0.21.48-2.051.120.130.350.740.760.410.420.510.410.3-0.810.840.460.770.90.840.81-0.10.480.490.420.420.480.190.240.260.360.190.30.150.160.120.24
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

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.862.422.62-4.842.54.02.082.042.61-0.21.47-2.051.110.130.350.730.750.410.420.510.410.29-0.810.830.450.760.880.830.79-0.10.470.480.410.40.460.180.230.250.340.180.280.140.150.120.23
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

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value675530569-1077.5522870477422577-61.6340-414.62373255115146169771113374-191.845113154161258160155-29.6266284106857745
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax41.333.335.9-74.636.262.937.835.150.6-5.533.2-39.725.53.66.412.616.820.49.614.94.810.6-28.817.825.727.046.631.327.5-6.715.522.831.426.626.516.5

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest


Comprehensive
Period End2021-03-31
Value-146800000.0
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.0

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest


Comprehensive
Period End2021-03-312020-03-312013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value528522106774548822919
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax32.336.231.426.516.519.940.215.811.9

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfGoodsAndServicesSold


Cost
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312013-12-312013-09-302012-12-312012-09-302011-12-312011-09-30
Value125152144144111114959985969095911441578369515133-20.1912823
Percentage of CostOfGoodsAndServicesSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.79.69.110.07.78.37.58.27.58.68.89.19.815.918.39.27.911.712.810.3-6.912.711.5

Cost Of Revenue

us-gaap:CostOfRevenue

us-gaap:CostOfRevenue


Cost
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312013-12-312013-09-302012-12-312012-09-302011-12-312011-09-30
Value125152144144111114959985969095911441578369515133-20.1912823
Percentage of CostOfRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.79.69.110.07.78.37.58.27.58.68.89.19.815.918.39.27.911.712.810.3-6.912.711.5

Costs And Expenses

us-gaap:CostsAndExpenses

us-gaap:CostsAndExpenses


Costs
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value10009699032814749843733670
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax61.160.956.9194.851.960.958.055.7

Gross Profit

us-gaap:GrossProfit

us-gaap:GrossProfit


Gross
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value143914441299133312701167110410541032935949839
Percentage of GrossProfit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax90.490.990.092.391.792.591.892.591.491.290.990.2

Income Loss From Continuing Operations Attributable To Noncontrolling Entity

us-gaap:IncomeLossFromContinuingOperationsAttributableToNoncontrollingEntity us-gaap:ConsolidatedEntities

us-gaap:IncomeLossFromContinuingOperationsAttributableToNoncontrollingEntity

us-gaap:VariableInterestEntityPrimaryBeneficiary


Income
Period End2021-03-31
Value-196000000.0
Percentage of IncomeLossFromContinuingOperationsAttributableToNoncontrollingEntity100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-12.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments


Income
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value602590666-1352.1663602535499541-32.9342-418.63518958206194104158169143741391771062052362182111371341371161071408167746549403230
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax36.837.142.0-93.645.943.542.441.547.5-2.933.3-40.137.89.96.822.622.312.619.822.620.510.620.927.917.834.342.542.737.431.233.537.134.433.547.929.727.732.632.226.424.625.525.6

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Income
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-23.2-16.3-0.56.81413117.31.4-11.7
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments-3.8-2.40.01.02.72.72.12.1-0.3-3.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.4-1.0-0.00.51.11.11.00.70.1-1.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest196.6326.0-5.359.6130.9149.5165.7221.2-82.489.3

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value1135488-284.0106-287.06739-46.112113810259-20.04124116355517.9423237.077155258525215640413426484522250.1071413109.139
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.93.45.6-19.77.3-20.75.43.3-4.01.11.13.711.06.5-2.34.52.81.48.07.37.31.148.51.12.68.710.510.29.335.510.111.210.28.216.516.59.211.40.17.78.48.27.8

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

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Income
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-5.3-3.5-0.21.63.23.22.61.70.2-2.7
Percentage of IncomeTaxExpenseBenefit-4.7-3.90.11.54.78.1-5.615.20.5-2.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.3-0.2-0.00.10.30.30.20.20.0-0.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest44.970.0-2.114.029.135.237.151.5-11.820.6

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value27272723252117181924242524252524242424232323193.9710.6510.5490.6550.7151.0630.8071.0781.0561.1711.1821.8552.0792.2870.1830.2040.2030.1980.1580.21
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.71.71.71.61.81.61.41.51.72.22.42.42.62.82.92.72.82.93.13.23.43.33.00.60.10.10.10.10.20.20.30.30.30.40.60.80.90.10.10.10.10.10.2

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

us-gaap:InterestRateContract, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Interest
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-11.4-11.6-11.310.0-4.6-0.8-3.4-4.5-4.6-5.1-4.0-3.1-1.4
Percentage of InterestExpense-42.1-41.9-40.942.4-17.8-3.7-19.0-24.6-23.1-20.8-16.3-12.4-5.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.7-0.7-0.70.7-0.3-0.1-0.3-0.4-0.4-0.5-0.4-0.3-0.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:InterestRateContract us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.0

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

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Interest
Period End2021-03-312020-09-302020-03-312019-09-30
Value-11.4-11.3-4.63.4
Percentage of InterestExpense-42.1-40.9-17.819.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.7-0.7-0.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest96.6226.0-40.430.9

Interest Expense Debt

us-gaap:InterestExpenseDebt us-gaap:CounterpartyName, us-gaap:DebtInstrument

us-gaap:InterestExpenseDebt

alxn:HealthCareRoyaltyPartners, alxn:RoyaltyBasedFinancingAgreement


Interest
Period End2021-03-312020-12-312020-09-30
Value5000000.05100000.04900000.0
Percentage of InterestExpenseDebt100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:HealthCareRoyaltyPartners alxn:RoyaltyBasedFinancingAgreement0.00.00.0

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value636535578-1068.1557889467459587-45.0330-457.4249307816517093941149266-183.75717091153177166159-18.992939582809236454865342626272120
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 RevenueFromContractWithCustomerExcludingAssessedTax38.933.736.4-73.938.664.237.038.251.6-4.032.2-43.826.83.39.118.119.511.211.815.313.29.5-27.626.815.225.632.032.528.1-4.323.425.924.325.331.313.218.621.232.118.716.217.019.717.317.8

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

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Net
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-17.9-12.8-0.35.211109.05.61.2-9.0
Percentage of NetIncomeLoss-2.8-2.20.00.92.42.31.51.7-0.3-3.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.1-0.8-0.00.40.90.90.80.50.1-1.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest151.7256.0-3.245.6101.8114.3128.6169.7-70.668.7

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value535578-1068.1889467459587-45.0330-457.4249
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.736.4-73.964.237.038.251.6-4.032.2-43.826.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest


Net
Period End2021-03-31
Value-146800000.0
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.0

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Net
Period End2021-03-31
Value-146800000.0
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Operating Expenses

us-gaap:OperatingExpenses

us-gaap:OperatingExpenses


Operating
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value8177592669637729637571537988577134957165662260258963654849747654545840342734626625432425221319318617917115914612311411410690827973
Percentage of OperatingExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax51.447.8184.844.152.750.547.547.287.656.2129.261.472.272.466.067.776.568.766.168.077.968.863.471.257.848.049.657.257.153.452.255.156.058.358.059.854.256.161.964.258.258.263.462.1

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


Operating
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value636622684-1370.269554153053251643358-400.1267108802262121271791941659715418110320323621820913813513711610714283707566494045423230
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.939.143.1-94.848.139.142.044.345.33.934.9-38.328.711.99.324.824.415.322.525.923.713.923.228.517.334.042.642.737.031.233.837.234.533.748.530.528.633.132.426.424.228.930.225.726.0

Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value52-15.4-9.5-11.2-26.5-14.012-38.9
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.2-1.0-0.6-0.8-1.8-1.01.0-3.2

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-03-31
Value0.5-0.7-1.90.2-0.9330.40.12.42.02.2-1.22.50.3-2.0-0.12.0-1.2-1.00.0
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0-0.0-0.10.0-0.12.40.00.00.20.20.2-0.10.30.0-0.2-0.00.2-0.1-0.10.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-03-312020-03-31
Value489557
Percentage of ProfitLoss100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax29.938.6

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-03-31
Value-146.8
Percentage of ProfitLoss-30.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.0

us-gaap:Parent


Profit
Period End2021-03-312020-03-31
Value636557
Percentage of ProfitLoss130.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.938.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent0.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-03-312020-03-31
Value636557
Percentage of ProfitLoss130.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.938.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.0

Research And Development Expense

us-gaap:ResearchAndDevelopmentExpense us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

us-gaap:ResearchAndDevelopmentExpense

alxn:CaelumBiosciences, us-gaap:CollaborativeArrangement


Research
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-30
Value0.03.60.12.60.20.3
Percentage of ResearchAndDevelopmentExpense0.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.20.00.20.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:CaelumBiosciences us-gaap:CollaborativeArrangement0.00.00.00.00.00.0

Research And Development Expense Excluding Acquired In Process Cost

us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost

us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost


Research
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302013-03-31
Value2892952852212002692321873.0
Percentage of ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.718.518.015.313.919.518.415.60.9

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


Revenue
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value163615911588144414441384126312031140112810261045930909859912869831798752700700665635600599555512566441400370338320294274244227204185166155141125117
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ForeignExchangeForward, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Revenue
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-11.8-11.2-5.09.5119.7119.17.09.73.3-1.7-13.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.7-0.7-0.30.70.80.70.90.80.60.90.3-0.2-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.7-0.7-0.30.70.80.70.90.80.60.90.3-0.2-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ForeignExchangeForward us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ProductOrService

alxn:NetProductSales


Revenue
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value163515911588144414441384126312021140112810261044930
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.099.9100.0100.0100.0100.099.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.099.9100.0100.0100.0100.099.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:NetProductSales100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:OtherRevenue


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value0.80.40.10.20.00.80.20.00.30.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.10.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.10.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:OtherRevenue100.0100.0100.0100.00.0100.0100.00.0100.0100.0

us-gaap:Product


Revenue
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value163515911588144414441384126312021140112810261044930
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.099.9100.0100.0100.0100.099.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.099.9100.0100.0100.0100.099.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Product100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-11.8-5.09.511119.17.03.3-1.7-13.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.7-0.30.70.80.90.80.60.3-0.2-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.7-0.30.70.80.90.80.60.3-0.2-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementBusinessSegments

alxn:AndexxaProductLine


Revenue
Period End2021-03-312020-09-30
Value2838
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.82.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.82.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:AndexxaProductLine100.0100.0

alxn:KanumaProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value342833262826232521191615
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.11.82.31.82.22.22.12.52.02.11.91.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.11.82.31.82.22.22.12.52.02.11.91.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:KanumaProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:Soliris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value102710429751022990980962888898800755813
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax62.865.667.570.878.481.584.486.586.085.987.989.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax62.865.667.570.878.481.584.486.586.085.987.989.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:Soliris100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:StrensiqProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-30
Value1971891841721541411301131251108783
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.111.912.811.912.211.711.411.012.011.910.19.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.111.912.811.912.211.711.411.012.011.910.19.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:StrensiqProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:Ultomiris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3462892512228954240.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.218.217.415.47.14.52.20.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.218.217.415.47.14.52.20.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:Ultomiris100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementGeographical, us-gaap:StatementBusinessSegments

alxn:OtherNonUsExcludingEuropeAndAsiaPacific, alxn:KanumaProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value5.72.08.91.94.82.82.66.11.50.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.10.60.10.40.20.20.60.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.10.60.10.40.20.20.60.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:OtherNonUsExcludingEuropeAndAsiaPacific alxn:KanumaProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:OtherNonUsExcludingEuropeAndAsiaPacific, alxn:Soliris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1201399111612094132123155127
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.38.86.48.09.57.811.712.014.913.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.38.86.48.09.57.811.712.014.913.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:OtherNonUsExcludingEuropeAndAsiaPacific alxn:Soliris100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:OtherNonUsExcludingEuropeAndAsiaPacific, alxn:StrensiqProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value6.44.7106.53.33.53.22.82.51.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.30.70.40.30.30.30.30.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.30.70.40.30.30.30.30.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:OtherNonUsExcludingEuropeAndAsiaPacific alxn:StrensiqProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:OtherNonUsExcludingEuropeAndAsiaPacific, alxn:Ultomiris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value2.92.41.40.40.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.10.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.20.10.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax alxn:OtherNonUsExcludingEuropeAndAsiaPacific alxn:Ultomiris100.0100.0100.0100.00.00.00.00.00.00.0

country:US, alxn:AndexxaProductLine


Revenue
Period End2021-03-312020-09-30
Value2536
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.52.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.52.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US alxn:AndexxaProductLine100.0100.0

country:US, alxn:KanumaProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value17151516161513131311
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.11.11.31.31.21.31.21.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.11.11.31.31.21.31.21.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US alxn:KanumaProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, alxn:Soliris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value553562553556496496463404395336
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.835.438.338.539.341.240.739.437.936.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.835.438.338.539.341.240.739.437.936.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US alxn:Soliris100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, alxn:StrensiqProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value15514914012811810699869989
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.59.49.78.99.38.88.78.49.69.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.59.49.78.99.38.88.78.49.69.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US alxn:StrensiqProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

country:US, alxn:Ultomiris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value2061701581316554240.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.610.710.99.15.24.52.20.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.610.710.99.15.24.52.20.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax country:US alxn:Ultomiris100.0100.0100.0100.0100.0100.0100.00.00.00.0

srt:AsiaPacific, alxn:KanumaProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1.21.10.90.91.31.30.80.81.11.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:AsiaPacific alxn:KanumaProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:AsiaPacific, alxn:Soliris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value102868287118110100989385
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.35.45.76.09.39.28.89.69.09.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.35.45.76.09.39.28.89.69.09.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:AsiaPacific alxn:Soliris100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:AsiaPacific, alxn:StrensiqProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1716151314129.97.26.35.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.00.91.11.00.90.70.60.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.01.01.00.91.11.00.90.70.60.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:AsiaPacific alxn:StrensiqProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:AsiaPacific, alxn:Ultomiris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value736959573.70.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.54.44.14.00.30.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.54.44.14.00.30.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:AsiaPacific alxn:Ultomiris100.0100.0100.0100.0100.00.00.00.00.00.0

srt:Europe, alxn:AndexxaProductLine


Revenue
Period End2021-03-312020-09-30
Value3.62.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Europe alxn:AndexxaProductLine100.0100.0

srt:Europe, alxn:KanumaProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value109.58.47.56.36.86.34.75.85.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.70.60.60.50.50.60.60.50.60.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.70.60.60.50.50.60.60.50.60.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Europe alxn:KanumaProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:Europe, alxn:Soliris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value251254247263255280264262253250
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.416.017.218.220.223.323.225.524.226.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax15.416.017.218.220.223.323.225.524.226.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Europe alxn:Soliris100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:Europe, alxn:StrensiqProductLine


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value18191824191917161614
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.21.21.31.71.51.61.51.61.61.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.21.21.31.71.51.61.51.61.61.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Europe alxn:StrensiqProductLine100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:Europe, alxn:Ultomiris


Revenue
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value63463233210.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.92.92.22.31.70.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.92.92.22.31.70.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:Europe alxn:Ultomiris100.0100.0100.0100.0100.00.00.00.00.00.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value163615911588144414441384126312031140112810261045930909859912869831798752700700665635600599555512566441400370338320294274244227204185166155141125117
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 RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Selling General And Administrative Expense

us-gaap:SellingGeneralAndAdministrativeExpense

us-gaap:SellingGeneralAndAdministrativeExpense


Selling
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value342444334301319381299299281318258277257296271265262259230231232241212221187183157159129134122123108112899487867778655650
Percentage of SellingGeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax21.027.921.020.922.127.523.724.924.728.225.226.527.632.631.529.130.131.228.830.833.234.531.934.831.230.728.431.122.830.530.733.332.135.130.634.535.638.038.042.139.644.643.1

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value186501810317548167031754414815145671399913931138431349013583136431343513253132931302912802131331315313167441442013379331730492815268526132505245720171394117911541012786
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities

us-gaap:Liabilities


Liabilities
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value62196451647362126272444744044293476646734723469046994579455947894830474048744900461489889967893569560359564263370780426022625315298
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets33.335.636.937.235.830.030.230.734.233.835.034.534.434.134.436.037.137.037.137.335.020.321.420.128.222.821.422.224.625.328.839.918.719.221.915.012.5

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value186501810317548167031754414815145671399913931138431349013583136431343513253132931302912802131331315313167441442013379331730492815268526132505245720171394117911541012786
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value1241611651110741049011747112711036710163970691659169876791128893894488568694850481998062825882528552351633022700238223542211209019701872174912131134953901859688247101
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets66.664.463.162.80.064.270.069.869.365.866.265.00.065.565.665.965.664.062.963.062.962.765.079.778.679.971.877.278.677.875.474.771.260.181.380.878.185.087.50.00.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312010-12-312009-12-312008-12-312007-12-31
Value-124.6-119.2-110.9-101.5-66.8-48.2-57.9-20.5-9.76.9-2.9-45.7-34.4606256-24.0-7.14-1.9422.947-1.443
Percentage of StockholdersEquity-1.1-1.1-1.1-0.9-0.6-0.5-0.6-0.2-0.10.1-0.0-0.5-0.40.70.81.7-1.0-0.8-0.31.2-1.4
Percentage of Assets-0.7-0.7-0.70.0-0.4-0.3-0.4-0.1-0.10.0-0.00.0-0.30.50.51.3-0.7-0.7-0.20.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value915290308942886488048738867786048539848184208350829079577726259221061852126111731093941833
Percentage of StockholdersEquity78.681.585.275.578.184.385.488.693.292.596.091.693.291.593.678.588.494.0111.2136.5158.9381.1820.9
Percentage of Assets50.651.553.50.050.259.059.661.561.361.362.40.061.060.058.861.763.570.990.5116.0139.10.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value5243470741295197463937503283282323252370204024972242181811801036379126-128.619-303.934-400.964-696.13-729.279
Percentage of StockholdersEquity45.042.539.444.241.236.232.329.125.425.923.327.425.220.914.331.415.96.4-11.3-35.4-58.2-281.8-718.2
Percentage of Assets29.026.824.70.026.425.322.520.216.717.115.10.016.513.79.024.711.44.8-9.2-30.0-51.00.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2620.3-2543.7-2470.0-2213.0-2105.9-2073.4-1738.8-1701.2-1689.9-1689.9-1689.9-1689.9-1604.9-1141.0-710.663-382.964-80.365-14.229-2.676-2.676-2.676-1.26-1.26
Percentage of StockholdersEquity-22.5-23.0-23.5-18.8-18.7-20.0-17.1-17.5-18.4-18.4-19.3-18.5-18.0-13.1-8.6-11.6-3.4-0.7-0.2-0.3-0.4-0.5-1.2
Percentage of Assets-14.5-14.5-14.80.0-12.0-14.0-11.9-12.2-12.1-12.2-12.50.0-11.8-8.6-5.4-9.1-2.4-0.5-0.2-0.3-0.30.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value6452583350675367507643414168365033853248283629532882273325782594236121272425248025332852279622452186191516781550149514101276811941700669646373
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets34.632.228.932.128.929.328.626.124.323.521.021.721.120.319.519.518.116.618.518.919.264.666.566.565.962.859.657.757.256.351.940.267.559.458.063.947.5

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-06-302010-03-312009-12-312008-12-312007-12-31
Value34292964226828252315268521711984154413651228727584550713966761597710101011631322916943752612528529910936102298990580635954043834728926721218615713895
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets18.416.412.916.90.015.314.713.611.09.88.95.44.34.05.37.35.74.65.57.78.810.020.822.50.00.015.616.029.933.338.137.936.132.817.838.80.029.525.126.40.00.020.00.00.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Cash
Period End2021-03-31
Value56
Percentage of CashAndCashEquivalentsAtCarryingValue1.6
Percentage of Assets0.3
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-312015-12-31
Value350630342328287223552723220319841546136712317325135865505419661010
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets18.816.813.317.20.015.514.913.611.09.88.95.40.04.34.00.07.37.7

Marketable Securities Current

us-gaap:MarketableSecuritiesCurrent

us-gaap:MarketableSecuritiesCurrent


Marketable
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302012-12-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value3934282664441051101983064498899797493275505823173742951721008101710299843920.00.020599419
Percentage of MarketableSecuritiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.20.40.30.70.81.42.23.36.57.25.62.54.14.52.52.92.21.322.824.230.529.712.90.00.01.75.19.32.4

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

us-gaap:AccountsReceivableNetCurrent


Accounts
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value14731409143713721243111611231016922910853726705660650676609586532512535479432429421404355323295311282267244212200168113
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.97.88.28.27.17.57.77.36.66.66.35.35.24.94.95.14.74.64.13.94.110.910.312.712.713.312.612.111.312.411.513.317.518.017.416.714.5

Inventory Net

us-gaap:InventoryNet

us-gaap:InventoryNet


Inventory
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value912862861577627576494482472432463460441396375363329293289236234174176126102105112101949094928175746240
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 Assets4.94.84.93.53.63.93.43.43.43.13.43.43.22.92.82.72.52.32.21.81.84.04.23.73.13.44.03.83.63.63.84.65.86.46.46.15.2

us-gaap:InventoryNet us-gaap:BalanceSheetLocation

us-gaap:Inventories


Inventory
Period End2021-03-312020-12-312020-09-302019-12-31
Value803775729627
Percentage of InventoryNet88.190.084.6100.0
Percentage of Assets4.34.34.23.6
Percentage of Assets us-gaap:Inventories0.00.00.00.0

us-gaap:OtherAssets


Inventory
Period End2021-03-312020-12-312020-09-30
Value10886132
Percentage of InventoryNet11.910.015.4
Percentage of Assets0.60.50.8
Percentage of Assets us-gaap:OtherAssets0.00.00.0

us-gaap:InventoryNet us-gaap:PublicUtilitiesInventory

alxn:PreApprovalInventory


Inventory
Period End2021-03-312020-12-312020-09-302020-06-302019-12-31
Value86391177660
Percentage of InventoryNet9.44.613.613.39.6
Percentage of Assets0.50.20.70.50.3
Percentage of Assets alxn:PreApprovalInventory0.00.00.00.00.0

Inventory Finished Goods

us-gaap:InventoryFinishedGoods

us-gaap:InventoryFinishedGoods


Inventory
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302010-12-31
Value489510510422405360339342350314292307279203215153152114911121138254452830454044505540342020
Percentage of InventoryFinishedGoods100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.62.82.92.52.32.42.32.42.52.32.22.32.01.51.61.21.20.90.70.90.91.91.31.30.91.01.61.51.72.02.32.02.51.72.0

Other Assets Current

us-gaap:OtherAssetsCurrent

us-gaap:OtherAssetsCurrent


Other
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value70664860456645643246049742637034229220721526024124221921727226827318987106787181758473735023242620
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.83.63.43.42.62.93.23.63.12.72.52.21.51.62.01.81.91.71.72.12.06.24.52.63.22.62.53.02.93.43.03.63.62.02.22.72.6

us-gaap:OtherAssetsCurrent us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Other
Period End2021-03-31
Value8.6
Percentage of OtherAssetsCurrent1.2
Percentage of Assets0.0
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Land

us-gaap:Land

us-gaap:Land


Land
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value9600000.09600000.09600000.09600000.010000000.09130000.09130000.0692000.0692000.0692000.0692000.0
Percentage of Land100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.10.10.20.00.00.00.1

Machinery And Equipment Gross

us-gaap:MachineryAndEquipmentGross

us-gaap:MachineryAndEquipmentGross


Machinery
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value134126161159126916556494641
Percentage of MachineryAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.71.21.21.00.71.51.71.93.34.1

Noncurrent Assets

us-gaap:NoncurrentAssets

us-gaap:NoncurrentAssets


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value12381163147113251036697392201165165162
Percentage of NoncurrentAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.86.610.69.87.85.39.36.16.311.916.0

us-gaap:NoncurrentAssets us-gaap:StatementGeographical

alxn:OtherCountry


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value1.60.92.14.98.05.2695.5834.9052.6222.0911.456
Percentage of NoncurrentAssets0.10.10.10.40.80.81.42.41.61.30.9
Percentage of Assets0.00.00.00.00.10.00.10.10.10.10.1
Percentage of Assets alxn:OtherCountry0.00.00.00.00.00.00.00.00.00.00.0

country:US


Noncurrent
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value261272468455490444298190157157154
Percentage of NoncurrentAssets21.123.531.834.447.363.776.094.994.894.995.1
Percentage of Assets1.41.63.43.43.73.47.15.86.011.315.2
Percentage of Assets country:US0.00.00.00.00.00.00.00.00.00.00.0

srt:Europe


Noncurrent
Period End2020-12-312019-12-312018-12-31
Value9768891001
Percentage of NoncurrentAssets78.876.568.0
Percentage of Assets5.45.17.2
Percentage of Assets srt:Europe0.00.00.0

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value15131384169014851229873529305245226205
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.47.912.110.99.36.612.69.29.416.220.3

Furniture And Fixtures Gross

us-gaap:FurnitureAndFixturesGross

us-gaap:FurnitureAndFixturesGross


Furniture
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value24232723251511108.5937.1635.34
Percentage of FurnitureAndFixturesGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.20.20.20.10.30.30.30.50.5

Construction In Progress Gross

us-gaap:ConstructionInProgressGross

us-gaap:ConstructionInProgressGross


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value828734827723495420214414.9963.6383.831
Percentage of ConstructionInProgressGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.64.25.95.33.73.25.11.30.20.30.4

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value274220219160193176137104796043
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.31.61.21.51.33.33.13.14.34.3

Amortization Of Intangible Assets

us-gaap:AmortizationOfIntangibleAssets

us-gaap:AmortizationOfIntangibleAssets


Amortization
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-03-312014-12-312014-09-30
Value54545474747577818080808080808080807982808079360.0112.1652.526
Percentage of AmortizationOfIntangibleAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value124412381214119611631148112310951471144314221325135411381036931825749697618555440392218201178173164165165164165165163160162164
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.76.86.97.26.67.77.77.810.610.410.59.89.98.57.87.06.35.95.34.74.210.09.36.56.15.96.26.16.36.66.78.211.913.913.916.020.9

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value5100510051005075503750375037503750375037503750375037503750375037503750495047501550072542542542542542542542532532552647980791919
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets27.328.229.130.428.734.034.636.036.236.437.337.136.937.538.037.938.739.438.438.138.05.86.07.57.78.39.09.59.710.110.413.15.76.86.92.02.5

us-gaap:Goodwill us-gaap:BusinessAcquisition

alxn:PortolaPharmaceuticalsInc


Goodwillus-gaap:
Period End2020-07-02
Value25
Percentage of Goodwill0.0
Percentage of Assets0.0
Percentage of Assets alxn:PortolaPharmaceuticalsInc0.0

Indefinite Lived Intangible Assets Excluding Goodwill

us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass

us-gaap:IndefiniteLivedIntangibleAssetsExcludingGoodwill

alxn:AcquiredIprd


Indefinite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value9229229229070.00.00.03131116116116116116587598628628654654670.0
Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets4.95.15.35.40.00.00.00.20.20.90.90.90.90.914.018.024.025.126.632.44.80.0
Percentage of Assets alxn:AcquiredIprd0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

alxn:PriorityReviewVoucher


Indefinite
Period End2021-03-31
Value100
Percentage of IndefiniteLivedIntangibleAssetsExcludingGoodwill10.8
Percentage of Assets0.5
Percentage of Assets alxn:PriorityReviewVoucher0.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill


Intangible
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value3048300230562059334434103487356036413713379339544032422343034467454746274707478748245875876036096466436446466486756779194952428
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets16.316.617.412.319.123.023.925.426.126.828.129.129.631.432.533.634.936.135.836.436.613.314.017.818.421.222.824.024.725.927.533.66.68.08.32.43.6

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsNet

alxn:KanumaProductLine


Finite
Period End2020-12-312020-06-30
Value782820
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0
Percentage of Assets4.34.9
Percentage of Assets alxn:KanumaProductLine0.00.0

alxn:PurchasedTechnology


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value200820612115113233213395347135513631371137913951403241924272435144314511459146710.00.04.2024.6180.0
Percentage of FiniteLivedIntangibleAssetsNet0.0263.40.0138.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets10.811.412.16.818.922.923.825.426.126.828.129.129.631.232.232.734.035.235.035.50.00.00.20.30.0
Percentage of Assets alxn:PurchasedTechnology0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LicensingAgreements


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value171819202214169.29.71.92.12.50.00.00.00.00.00.00.0030.0140.0469.788102021221417
Percentage of FiniteLivedIntangibleAssetsNet0.02.40.02.50.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets0.10.10.10.10.10.10.10.10.10.00.00.00.00.00.00.00.00.00.00.00.00.30.40.80.91.11.01.7
Percentage of Assets us-gaap:LicensingAgreements0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherIntangibleAssets


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-31
Value0.10.10.10.10.20.20.20.20.20.20.20.30.4
Percentage of FiniteLivedIntangibleAssetsNet0.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:OtherIntangibleAssets0.00.00.00.00.00.00.00.00.00.00.00.00.0

Deferred Tax Assets Liabilities Net

us-gaap:DeferredTaxAssetsLiabilitiesNet

us-gaap:DeferredTaxAssetsLiabilitiesNet


Deferred
Period End2020-12-312019-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value56720851-56.43919122174
Percentage of DeferredTaxAssetsLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.11.21.2-1.70.78.817.2

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value2162232202092042062091920.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets1.21.21.31.31.21.41.41.40.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value447506618461429671541462396400400312338304299262257248255250247280137556245555938131917125.8475.4014.5725.403
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.42.83.52.82.44.53.73.32.82.93.02.32.52.32.32.02.01.91.91.91.96.33.31.61.91.52.02.21.50.50.80.90.90.50.50.50.7

us-gaap:OtherAssetsNoncurrent us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Other
Period End2021-03-31
Value7.8
Percentage of OtherAssetsNoncurrent1.7
Percentage of Assets0.0
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Equity Securities Fv Ni

us-gaap:EquitySecuritiesFvNi us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:EquitySecuritiesFvNi

alxn:Dicerna


Equity
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value21181521181213128.9
Percentage of EquitySecuritiesFvNi100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.10.10.10.10.1
Percentage of Assets alxn:Dicerna0.00.00.00.00.00.00.00.00.0

alxn:EidosMember


Equity
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-30
Value637328242717
Percentage of EquitySecuritiesFvNi296.3397.8187.3116.5151.1141.7
Percentage of Assets0.30.40.20.10.20.1
Percentage of Assets alxn:EidosMember0.00.00.00.00.00.0

alxn:Inozyme


Equity
Period End2021-03-312020-12-312020-09-30
Value222025
Percentage of EquitySecuritiesFvNi102.8111.4166.7
Percentage of Assets0.10.10.1
Percentage of Assets alxn:Inozyme0.00.00.0

alxn:OtherEquitySecurities


Equity
Period End2021-03-312020-12-31
Value5.82.6
Percentage of EquitySecuritiesFvNi27.114.1
Percentage of Assets0.00.0
Percentage of Assets alxn:OtherEquitySecurities0.00.0

alxn:PortolaPharmaceuticals


Equity
Period End2020-07-02
Value47
Percentage of EquitySecuritiesFvNi0.0
Percentage of Assets0.0
Percentage of Assets alxn:PortolaPharmaceuticals0.0

alxn:Stealth


Equity
Period End2020-12-312020-09-302020-06-302019-12-31
Value2.01.82.54.4
Percentage of EquitySecuritiesFvNi10.912.011.823.9
Percentage of Assets0.00.00.00.0
Percentage of Assets alxn:Stealth0.00.00.00.0

alxn:Zealand


Equity
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-31
Value2529302728201714
Percentage of EquitySecuritiesFvNi118.7158.2203.3129.7154.9170.0132.8118.9
Percentage of Assets0.10.20.20.20.20.10.10.1
Percentage of Assets alxn:Zealand0.00.00.00.00.00.00.00.0

Accounts Payable And Accrued Liabilities Current

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent

us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent


Accounts
Period End2020-12-312020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value1203861966868728669698710
Percentage of AccountsPayableAndAccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.65.25.55.95.04.85.05.2

Accounts Payable Current

us-gaap:AccountsPayableCurrent

us-gaap:AccountsPayableCurrent


Accounts
Period End2021-03-312020-12-312020-09-302019-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value1251188974525870356164442842574647524435212425252121231616139.0251611
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.70.50.40.40.40.50.30.50.50.30.20.30.40.40.41.21.01.00.70.80.91.00.80.91.00.81.11.10.81.61.5

us-gaap:AccountsPayableCurrent us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Accounts
Period End2021-03-31
Value3.6
Percentage of AccountsPayableCurrent2.9
Percentage of Assets0.0
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Accrued Liabilities Current

us-gaap:AccruedLiabilitiesCurrent

us-gaap:AccruedLiabilitiesCurrent


Accrued
Period End2021-03-312020-12-312020-09-302019-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value910108497889253960563970354650848540735940335740730839519640225518818624924727020618614111610766
Percentage of AccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.96.05.65.13.94.54.75.24.13.83.73.12.83.12.73.17.09.45.812.18.46.77.09.69.911.010.313.312.010.110.68.5

us-gaap:AccruedLiabilitiesCurrent us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Accrued
Period End2021-03-31
Value2.3
Percentage of AccruedLiabilitiesCurrent0.3
Percentage of Assets0.0
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.0

Contract With Customer Liability Current

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:ContractWithCustomerLiabilityCurrent


Contract
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value233.022246.8263.13.03.43.23.715
Percentage of ContractWithCustomerLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.00.10.10.00.20.00.00.00.00.00.1

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value1426162413311120119410911031943117410271044952972837823103465860371876676958060639658239530229536036137535323018721713885
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.69.07.66.76.87.47.16.78.47.47.77.07.16.26.27.85.14.75.55.85.813.114.411.717.613.010.811.013.814.415.317.516.515.918.813.710.8

Long Term Debt Current

us-gaap:LongTermDebtCurrent

us-gaap:LongTermDebtCurrent


Long
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value1431421381261261261261269361281671671671673227935175175131454848484848484848481080.0
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets0.80.80.80.80.70.90.90.90.70.40.21.21.21.21.32.40.60.31.31.31.01.01.11.41.41.61.71.81.81.92.05.40.0

us-gaap:LongTermDebtCurrent us-gaap:CounterpartyName, us-gaap:DebtInstrument

alxn:HealthCareRoyaltyPartners, alxn:RoyaltyBasedFinancingAgreement


Long
Period End2021-03-312020-12-312020-09-30
Value161511
Percentage of LongTermDebtCurrent11.410.98.4
Percentage of Assets0.10.10.1
Percentage of Assets alxn:HealthCareRoyaltyPartners alxn:RoyaltyBasedFinancingAgreement0.00.00.0

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OperatingLeaseLiabilityCurrent


Operating
Period End2020-12-312019-12-31
Value2818
Percentage of OperatingLeaseLiabilityCurrent100.0100.0
Percentage of Assets0.20.1

Other Accrued Liabilities Current

us-gaap:OtherAccruedLiabilitiesCurrent

us-gaap:OtherAccruedLiabilitiesCurrent


Other
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value1431801441581421147638432418
Percentage of OtherAccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.81.01.01.21.10.91.81.21.71.81.8

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent

us-gaap:OtherLiabilitiesCurrent


Other
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value12716412413110096764934283159492223368987624.3365367605856127.7575.4159.5489.0255.1833.9147.921715114.743
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.90.70.80.60.70.50.40.20.20.20.40.40.20.20.30.70.70.50.00.41.51.41.71.70.40.30.20.40.40.20.20.61.51.31.20.6

Taxes Payable Current

us-gaap:TaxesPayableCurrent

us-gaap:TaxesPayableCurrent


Taxes
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value150103243039129410868189.58
Percentage of TaxesPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.80.60.20.20.30.12.33.32.61.30.9

Long Term Debt

us-gaap:LongTermDebt us-gaap:CounterpartyName, us-gaap:BusinessAcquisition, us-gaap:DebtInstrument

us-gaap:LongTermDebt

alxn:HealthCareRoyaltyPartners, alxn:PortolaPharmaceuticalsInc, alxn:RoyaltyBasedFinancingAgreement


Long
Period End2020-07-02
Value182
Percentage of LongTermDebt100.0
Percentage of Assets0.0
Percentage of Assets alxn:HealthCareRoyaltyPartners alxn:PortolaPharmaceuticalsInc alxn:RoyaltyBasedFinancingAgreement0.0

us-gaap:LongTermDebt us-gaap:CounterpartyName, us-gaap:DebtInstrument

alxn:HealthCareRoyaltyPartners, alxn:RoyaltyBasedFinancingAgreement


Long
Period End2021-03-312020-12-312020-09-30
Value188187185
Percentage of LongTermDebt0.00.00.0
Percentage of Assets1.01.01.1
Percentage of Assets alxn:HealthCareRoyaltyPartners alxn:RoyaltyBasedFinancingAgreement0.00.00.0

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

alxn:SeniorSecuredTermLoan, alxn:CreditAgreement, us-gaap:LineOfCredit


Long
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312018-12-312018-09-302018-06-30
Value23512383241624492514261226122612
Percentage of LongTermDebt0.00.00.00.00.00.00.00.0
Percentage of Assets12.613.213.814.714.318.818.919.4
Percentage of Assets alxn:SeniorSecuredTermLoan alxn:CreditAgreement us-gaap:LineOfCredit0.00.00.00.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent

us-gaap:LongTermDebtNoncurrent


Long
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value2388241924532311237524062438247025012533256427202763284628882929317132123281332533680.09.5456577891011011131802470.0
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets12.813.414.013.813.516.216.717.618.018.319.020.020.321.221.822.024.325.125.025.325.60.00.21.32.02.53.23.83.94.57.312.20.0

us-gaap:LongTermDebtNoncurrent us-gaap:CounterpartyName, us-gaap:DebtInstrument

alxn:HealthCareRoyaltyPartners, alxn:RoyaltyBasedFinancingAgreement


Long
Period End2021-03-312020-12-312020-09-30
Value172171173
Percentage of LongTermDebtNoncurrent7.27.17.1
Percentage of Assets0.90.91.0
Percentage of Assets alxn:HealthCareRoyaltyPartners alxn:RoyaltyBasedFinancingAgreement0.00.00.0

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312018-12-312017-12-312016-12-312015-12-31
Value16391632181819462081391365396529
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.89.010.411.711.92.82.73.04.0

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-03-31
Value14
Percentage of MinorityInterest100.0
Percentage of Assets0.1

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value290298297289265280269267155129132140118110901311241077382217755345475242362218129.96911109.6449.3242.158
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.71.71.71.51.91.81.91.10.91.01.00.90.80.71.01.00.80.60.61.71.71.31.41.41.71.51.40.90.70.50.50.80.90.80.90.3

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent


Operating
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value1701771751691641661651500.0
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.0100.0100.0100.00.0
Percentage of Assets0.91.01.01.00.91.11.11.10.0

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-31
Value32
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0
Percentage of Assets0.2

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-31
Value25
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0
Percentage of Assets0.1

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-31
Value22
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0
Percentage of Assets0.1

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value20
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0
Percentage of Assets0.1

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value103
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0
Percentage of Assets0.6

Operating Lease Liability

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiability


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value205182184185168
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0
Percentage of Assets1.11.01.21.31.2

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value237223225231215
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0100.0100.0100.0100.0
Percentage of Assets1.31.31.51.61.5

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-312019-12-31
Value3240
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0100.0
Percentage of Assets0.20.2

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value1241611651110741049011747112711036710163970691659169876791128893894488568694850481998062825882528552351633022700238223542211209019701872174912131134953901859688247101
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets66.664.463.162.80.064.270.069.869.365.866.265.00.065.565.665.965.664.062.963.062.962.765.079.778.679.971.877.278.677.875.474.771.260.181.380.878.185.087.50.00.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312010-12-312009-12-312008-12-312007-12-31
Value-124.6-119.2-110.9-101.5-66.8-48.2-57.9-20.5-9.76.9-2.9-45.7-34.4606256-24.0-7.14-1.9422.947-1.443
Percentage of StockholdersEquity-1.1-1.1-1.1-0.9-0.6-0.5-0.6-0.2-0.10.1-0.0-0.5-0.40.70.81.7-1.0-0.8-0.31.2-1.4
Percentage of Assets-0.7-0.7-0.70.0-0.4-0.3-0.4-0.1-0.10.0-0.00.0-0.30.50.51.3-0.7-0.7-0.20.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value915290308942886488048738867786048539848184208350829079577726259221061852126111731093941833
Percentage of StockholdersEquity78.681.585.275.578.184.385.488.693.292.596.091.693.291.593.678.588.494.0111.2136.5158.9381.1820.9
Percentage of Assets50.651.553.50.050.259.059.661.561.361.362.40.061.060.058.861.763.570.990.5116.0139.10.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value5243470741295197463937503283282323252370204024972242181811801036379126-128.619-303.934-400.964-696.13-729.279
Percentage of StockholdersEquity45.042.539.444.241.236.232.329.125.425.923.327.425.220.914.331.415.96.4-11.3-35.4-58.2-281.8-718.2
Percentage of Assets29.026.824.70.026.425.322.520.216.717.115.10.016.513.79.024.711.44.8-9.2-30.0-51.00.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-2620.3-2543.7-2470.0-2213.0-2105.9-2073.4-1738.8-1701.2-1689.9-1689.9-1689.9-1689.9-1604.9-1141.0-710.663-382.964-80.365-14.229-2.676-2.676-2.676-1.26-1.26
Percentage of StockholdersEquity-22.5-23.0-23.5-18.8-18.7-20.0-17.1-17.5-18.4-18.4-19.3-18.5-18.0-13.1-8.6-11.6-3.4-0.7-0.2-0.3-0.4-0.5-1.2
Percentage of Assets-14.5-14.5-14.80.0-12.0-14.0-11.9-12.2-12.1-12.2-12.50.0-11.8-8.6-5.4-9.1-2.4-0.5-0.2-0.3-0.30.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-31
Value12431116511174711271
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0
Percentage of Assets66.764.40.064.2

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-31
Value-85.2-124.6-101.5-66.8
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-0.7-1.1-0.9-0.6
Percentage of Assets-0.5-0.70.0-0.4
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-31
Value9243915288648804
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest74.478.675.578.1
Percentage of Assets49.650.60.050.2
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.0

us-gaap:NoncontrollingInterest


Stockholders
Period End2021-03-31
Value14
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.1
Percentage of Assets0.1
Percentage of Assets us-gaap:NoncontrollingInterest0.0

us-gaap:Parent


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-31
Value12416116511174711271
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest99.9100.0100.0100.0
Percentage of Assets66.664.40.064.2
Percentage of Assets us-gaap:Parent0.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-31
Value5879524351974639
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest47.345.044.241.2
Percentage of Assets31.529.00.026.4
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2021-03-312020-12-312020-03-312019-12-31
Value-2620.5-2620.3-2213.0-2105.9
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-21.1-22.5-18.8-18.7
Percentage of Assets-14.1-14.50.0-12.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.0

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value9243915290308942880487388677860485398481842082908209806079577906785277937726764276592713259222912106204919681899185218271782129112611218119511731093
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets49.650.651.553.550.259.059.661.561.361.362.461.060.260.060.059.560.360.958.858.158.261.561.767.863.567.269.970.770.972.972.564.090.5103.3103.5116.0139.1

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value5879524347074129463937503283282323252370204022422212196918181724138712721180111312971127103653837939830420812645-46.948-83.206-128.619-242.359-277.104-303.934-400.964
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.529.026.824.726.425.322.520.216.717.115.116.516.214.713.713.010.69.99.08.59.925.524.715.911.413.110.87.84.81.8-1.9-4.1-9.2-20.5-24.0-30.0-51.0

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value-85.2-124.6-119.2-110.9-101.5-66.8-48.2-57.9-20.5-9.76.9-2.9-45.7-34.4-37.0-13.83660-16.6170.6943.8156254621195648-32.45-26.435-22.857-12.22319306.6352.345167.5564.179-19.627-14.275-7.14-1.942
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.5-0.7-0.7-0.70.0-0.4-0.3-0.4-0.1-0.10.0-0.00.0-0.3-0.30.00.30.5-0.10.00.00.50.40.52.71.40.00.0-0.8-0.7-0.40.71.20.30.10.70.40.3-1.7-1.2-0.7-0.2

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Accumulated
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-312009-12-31
Value-10.2-10.2-9.2-9.2-9.2-9.2-2.6-2.6-2.6-2.6-4.1-4.1-4.1-4.8-7.0-6.4-7.0-7.0-8.364-8.379-7.468-9.589-15.083-24.015-16.822-16.57-14.757-14.187-11.502-11.502-8.394-8.396-5.713-5.712-4.984-4.984-4.183-4.183-3.018-1.12
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax12.08.27.78.39.113.85.44.512.726.8-59.4141.49.014.018.946.4-19.4-11.750.3-1207.3-195.8-15.4-27.7-38.4-14.1-29.2-30.443.743.550.368.7-43.0-18.5-86.1-212.5-30.1-55.4-100.142.357.7
Percentage of Assets-0.1-0.1-0.1-0.10.0-0.1-0.0-0.0-0.0-0.0-0.0-0.00.0-0.0-0.10.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.2-0.4-0.40.00.0-0.3-0.3-0.3-0.3-0.2-0.2-0.2-0.2-0.2-0.3-0.3-0.1
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Accumulated
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-50.2-102.7-87.3-77.8-66.6-40.1-26.1-38.30.69.63321-29.3-13.9
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax58.982.473.270.265.660.054.166.1-2.9-99.0478.3-744.864.140.4
Percentage of Assets-0.3-0.6-0.5-0.50.0-0.2-0.2-0.30.00.10.20.20.0-0.1
Percentage of Assets us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedGainLossNetCashFlowHedgeParent


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value-102.7-40.19.6-13.99192
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax82.460.0-99.040.4153.2148.8
Percentage of Assets-0.6-0.20.1-0.10.70.7
Percentage of Assets us-gaap:AccumulatedGainLossNetCashFlowHedgeParent0.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Accumulated
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-312009-12-31
Value-24.8-11.7-22.7-23.9-25.4-17.4-19.4-16.9-18.4-16.4-21.9-20.2-12.1-15.9-15.0-17.5-21.0-24.0-17.386-17.874-17.999-19.995-19.784-17.937-19.107-13.719-9.826-6.83-6.876-7.382-3.352-4.338-4.258-2.809-2.718-3.702-2.576-2.959-1.631-1.103
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax29.19.419.021.625.026.040.229.289.8169.1-317.4696.626.546.240.5126.8-58.3-40.0104.6-2575.5-471.8-32.1-36.3-28.7-16.0-24.2-20.321.026.032.327.4-22.2-13.8-42.3-115.9-22.4-34.1-70.822.856.8
Percentage of Assets-0.1-0.1-0.1-0.10.0-0.1-0.1-0.1-0.1-0.1-0.2-0.10.0-0.1-0.10.0-0.2-0.2-0.1-0.1-0.1-0.2-0.2-0.1-0.4-0.30.00.0-0.2-0.2-0.1-0.2-0.2-0.1-0.1-0.2-0.1-0.2-0.2-0.1
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Treasury Stock Value

us-gaap:TreasuryStockValue

us-gaap:TreasuryStockValue


Treasury
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-06-302011-03-312010-12-312009-12-31
Value26202620254324702105207317381701168916891689160414401209114111101041100771055846644238210280808049142.6762.6762.6762.6762.6762.6762.6762.676
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets14.114.514.514.812.014.011.912.212.112.212.511.810.69.08.68.48.07.95.44.23.510.09.13.02.42.62.91.80.50.10.10.10.20.20.20.30.3

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-03-31
Value14
Percentage of MinorityInterest100.0
Percentage of Assets0.1

Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue


Adjustments
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value76857064576059605551445351
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Adjustments
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value76857067576059605551445351
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue100.3100.1100.3105.1100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Parent


Adjustments
Period End2021-03-312020-03-31
Value7657
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue100.0100.0
Percentage of Assets0.00.0
Percentage of Assets us-gaap:Parent0.00.0

us-gaap:TreasuryStock


Adjustments
Period End2021-03-312020-12-312020-09-302020-06-30
Value-0.2-0.1-0.2-3.3
Percentage of AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue-0.3-0.1-0.3-5.1
Percentage of Assets0.00.00.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value63784082279054951759953842983387-343.829925727028030838229124316719022323823283281106-31.055208144974610414110162907678244521
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.052.851.854.738.037.447.544.737.77.437.7-32.932.228.331.430.735.446.136.532.424.027.233.537.53.847.350.720.7-5.547.336.026.413.732.748.037.025.739.937.442.414.736.118.3

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-133.9-80.6-1267.414-766.056-8.5-41.02.952104568-254.70.7-170.5-253.5-495.0114-65.218-330.675-5.665-161.59-195.194-3179.966-48.423-57.179-75.5740.081-90.197-613.271-216.331-191.97-5.569-7.59-6.239-4.559-609.1970.6617.59230-72.965-21.644-2.276
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.2-5.1-79.81.0-53.04.1-0.7-3.40.34.610.254.4-27.40.1-19.8-27.8-56.913.8-8.2-43.9-0.8-23.1-29.3-500.0-8.1-9.5-13.60.0-15.9-138.8-54.0-51.9-1.6-2.4-2.1-1.7-248.90.33.716.7-43.9-17.2-1.9

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-18.7-73.8-107.4-292.5-138.2-59.7-365.9-61.1-252.43.1117.0-123.5-225.6-95.3-206.7-69.0-283.463-62.187-24.093-466.257-181.31-185.02833465.074-30.112-59.394-22.5811924446.967-4.308-12.506-36.688350364128.409-52.104693.47410
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.1-4.6-6.8-20.2-9.6-4.3-29.0-5.1-22.10.31.10.7-13.3-24.8-11.1-22.6-7.9-34.1-7.8-3.2-66.6-25.9-27.8526.20.8-5.0-10.7-4.421.05.511.11.9-1.3-3.9-12.5127.7149.05.64.1-28.142.12.89.1

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


Cash
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value471706-544.4517-367.8520218438179138498219-72.6348.3
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax28.844.4-34.335.8-25.537.617.336.415.712.248.521.0-7.83.81.0

Amortization Of Financing Costs

us-gaap:AmortizationOfFinancingCosts

us-gaap:AmortizationOfFinancingCosts


Amortization
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value1200000.04700000.01200000.01200000.01200000.01300000.01300000.01200000.01300000.01300000.03200000.02300000.02200000.02000000.02300000.02000000.02722000.02382000.02382000.03000000.02136000.02513000.0
Percentage of AmortizationOfFinancingCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Depreciation Depletion And Amortization

us-gaap:DepreciationDepletionAndAmortization

us-gaap:DepreciationDepletionAndAmortization


Depreciation
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value7575758989909296979810410010118510910299100100979693491210189.3539.7749.2688.4547.2256.7486.2666.2746.1945.5445.8754.4144.4964.3894.3173.9913.842
Percentage of DepreciationDepletionAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Accounts Receivable

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInAccountsReceivable


Increase
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value87-44.145161201202.7101951160944220-11.4433.0-7.87564273724-18.03250585.406139.242-0.063184328267.57123212026169.208266.70717
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Inventories

us-gaap:IncreaseDecreaseInInventories

us-gaap:IncreaseDecreaseInInventories


Increase
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value59-105.3-4.852-37.35181121141-30.88.0-3.9193514191133353.8388112-2.096-2.62640-8.7551420-5.118-9.3998.9225.4692.798-5.823-0.4569.7461.3161.363-0.879101.02112
Percentage of IncreaseDecreaseInInventories100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value63784082279054951759953842983387-343.829925727028030838229124316719022323823283281106-31.055208144974610414110162907678244521
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.052.851.854.738.037.447.544.737.77.437.7-32.932.228.331.430.735.446.136.532.424.027.233.537.53.847.350.720.7-5.547.336.026.413.732.748.037.025.739.937.442.414.736.118.3

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value636535578-1068.1557889467459587-45.0330-457.4249307816517093941149266-183.75717091153177166159-18.992939582809236454865342626272120
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 RevenueFromContractWithCustomerExcludingAssessedTax38.933.736.4-73.938.664.237.038.251.6-4.032.2-43.826.83.39.118.119.511.211.815.313.29.5-27.626.815.225.632.032.528.1-4.323.425.924.325.331.313.218.621.232.118.716.217.019.717.317.8

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

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Net
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-17.9-12.8-0.35.211109.05.61.2-9.0
Percentage of NetIncomeLoss-2.8-2.20.00.92.42.31.51.7-0.3-3.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.1-0.8-0.00.40.90.90.80.50.1-1.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest151.7256.0-3.245.6101.8114.3128.6169.7-70.668.7

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value535578-1068.1889467459587-45.0330-457.4249
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.736.4-73.964.237.038.251.6-4.032.2-43.826.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-03-312020-03-31
Value489557
Percentage of ProfitLoss100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax29.938.6

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-03-31
Value-146.8
Percentage of ProfitLoss-30.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-9.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.0

us-gaap:Parent


Profit
Period End2021-03-312020-03-31
Value636557
Percentage of ProfitLoss130.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.938.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:Parent0.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-03-312020-03-31
Value636557
Percentage of ProfitLoss130.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.938.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.0

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value76857067576059605652455351715760544046475666516742332828231921171613141213101111118.258.104
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-133.9-80.6-1267.414-766.056-8.5-41.02.952104568-254.70.7-170.5-253.5-495.0114-65.218-330.675-5.665-161.59-195.194-3179.966-48.423-57.179-75.5740.081-90.197-613.271-216.331-191.97-5.569-7.59-6.239-4.559-609.1970.6617.59230-72.965-21.644-2.276
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.2-5.1-79.81.0-53.04.1-0.7-3.40.34.610.254.4-27.40.1-19.8-27.8-56.913.8-8.2-43.9-0.8-23.1-29.3-500.0-8.1-9.5-13.60.0-15.9-138.8-54.0-51.9-1.6-2.4-2.1-1.7-248.90.33.716.7-43.9-17.2-1.9

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value2077106.212304146364241626688931007510794666480767357522243178.7016.6168.5195.4937.5896.2394.2523.7666.7415.4057.6142.2223.1862.317
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-18.7-73.8-107.4-292.5-138.2-59.7-365.9-61.1-252.43.1117.0-123.5-225.6-95.3-206.7-69.0-283.463-62.187-24.093-466.257-181.31-185.02833465.074-30.112-59.394-22.5811924446.967-4.308-12.506-36.688350364128.409-52.104693.47410
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.1-4.6-6.8-20.2-9.6-4.3-29.0-5.1-22.10.31.10.7-13.3-24.8-11.1-22.6-7.9-34.1-7.8-3.2-66.6-25.9-27.8526.20.8-5.0-10.7-4.421.05.511.11.9-1.3-3.9-12.5127.7149.05.64.1-28.142.12.89.1

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt


Repayments
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312011-09-30
Value32323232323232320.00.00.025043444343442000.00.0175430.04512121212191212120.012670.00.0
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.00.0

Payments For Repurchase Of Common Stock

us-gaap:PaymentsForRepurchaseOfCommonStock

us-gaap:PaymentsForRepurchaseOfCommonStock


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value76732531073233437110.00.00.085164601706830693429615291236019104156220.00.03135110.00.00.0
Percentage of PaymentsForRepurchaseOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.00.00.00.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-30
Value18.8-419.013.30.2116.0-0.1420.1270.079-0.0850.1260.033-0.0930.2920.093-0.3450.1990.124-0.0430.4030.3240.358-0.1062.3190.040.1460.0020.2480.2390.2480.2190.3020.3010.296-0.0420.3450.5560.330.0540.0020.2920.3430.321
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value2.23.03.65.36.06.2216.428.6199.5571112
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice


Share
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value134.15119.51119.68124.71116.65110.1585.6550.6935.9221.8315.27
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value267025176416968095662538561178212
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value16313392601391132846129.7738.6587.3059.569
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:DeferredTaxAssetsValuationAllowance


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value27672193.44.04.9461.1171.9342.9413.0742.47
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:AmortizationofIntangibleAssetsAcquired

alxn:AmortizationofIntangibleAssetsAcquired


Amortizationof
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-03-312013-03-31
Value53535373737375808080808080808080807982808079360.00.00.00.00.00.104
Percentage of AmortizationofIntangibleAssetsAcquired100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.0100.0

alxn:AssetAcquisitionConsiderationTransferred us-gaap:SubsequentEventType

alxn:AssetAcquisitionConsiderationTransferred

us-gaap:SubsequentEvent


Asset
Period End2021-01-31
Value100
Percentage of AssetAcquisitionConsiderationTransferred100.0

alxn:AssetAcquisitionContingentConsiderationMilestonePayments

alxn:AssetAcquisitionContingentConsiderationMilestonePayments


Asset
Period End2020-12-312020-06-302019-09-30
Value0.0160100
Percentage of AssetAcquisitionContingentConsiderationMilestonePayments0.0100.0100.0

alxn:BusinessCombinationConsiderationTransferredNet us-gaap:BusinessAcquisition

alxn:BusinessCombinationConsiderationTransferredNet

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value1424
Percentage of BusinessCombinationConsiderationTransferredNet100.0

alxn:BusinessCombinationConsiderationTransferredPerShare us-gaap:BusinessAcquisition

alxn:BusinessCombinationConsiderationTransferredPerShare

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value18.0
Percentage of BusinessCombinationConsiderationTransferredPerShare100.0

alxn:BusinessCombinationConsiderationTransferredPerShare us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType

alxn:PortolaPharmaceuticalsInc, us-gaap:SubsequentEvent


Business
Period End2020-07-02
Value18.0
Percentage of BusinessCombinationConsiderationTransferredPerShare100.0

alxn:BusinessCombinationContingentConsiderationArrangementsExpectedPaymentsNextTwelveMonths

alxn:BusinessCombinationContingentConsiderationArrangementsExpectedPaymentsNextTwelveMonths


Business
Period End2021-03-31
Value120
Percentage of BusinessCombinationContingentConsiderationArrangementsExpectedPaymentsNextTwelveMonths100.0

alxn:BusinessCombinationMergerPayment us-gaap:BusinessAcquisition

alxn:BusinessCombinationMergerPayment

alxn:AstraZeneca


Business
Period End2020-12-12
Value1180
Percentage of BusinessCombinationMergerPayment100.0

alxn:BusinessCombinationOwnershipPercentageOfCombinedCompany us-gaap:StatementScenario, us-gaap:BusinessAcquisition

alxn:BusinessCombinationOwnershipPercentageOfCombinedCompany

srt:ScenarioForecast, alxn:AstraZeneca


Business
Period End2021-09-30
Value15.0
Percentage of BusinessCombinationOwnershipPercentageOfCombinedCompany100.0

alxn:BusinessCombinationPaymentIfMergerIsTerminated dei:LegalEntity, us-gaap:BusinessAcquisition

alxn:BusinessCombinationPaymentIfMergerIsTerminated

alxn:AstraZeneca, alxn:AstraZeneca


Business
Period End2020-12-12
Value1415
Percentage of BusinessCombinationPaymentIfMergerIsTerminated100.0

alxn:BusinessCombinationPaymentIfMergerIsTerminated us-gaap:BusinessAcquisition

alxn:AstraZeneca


Business
Period End2020-12-12
Value270
Percentage of BusinessCombinationPaymentIfMergerIsTerminated19.1

alxn:BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCostOfGoodsSold us-gaap:BusinessAcquisition

alxn:BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCostOfGoodsSold

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-12-312019-12-312019-09-30
Value0.17.710
Percentage of BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCostOfGoodsSold100.0100.0100.0

alxn:BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibleAssetAmortizationExpense us-gaap:BusinessAcquisition

alxn:BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibleAssetAmortizationExpense

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-12-312019-12-312019-09-30
Value0.11919
Percentage of BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibleAssetAmortizationExpense100.0100.0100.0

alxn:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostNotExpensed

alxn:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostNotExpensed


Business
Period End2020-12-312020-09-302020-03-31
Value7.37253
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostNotExpensed100.0100.0100.0

alxn:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresTransactionCosts

alxn:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresTransactionCosts


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-06-30
Value5400000.09900000.01800000.04200000.01400000.00
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresTransactionCosts100.0100.0100.0100.0100.00.0

alxn:BusinessCombinationTotalConsideration us-gaap:BusinessAcquisition

alxn:BusinessCombinationTotalConsideration

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value1621
Percentage of BusinessCombinationTotalConsideration100.0

alxn:CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonths

alxn:CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonths


Collaboration
Period End2021-03-31
Value155
Percentage of CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonths100.0

alxn:CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonthsConsolidatedPotentialMilestonePayments us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonthsConsolidatedPotentialMilestonePayments

alxn:CaelumBiosciences, us-gaap:CollaborativeArrangement


Collaboration
Period End2021-03-31
Value14
Percentage of CollaborationAgreementMilestonePaymentsToBeMadeNextTwelveMonthsConsolidatedPotentialMilestonePayments100.0

alxn:CollaborationAgreementPotentialFuturePaymentsAdditionalMilestoneAchievement us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:CollaborationAgreementPotentialFuturePaymentsAdditionalMilestoneAchievement

alxn:Zealand, alxn:ZealandPharma


Collaboration
Period End2021-03-312020-12-31
Value1150.0
Percentage of CollaborationAgreementPotentialFuturePaymentsAdditionalMilestoneAchievement100.00.0

alxn:CollaborationAgreementPotentialFuturePaymentsMaximumRegulatoryAndCommercialMilestonePayments us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:CollaborationAgreementPotentialFuturePaymentsMaximumRegulatoryAndCommercialMilestonePayments

alxn:CaelumBiosciences, us-gaap:CollaborativeArrangement


Collaboration
Period End2021-03-31
Value350
Percentage of CollaborationAgreementPotentialFuturePaymentsMaximumRegulatoryAndCommercialMilestonePayments100.0

alxn:CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement

alxn:CaelumBiosciences, us-gaap:CollaborativeArrangement


Collaboration
Period End2020-09-302020-06-302019-01-31
Value151530
Percentage of CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement100.0100.0100.0

alxn:EidosMember, alxn:AffibodyABDomain


Collaboration
Period End2021-03-312020-09-30
Value300.0
Percentage of CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement0.00.0

alxn:Zealand, alxn:ZealandPharma


Collaboration
Period End2021-03-312020-12-312020-09-302019-09-302019-06-302019-03-31
Value6100.00.00.00.0610
Percentage of CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement0.00.00.00.00.00.0

alxn:CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement us-gaap:TypeOfArrangement

alxn:CollaborationandLicenseAgreement


Collaboration
Period End2021-03-312020-12-312020-09-302019-12-312019-09-302019-06-302019-03-31
Value1140.071-780.6-3.60.0838
Percentage of CollaborationAgreementPotentialFuturePaymentsMilestoneAchievement0.00.0476.70.00.00.00.0

alxn:CollaborationAgreementPotentialFuturePaymentsOptionFee us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:CollaborationAgreementPotentialFuturePaymentsOptionFee

alxn:Zealand, alxn:ZealandPharma


Collaboration
Period End2021-03-312020-12-31
Value150.0
Percentage of CollaborationAgreementPotentialFuturePaymentsOptionFee100.00.0

alxn:CollaborationAgreementPotentialFuturePaymentsUpfrontOptionExercisePayment us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:CollaborationAgreementPotentialFuturePaymentsUpfrontOptionExercisePayment

alxn:CaelumBiosciences, us-gaap:CollaborativeArrangement


Collaboration
Period End2021-03-31
Value150
Percentage of CollaborationAgreementPotentialFuturePaymentsUpfrontOptionExercisePayment100.0

alxn:ConsolidationOfNoncontrollingInterestIncludingNoncashExpenseForAcquiredAssets

alxn:ConsolidationOfNoncontrollingInterestIncludingNoncashExpenseForAcquiredAssets


Consolidation
Period End2021-03-31
Value210
Percentage of ConsolidationOfNoncontrollingInterestIncludingNoncashExpenseForAcquiredAssets100.0

alxn:EffectiveIncomeTaxRateReconciliationIntangibleAssetImpairmentPercent

alxn:EffectiveIncomeTaxRateReconciliationIntangibleAssetImpairmentPercent


Effective
Period End2020-12-31
Value-380.4
Percentage of EffectiveIncomeTaxRateReconciliationIntangibleAssetImpairmentPercent100.0

alxn:FairValueInputDiscountRate us-gaap:BusinessAcquisition, us-gaap:PropertyPlantAndEquipmentByType

alxn:FairValueInputDiscountRate

alxn:PortolaPharmaceuticalsInc, alxn:AndexxaProductLine


Fair
Period End2020-07-02
Value17.5
Percentage of FairValueInputDiscountRate100.0

alxn:FairValueInputDiscountRate us-gaap:Range, us-gaap:BusinessAcquisition

srt:Maximum, alxn:PortolaPharmaceuticalsInc


Fair
Period End2020-07-02
Value7.1
Percentage of FairValueInputDiscountRate40.6

srt:Minimum, alxn:PortolaPharmaceuticalsInc


Fair
Period End2020-07-02
Value3.3
Percentage of FairValueInputDiscountRate18.9

alxn:FairValueInputsCostOfDebt us-gaap:Range, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

alxn:FairValueInputsCostOfDebt

srt:Maximum, us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Fair
Period End2021-03-312020-12-312020-09-302020-01-28
Value3.0-1.04.2930.023
Percentage of FairValueInputsCostOfDebt100.0100.0100.0100.0

srt:Minimum, us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Fair
Period End2021-03-312020-12-312020-09-302020-01-28
Value2.5-1.13.8960.021
Percentage of FairValueInputsCostOfDebt83.3110.090.891.3

alxn:FairValueInputsWeightedAverageCostOfCapital

alxn:FairValueInputsWeightedAverageCostOfCapital


Fair
Period End2021-03-312020-12-312020-09-30
Value11.5011.385
Percentage of FairValueInputsWeightedAverageCostOfCapital100.00.0100.0

alxn:FairValueOfEquitySharesOfBusinessCombination

alxn:FairValueOfEquitySharesOfBusinessCombination


Fair
Period End2020-12-31
Value0.0
Percentage of FairValueOfEquitySharesOfBusinessCombination0.0

alxn:NoncashOrPartNoncashAcquisitionContingentConsiderationIssued

alxn:NoncashOrPartNoncashAcquisitionContingentConsiderationIssued


Noncash
Period End2020-12-312020-09-302020-06-302020-03-31
Value0.00.00.0155
Percentage of NoncashOrPartNoncashAcquisitionContingentConsiderationIssued0.00.00.0100.0

alxn:OperatingRightOfUseAssetsExchangedForOperatingLeaseLiability

alxn:OperatingRightOfUseAssetsExchangedForOperatingLeaseLiability


Operating
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302018-09-30
Value1.55.3123.73.20.0
Percentage of OperatingRightOfUseAssetsExchangedForOperatingLeaseLiability100.0100.0100.0100.0100.00.0

alxn:ProceedsFromSaleAndMaturityOfDebtSecuritiesAvailableForSaleAndCashEquivalents

alxn:ProceedsFromSaleAndMaturityOfDebtSecuritiesAvailableForSaleAndCashEquivalents


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value0.099999999999880825204812561645798
Percentage of ProceedsFromSaleAndMaturityOfDebtSecuritiesAvailableForSaleAndCashEquivalents100.0100.0100.0100.0100.0100.0100.0

alxn:RestructuringChargesAndAccrualAdjustment

alxn:RestructuringChargesAndAccrualAdjustment


Restructuring
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value-0.7-3.2140.0-0.80.10.32.59.1-0.910105.55.6722.9241.2590.5640.4550.722117.461167.052150.00.00.0
Percentage of RestructuringChargesAndAccrualAdjustment100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

alxn:RestructuringChargesEstimatedAdditionalCharge

alxn:RestructuringChargesEstimatedAdditionalCharge


Restructuring
Period End2020-09-30
Value11
Percentage of RestructuringChargesEstimatedAdditionalCharge100.0

alxn:RoyaltyAgreementInterestToBeAccrued

alxn:RoyaltyAgreementInterestToBeAccrued


Royalty
Period End2021-03-312020-09-30
Value7990
Percentage of RoyaltyAgreementInterestToBeAccrued100.0100.0

alxn:TaxAdjustmentsSettlementsAndUnusualProvisionsNet

alxn:TaxAdjustmentsSettlementsAndUnusualProvisionsNet


Tax
Period End2020-12-31
Value17
Percentage of TaxAdjustmentsSettlementsAndUnusualProvisionsNet100.0

us-gaap:BusinessAcquisitionsProFormaNetIncomeLoss

us-gaap:BusinessAcquisitionsProFormaNetIncomeLoss


Business
Period End2021-03-312020-12-312020-09-302020-03-312019-12-312019-09-302015-12-312015-09-302015-06-302014-12-312014-09-302014-06-30
Value57454362551574937268-177.8549879111116
Percentage of BusinessAcquisitionsProFormaNetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessAcquisitionsProFormaRevenue

us-gaap:BusinessAcquisitionsProFormaRevenue


Business
Period End2021-03-312020-12-312020-09-302020-03-312019-12-312019-09-302015-12-312015-09-302015-06-302014-12-312014-09-302014-06-30
Value144415911589114014131299700666637600556514
Percentage of BusinessAcquisitionsProFormaRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationAcquisitionRelatedCosts

us-gaap:BusinessCombinationAcquisitionRelatedCosts


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1311634.6380.0-0.3750.00.00.3750.1560.02611200.00.0-0.038-1.9452.5731.1673.2343.3650.9674.807132.3220.2361.09.928
Percentage of BusinessCombinationAcquisitionRelatedCosts100.0100.0100.0100.0100.00.0100.00.00.0100.0100.00.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationConsiderationTransferred1 us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationConsiderationTransferred1

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value1369
Percentage of BusinessCombinationConsiderationTransferred1100.0

us-gaap:BusinessCombinationConsiderationTransferred1 us-gaap:BusinessAcquisition, us-gaap:SubsequentEventType

alxn:PortolaPharmaceuticalsInc, us-gaap:SubsequentEvent


Business
Period End2020-07-02
Value1380
Percentage of BusinessCombinationConsiderationTransferred1100.8

us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value41
Percentage of BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable100.0

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value9.21623155.84.4296.1-28.75.6534.7529.04.0244.05.324405.186-14.818294.04411108.3031.989-0.0382.211
Percentage of BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1 us-gaap:BusinessAcquisition

alxn:Achillion


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-03-31
Value2.21.319271.7
Percentage of BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability123.98.082.5174.729.3

us-gaap:BusinessCombinationIntegrationRelatedCosts

us-gaap:BusinessCombinationIntegrationRelatedCosts


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-06-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-30
Value4.1134.60.90.10.00.0620.00.9740.9643.2026.0752.9780.00.00.00.0
Percentage of BusinessCombinationIntegrationRelatedCosts100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.00.00.00.00.0

us-gaap:BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual

alxn:Achillion


Business
Period End2020-12-312020-09-302020-06-302020-03-31
Value-118.22412-13.9
Percentage of BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual100.0100.0100.0100.0

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-12-312020-09-30
Value-45.1-35.4
Percentage of BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual38.2-143.9

us-gaap:BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-12-312020-09-30
Value3938
Percentage of BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual100.0100.0

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-06-30
Value13117634.6380.0
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed100.0100.0100.0100.0100.00.0

us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed us-gaap:BusinessAcquisition

alxn:Achillion


Business
Period End2021-03-312020-12-312020-09-302020-06-30
Value380.10.0-0.1
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed288.60.10.0-2.2

alxn:AstraZeneca


Business
Period End2021-03-31
Value8.2
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed62.1

alxn:PortolaPharmaceuticalsInc


Business
Period End2021-03-312020-12-312020-09-302020-06-30
Value5.09.8634.7
Percentage of BusinessCombinationSeparatelyRecognizedTransactionsAdditionalDisclosuresAcquisitionCostExpensed37.98.3100.0102.2

us-gaap:BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1 us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value7200000.0
Percentage of BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1100.0

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CapitalExpendituresIncurredButNotYetPaid


Capital
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value5.40.62.3-1.01310-11.23.51011-5.6-16.3321.7-2.45.4300.314-3.5521.398244.9023.8669.863112.799140.00.0
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:ContributionOfProperty

us-gaap:ContributionOfProperty


Contribution
Period End2021-03-312020-12-31
Value5.00.0
Percentage of ContributionOfProperty100.00.0

us-gaap:DebtInstrumentPeriodicPayment us-gaap:CreditFacility, us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentPeriodicPayment

alxn:SeniorSecuredTermLoan, alxn:CreditAgreement, us-gaap:LineOfCredit


Debt
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-30
Value323232323232
Percentage of DebtInstrumentPeriodicPayment100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxesAndTaxCredits

us-gaap:DeferredIncomeTaxesAndTaxCredits


Deferred
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value52-109.252-275.649-319.3-95.340-81.1-46.2-32.4228811-78.522-1.08.2291946299.5838921-24.8236.551-48.031-54.114-58.31175-8.9490.165251354-19.9222326-4.0079.112106.5676.333
Percentage of DeferredIncomeTaxesAndTaxCredits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred

us-gaap:InterestRateContract, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312017-03-31
Value-45.745-45.5-5.5-8.8-15.910-3.3136.32.0
Percentage of DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation

us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument, us-gaap:Sales


Derivative
Period End2021-03-312020-09-302020-06-302019-09-302019-06-302019-03-312018-09-302016-09-30
Value9.7131124-12.7176.7-13.892
Percentage of DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred-21.229.8-24.8-276.179.9163.649.60.0

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Effect
Period End2021-03-312020-09-302020-06-302020-03-312019-09-30
Value-13100000.07600000.05100000.0-13200000.0-6800000.0
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense

us-gaap:EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense


Effective
Period End2021-03-31
Value5.2
Percentage of EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense100.0

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsForeign

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsForeign


Effective
Period End2020-12-31
Value3.1
Percentage of EffectiveIncomeTaxRateReconciliationTaxCreditsForeign100.0

us-gaap:EquityMethodInvestmentOtherThanTemporaryImpairment us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:EquityMethodInvestmentOtherThanTemporaryImpairment

alxn:CaelumBiosciencesOption


Equity
Period End2020-12-31
Value49
Percentage of EquityMethodInvestmentOtherThanTemporaryImpairment100.0

us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:EquityMethodInvestmentRealizedGainLossOnDisposal

alxn:PortolaPharmaceuticals


Equity
Period End2020-07-02
Value29
Percentage of EquityMethodInvestmentRealizedGainLossOnDisposal100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings

us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Fair
Period End2021-03-312020-12-31
Value-9200000.0-16200000.0
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings100.0100.0

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax

us-gaap:ForeignCurrencyTransactionGainLossBeforeTax


Foreign
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312018-09-302017-12-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-10.96.12.43.8-7.1-1.2-0.83.84.1-5.4-3.9-1.26-1.011-2.820.091-1.0592.795-2.0451.005-0.001-2.045-1.2021.258-0.841-0.547-0.090.503-0.391-0.416-0.186-0.215-1.329-0.841-0.5060.395-0.42-0.537
Percentage of ForeignCurrencyTransactionGainLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnDerivativeInstrumentsNetPretax

us-gaap:GainLossOnDerivativeInstrumentsNetPretax


Gain
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value19-10.3-7.6-3.5151.226-5.8-5.55.913-6.83.7-3.0-16.1
Percentage of GainLossOnDerivativeInstrumentsNetPretax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnDispositionOfAssets1

us-gaap:GainLossOnDispositionOfAssets1


Gain
Period End2021-03-312020-12-312020-09-30
Value250.014
Percentage of GainLossOnDispositionOfAssets1100.00.0100.0

us-gaap:GainLossOnDispositionOfAssets1 us-gaap:CounterpartyName

alxn:OriginBiosciences


Gain
Period End2021-03-312018-09-30
Value203.5
Percentage of GainLossOnDispositionOfAssets179.10.0

us-gaap:GainLossOnDispositionOfAssets1 us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

alxn:Inozyme


Gain
Period End2020-07-17
Value14
Percentage of GainLossOnDispositionOfAssets10.0

us-gaap:GainLossOnFairValueHedgesRecognizedInEarnings us-gaap:HedgingDesignation

us-gaap:GainLossOnFairValueHedgesRecognizedInEarnings

us-gaap:Nondesignated


Gain
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-312012-03-31
Value12-10.4-6.2-3.2160.81.4-5.83.25.96.818-8.1-3.0-0.5-9.0-2.528-5.146-12.9692.676-6.666.42312-1.642.2896.950.109
Percentage of GainLossOnFairValueHedgesRecognizedInEarnings100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnSaleOfPropertyPlantEquipment

us-gaap:GainLossOnSaleOfPropertyPlantEquipment


Gain
Period End2021-03-312012-06-302012-03-312011-06-302011-03-31
Value250.0-0.0170.00.0
Percentage of GainLossOnSaleOfPropertyPlantEquipment100.00.0100.00.00.0

us-gaap:GoodwillPurchaseAccountingAdjustments us-gaap:BusinessAcquisition

us-gaap:GoodwillPurchaseAccountingAdjustments

alxn:PortolaPharmaceuticalsInc


Goodwill
Period End2020-12-31
Value-600000.0
Percentage of GoodwillPurchaseAccountingAdjustments100.0

us-gaap:ImpairmentOfIntangibleAssetsExcludingGoodwill

us-gaap:ImpairmentOfIntangibleAssetsExcludingGoodwill


Impairment
Period End2020-12-312020-09-302020-06-302019-06-302018-12-312018-09-302018-06-302017-12-312017-09-302017-06-302016-12-312016-09-302015-03-312014-03-312013-03-31
Value0.02.384185791015625e-1320530.00.00.00.00.00.031850.00.03.4640.0
Percentage of ImpairmentOfIntangibleAssetsExcludingGoodwill0.0100.0100.00.00.00.00.00.00.0100.0100.00.00.0100.00.0

us-gaap:IncomeTaxReconciliationTaxCreditsForeign us-gaap:IncomeTaxAuthority

us-gaap:IncomeTaxReconciliationTaxCreditsForeign

us-gaap:DomesticCountry


Income
Period End2020-12-31
Value56
Percentage of IncomeTaxReconciliationTaxCreditsForeign100.0

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInAccountsPayableAndAccruedLiabilities


Increase
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-118.498112-20.3-68.22318331-8.2112-36.7-56.9-73.72963-0.439579935-42.4631-136.3472.898-13.6599888138-60.68238579.25-62.3211.778-16.94579-2.8452517315.44710-4.371
Percentage of IncreaseDecreaseInAccountsPayableAndAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets


Increase
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value-11.01937-18.172-11.2-84.6685870292332434.27613-22.897312265-22.847319.0893812-11.57451-33.63336133.362-13.522-0.02424-1.786-5.3720.011154.4381.0532.485-9.105
Percentage of IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements


Incremental
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-30
Value2500000.0400000.01500000.001000000.001200000.01400000.01700000.0100000.01700000.001600000.0-500000.02000000.01100000.02000000.0894000.01908000.01667000.01813000.067000.002312000.02673000.0-98000.03261000.03644000.04007000.045000.04049000.04052000.04286000.0-373000.07789000.08476000.08878000.0160000.08363000.08087000.08168000.06242000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IndefinitelivedIntangibleAssetsAcquired us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass

us-gaap:IndefinitelivedIntangibleAssetsAcquired

alxn:PriorityReviewVoucher


Indefinitelived
Period End2021-01-31
Value100
Percentage of IndefinitelivedIntangibleAssetsAcquired100.0

us-gaap:InventoryWriteDown

us-gaap:InventoryWriteDown


Inventory
Period End2020-12-312020-09-30
Value2.97.4
Percentage of InventoryWriteDown100.0100.0

us-gaap:InvestmentIncomeInvestmentExpense

us-gaap:InvestmentIncomeInvestmentExpense


Investment
Period End2021-03-312020-03-31
Value7000000.05200000.0
Percentage of InvestmentIncomeInvestmentExpense100.0100.0

us-gaap:InvestmentIncomeNet

us-gaap:InvestmentIncomeNet


Investment
Period End2020-09-302020-06-302019-09-302019-06-302018-09-302018-06-30
Value114123-14.95.97.7
Percentage of InvestmentIncomeNet100.0100.0100.0100.0100.0100.0

us-gaap:LitigationSettlementAmountAwardedToOtherParty us-gaap:LitigationCase

us-gaap:LitigationSettlementAmountAwardedToOtherParty

alxn:SEC


Litigation
Period End2020-07-02
Value21
Percentage of LitigationSettlementAmountAwardedToOtherParty100.0

us-gaap:LitigationSettlementAmountAwardedToOtherParty us-gaap:LitigationCase, us-gaap:SubsequentEventType

alxn:SEC, us-gaap:SubsequentEvent


Litigation
Period End2020-07-02
Value21
Percentage of LitigationSettlementAmountAwardedToOtherParty100.0

us-gaap:NoncontrollingInterestIncreaseFromBusinessCombination

us-gaap:NoncontrollingInterestIncreaseFromBusinessCombination


Noncontrolling
Period End2021-03-31
Value161
Percentage of NoncontrollingInterestIncreaseFromBusinessCombination100.0

us-gaap:NoncontrollingInterestIncreaseFromBusinessCombination us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Noncontrolling
Period End2021-03-31
Value161
Percentage of NoncontrollingInterestIncreaseFromBusinessCombination100.0

us-gaap:NoncontrollingInterestIncreaseFromBusinessCombination us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Noncontrolling
Period End2021-03-31
Value161
Percentage of NoncontrollingInterestIncreaseFromBusinessCombination100.0

us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value00300000.0-200000.0000200000.0-200000.0100000.00-400000.0-400000.00300000.01000000.0-1553000.0-1910000.01965000.01498000.0-940000.0135000.0-803000.01057000.0-422000.0-776000.0299000.0811000.0-129000.0210000.0-226000.00000
Percentage of OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent0.00.0100.0100.00.00.00.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value-13100000.011000000.01200000.01500000.0-8000000.02000000.0-2500000.01500000.0-2000000.05500000.0-1700000.0-8100000.03800000.0-600000.02000000.04100000.03000000.0-6609000.0488000.0125000.01996000.0-211000.0-1847000.01170000.0-5388000.0-3893000.0-2996000.046000.0506000.0-4030000.0986000.0-77000.0-1449000.0-91000.0984000.0-1126000.0
Percentage of OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value21-23.5-21.1-9.7-29.5-10.620-27.0-1.8-6.11545-20.9-0.5-23.5-40.5-15.089-8.9577.171-44.0782418-29.505882185-6.788-2.69829
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Other
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value34-22.3-11.5-21.323-28.50.01752-24.4
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax160.9105.7118.672.2112.0105.6-0.0111.1114.0116.7

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.00.00.3-0.20.00.00.00.2-0.10.10.5-0.4-0.20.00.00.0-1.893-1.52.061.333-0.9280.136-0.7891.065-0.407-0.7670.2990.812
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax-0.0-0.0-3.10.7-0.00.0-0.0-11.11.60.71.11.940.0-0.0-0.0-0.0-2.116.728.7-3.0-3.80.82.71.2-1.9-0.9-4.4-30.1

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-13.1111.21.5-8.02.0-2.51.5-2.05.5-1.7-8.13.8-0.62.26.80.0-6.6090.4880.1251.996-0.211-1.8471.17-5.388-3.893-2.9960.0460.506-1.449
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax-60.9-46.8-5.7-15.527.1-18.9-12.0-5.6111.1-90.2-11.1-17.7-18.2120.0-9.4-16.8-0.0-7.4-5.41.7-4.5-0.9-10.2-4.0-6.1-17.8-3.5-0.7-18.8-4.9

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax


Other
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value15-2.8-3.3-8.23.5-12.1-2.22.915-4.9
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax

us-gaap:ForeignExchangeForward, us-gaap:CashFlowHedging, us-gaap:Sales


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-9.1-8.6-4.07.48.87.48.67.05.47.52.5-1.3-10.1
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateContract, us-gaap:CashFlowHedging, us-gaap:InterestExpense


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-8.8-9.0-8.8-7.7-3.60.62.63.43.63.12.51.1
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax96.7104.7220.0-104.1-40.98.130.248.666.7124.0-192.3-10.9

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value39-5.4-8.3-9.4-34.7-18.69.7-37.4-10.8-16.69.842-11.32.1-23.0-49.8-24.076-17.311-3.121-58.4867.873-8.088-56.973628.28580-6.015-3.578-10.634-31.749-11.435-24.3274.29-14.1978.986-3.377
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent us-gaap:StatementEquityComponents

us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Other
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value52-9.5-11.2-26.512-38.9-9.01150-15.4
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent133.2114.5119.176.4125.8104.083.3116.3118.9136.3

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-30
Value0.00.00.3-0.20.00.00.00.2-0.20.10.0-0.4-0.40.1-0.11.0-1.553-1.911.9651.498-0.940.135-0.8031.057-0.422-0.7760.2990.811-0.1290.209
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent-0.0-0.0-3.20.6-0.00.0-0.0-1.91.21.00.03.5-19.0-0.40.2-4.2-2.011.0-63.0-2.6-11.9-1.71.41.7-5.1-1.0-5.0-22.71.2-0.7

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value39-5.4-8.3-9.4-34.7-18.69.7-37.4-10.8-16.6-38.5-48.2-11.3
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0-392.9-112.6100.0

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value-13.1111.21.5-8.02.0-2.51.5-2.05.5-1.7-8.13.8-0.62.23.83.0-6.6090.4880.1251.996-0.211-1.8471.17-5.388-3.893-2.9960.0460.506-4.030.986-2.9781.449-0.0910.984-0.36-0.383
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent-33.2-203.7-14.5-16.023.1-10.8-25.8-4.018.5-33.1-17.3-18.9-33.6-28.6-9.6-7.6-12.5-8.6-2.8-4.0-3.4-2.722.8-2.1-8.6-47.0-3.7-0.8-14.137.9-3.126.0-6.0-2.1-6.9-4.011.3

us-gaap:Parent


Other
Period End2021-03-312020-03-31
Value39-34.7
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax

us-gaap:ForeignExchangeForward, us-gaap:CashFlowHedging


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value33-33.4-22.9-6.126-12.930-3.914119.849-32.5
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateContract, us-gaap:CashFlowHedging


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1.00.30.1-5.4-47.36.9-7.1-24.6-14.2-23.27.23.18.1
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax3.0-0.9-0.488.5-181.9-53.5-23.3630.8-100.0-203.573.56.3-24.9

us-gaap:OtherNoncashIncomeExpense

us-gaap:OtherNoncashIncomeExpense


Other
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value-2800000.06200000.0-200000.03200000.0-13700000.0400000.001800000.0500000.0-1000000.016200000.0-7900000.0-5300000.0-8100000.05300000.0-2300000.0-2000000.0-10921000.010009000.0-8479000.0-609000.05599000.0-1237000.02623000.0-3027000.0-23128000.01391000.0-136000.0-173000.0-1863000.0-154000.02000.0-25000.0-862000.0-1000.00-17000.0206000.0
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:PaymentsForRestructuring

us-gaap:PaymentsForRestructuring


Payments
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value4.50.72.43.82.59.216212710.00.03.180.831.1064.88423242.6570.0
Percentage of PaymentsForRestructuring100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:PaymentsForRestructuring us-gaap:RestructuringCostAndReserve

us-gaap:EmployeeSeverance


Payments
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2.10.72.33.82.54.09.814168.00.00.6570.00.5373.8069.879231.8160.0
Percentage of PaymentsForRestructuring46.7100.095.8100.0100.043.560.970.658.080.00.020.70.048.677.942.994.068.30.0

us-gaap:OtherRestructuring


Payments
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2.40.00.10.00.05.26.36.2112.00.0-0.460.4950.3950.571.371.4670.8410.0
Percentage of PaymentsForRestructuring53.30.04.20.00.056.539.129.442.020.00.0-14.559.635.711.76.06.031.70.0

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.00.00.0192910410.011158270342
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt0.00.00.0100.0100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesGross us-gaap:BusinessAcquisition

us-gaap:PaymentsToAcquireBusinessesGross

alxn:PortolaPharmaceuticalsInc


Payments
Period End2020-07-02
Value1380
Percentage of PaymentsToAcquireBusinessesGross100.0

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired


Payments
Period End2020-12-312020-09-302020-06-302020-03-312016-12-312016-09-302015-12-312015-09-302014-12-312014-09-302013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value0.012740.08370.00.00.00.0390.00.00.00.00.00.00.00.00.3066050.00.00.481105
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired0.0100.00.0100.00.00.00.0100.00.00.00.00.00.00.00.00.0100.0100.00.00.0100.0100.0

us-gaap:PaymentsToAcquireIntangibleAssets

us-gaap:PaymentsToAcquireIntangibleAssets


Payments
Period End2021-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1100.08.00.08.00.00.00.00.0
Percentage of PaymentsToAcquireIntangibleAssets100.00.0100.00.0100.00.00.00.00.0

us-gaap:PaymentsToAcquireOtherInvestments

us-gaap:PaymentsToAcquireOtherInvestments


Payments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value0.00.03.6349.6190.043100.00.00.00.00.00.00.0120.00.0250.0
Percentage of PaymentsToAcquireOtherInvestments0.00.0100.0100.0100.0100.00.0100.0100.00.00.00.00.00.00.00.0100.00.00.0100.00.0

us-gaap:PaymentsToAcquireOtherInvestments us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

alxn:CaelumBiosciences


Payments
Period End2020-12-312020-09-302019-01-31
Value0.00.041
Percentage of PaymentsToAcquireOtherInvestments0.00.00.0

alxn:CaelumBiosciencesOption


Payments
Period End2020-12-31
Value-49.0
Percentage of PaymentsToAcquireOtherInvestments0.0

us-gaap:PaymentsToAcquireTradingSecuritiesHeldforinvestment

us-gaap:PaymentsToAcquireTradingSecuritiesHeldforinvestment


Payments
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-03-312012-12-31
Value7.05.64.62.66.94.22.55.15.83.11.52.35.21.93.31.73.01.8271.7521.3793.0422.7318.481.5332.2361.0190.6470.5461.2190.5120.00.0
Percentage of PaymentsToAcquireTradingSecuritiesHeldforinvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities


Proceeds
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value-1300000.0-1200000.0-10500000.0-16200000.0-1300000.0-1300000.0-1300000.0-1100000.0-1300000.0-10400000.0-5800000.0-600000.0-4100000.0-500000.0-500000.0-5900000.0-4000000.0-2675000.0-552000.0-681000.0-4092000.0-3038000.0-1105000.0-310000.0-303000.0-142000.0-38000.0-39000.0-42000.0-87000.0-34000.0-39000.0-60000.0-127000.0-351000.0-196000.0-91000.0
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities

us-gaap:ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-30
Value0.01724141117146921173018991551573742752822321912426966628541762211221769932252.0020.00.00.0
Percentage of ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities

us-gaap:ProceedsFromSaleAndMaturityOfMarketableSecurities


Proceeds
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-09-302012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-06-302010-03-31
Value3.32.54.32.03.33.32.45.33.73.03.43.12.83.60.00.00.00.07.3581339350.05.25
Percentage of ProceedsFromSaleAndMaturityOfMarketableSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.00.0100.0

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProceedsFromStockOptionsExercised


Proceeds
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value15369.2102.86.72.710105.916159.49.91513479.248.165163.43331196.80224362521302620149.52711241415117.985
Percentage of ProceedsFromStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax


Reclassification
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-31
Value-17.9-18.1-12.8-0.35.28.011109.0105.52.9-9.6-2.6-0.89.89.0128.354101416262726134.618-0.7730.885.077
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterest


Reclassification
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-17.9-12.8-0.35.211109.05.61.2-9.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0101.841.493.8

us-gaap:RepaymentsOfDebt dei:LegalEntity, us-gaap:CounterpartyName, us-gaap:DebtInstrument

us-gaap:RepaymentsOfDebt

alxn:PortolaPharmaceuticalsInc, alxn:HealthCareRoyaltyPartners, alxn:RoyaltyBasedFinancingAgreement


Repayments
Period End2020-07-02
Value13
Percentage of RepaymentsOfDebt100.0

us-gaap:RepaymentsOfDebt us-gaap:BusinessAcquisition

alxn:PortolaPharmaceuticalsInc


Repayments
Period End2020-07-02
Value196
Percentage of RepaymentsOfDebt1437.2

us-gaap:RepaymentsOfDebt us-gaap:CounterpartyName, us-gaap:DebtInstrument

alxn:HealthCareRoyaltyPartners, alxn:RoyaltyBasedFinancingAgreement


Repayments
Period End2021-03-312020-09-30
Value3.31.7
Percentage of RepaymentsOfDebt0.00.0

us-gaap:RepaymentsOfDebt us-gaap:CounterpartyName, us-gaap:StatementScenario, us-gaap:DebtInstrument

alxn:HealthCareRoyaltyPartners, srt:ScenarioForecast, alxn:RoyaltyBasedFinancingAgreement


Repayments
Period End2021-06-302021-03-312020-12-31
Value2.53.03.0
Percentage of RepaymentsOfDebt0.00.00.0

us-gaap:ResearchAndDevelopmentAssetAcquiredOtherThanThroughBusinessCombinationWrittenOff

us-gaap:ResearchAndDevelopmentAssetAcquiredOtherThanThroughBusinessCombinationWrittenOff


Research
Period End2021-03-312020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302018-06-302017-12-312017-09-302017-06-30
Value1930.00.00.0-4.13790.08030.00.00.0
Percentage of ResearchAndDevelopmentAssetAcquiredOtherThanThroughBusinessCombinationWrittenOff100.00.00.00.0100.0100.00.0100.00.00.00.0

us-gaap:RestructuringAndRelatedCostIncurredCost

us-gaap:RestructuringAndRelatedCostIncurredCost


Restructuring
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-30
Value2.414-0.13.15.38.92.7161894166
Percentage of RestructuringAndRelatedCostIncurredCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RestructuringAndRelatedCostIncurredCost us-gaap:RestructuringCostAndReserve

us-gaap:EmployeeSeverance


Restructuring
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-30
Value0.0140.00.05.38.9-0.11.13.90.267
Percentage of RestructuringAndRelatedCostIncurredCost0.0100.0-0.00.0100.0100.0-3.76.921.20.240.4

us-gaap:RestructuringCharges

us-gaap:RestructuringCharges


Restructuring
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-3.2140.10.32.59.1791817140.01642.9241.5090.5640.4750.452125.181154.378
Percentage of RestructuringCharges100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RestructuringCharges us-gaap:RestructuringCostAndReserve

us-gaap:EmployeeSeverance


Restructuring
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-5.614-0.3-2.82.49.1-2.32.83.11.00.366-0.6210.00.00.00.00.3952.518144.287
Percentage of RestructuringCharges175.0100.0-300.0-933.396.0100.0-2.915.417.66.90.040.2-20.787.50.00.00.00.03.148.693.397.9

us-gaap:OtherRestructuring


Restructuring
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2.40.43.10.10.01.47.57.54.45.98.03.53.0-0.4560.5640.4750.4171.0951.6341.0270.091
Percentage of RestructuringCharges-75.0400.01033.34.00.01.841.242.630.60.04.9120.712.5-30.2100.0100.092.38.531.56.72.1

us-gaap:RestructuringCosts

us-gaap:RestructuringCosts


Restructuring
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-06-30
Value3.75745-0.5100.0
Percentage of RestructuringCosts100.0100.0100.0100.0100.00.0

us-gaap:RestructuringReserveAccrualAdjustment1

us-gaap:RestructuringReserveAccrualAdjustment1


Restructuring
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-31
Value-5600000.0200000.0-2800000.0-2800000.0200000.0-2200000.02200000.0-800000.01100000.0-2000000.00
Percentage of RestructuringReserveAccrualAdjustment1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

us-gaap:RestructuringReserveAccrualAdjustment1 us-gaap:RestructuringCostAndReserve

us-gaap:EmployeeSeverance


Restructuring
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-31
Value-5600000.0-400000.0-2800000.0-2800000.0200000.0-2200000.01700000.0-800000.0100000.0-1000000.00
Percentage of RestructuringReserveAccrualAdjustment1100.0-200.0100.0100.0100.0100.077.3100.09.150.00.0

us-gaap:OtherRestructuring


Restructuring
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-31
Value0600000.00000500000.001000000.0-1000000.00
Percentage of RestructuringReserveAccrualAdjustment1-0.0300.0-0.0-0.00.0-0.022.7-0.090.950.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost


Share
Period End2020-12-312020-09-302020-06-302020-03-312019-06-30
Value36110.0250.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost100.0100.00.0100.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost us-gaap:BusinessAcquisition

alxn:Achillion


Share
Period End2020-12-312020-09-302020-06-302020-01-282020-03-31
Value0.00.00.02025
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost0.00.00.0100.00.0

alxn:PortolaPharmaceuticalsInc


Share
Period End2020-07-02
Value11
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost0.0

us-gaap:StockIssued1

us-gaap:StockIssued1


Stock
Period End2020-12-312015-12-312014-12-312013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value0.00.00.00.00.00.00.00.00.7180.00.03.0120.0
Percentage of StockIssued10.00.00.00.00.00.00.00.0100.00.00.0100.00.0

us-gaap:StockIssuedDuringPeriodSharesRestrictedStockAwardGross us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesRestrictedStockAwardGross

us-gaap:CommonStock


Stock
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1300000.0700000.0300000.0200000.01000000.0200000.0100000.0200000.0700000.0300000.0100000.0100000.0800000.0
Percentage of StockIssuedDuringPeriodSharesRestrictedStockAwardGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:CommonStock


Stock
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value100000.0500000.0200000.0100000.0100000.0100000.0100000.0100000.0100000.0100000.0200000.0200000.0100000.0
Percentage of StockIssuedDuringPeriodSharesStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueAcquisitions

us-gaap:StockIssuedDuringPeriodValueAcquisitions


Stock
Period End2020-12-312020-09-30
Value07200000.0
Percentage of StockIssuedDuringPeriodValueAcquisitions0.0100.0

us-gaap:StockIssuedDuringPeriodValueAcquisitions us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2020-12-312020-09-30
Value07200000.0
Percentage of StockIssuedDuringPeriodValueAcquisitions0.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised


Stock
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value143610102.86.71.911106.216159.5
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value143610102.86.71.911106.216159.5
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Parent


Stock
Period End2021-03-312020-03-31
Value142.8
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0

us-gaap:TreasuryStockSharesAcquired

us-gaap:TreasuryStockSharesAcquired


Treasury
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-03-312012-12-31
Value700000.0600000.02300000.01300000.0300000.03100000.0300000.0100000.000700000.0500000.01600000.01000000.0536000.0245000.02083000.0556000.0132000.0334000.0640000.01012000.0137000.0405000.0130000.0
Percentage of TreasuryStockSharesAcquired100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TreasuryStockSharesAcquired us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType

us-gaap:CommonStock, us-gaap:SubsequentEvent


Treasury
Period End2020-10-29
Value400000.0
Percentage of TreasuryStockSharesAcquired0.0

us-gaap:TreasuryStockSharesAcquired us-gaap:StatementEquityComponents

us-gaap:TreasuryStock


Treasury
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value700000.0600000.02300000.01300000.0300000.03100000.0300000.0100000.0000700000.0
Percentage of TreasuryStockSharesAcquired100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0

us-gaap:TreasuryStockValueAcquiredCostMethod

us-gaap:TreasuryStockValueAcquiredCostMethod


Treasury
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-03-312012-12-31
Value76732531073233437110.00.00.085164601706830693429615291236019104156223511
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TreasuryStockValueAcquiredCostMethod us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType

us-gaap:CommonStock, us-gaap:SubsequentEvent


Treasury
Period End2020-10-29
Value45
Percentage of TreasuryStockValueAcquiredCostMethod0.0

us-gaap:TreasuryStockValueAcquiredCostMethod us-gaap:StatementEquityComponents

us-gaap:TreasuryStock


Treasury
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value76732531073233437110.00.00.085
Percentage of TreasuryStockValueAcquiredCostMethod100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0

us-gaap:UnrealizedGainLossOnInvestments

us-gaap:UnrealizedGainLossOnInvestments


Unrealized
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-03-312015-03-31
Value-9.6-7.6-21.235-9.26.312-25.233-60.30.00.01000.00.011-11.0-17.0980.434
Percentage of UnrealizedGainLossOnInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.00.00.0100.0100.0100.0100.0

us-gaap:UnrealizedGainLossOnInvestments us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

alxn:Dicerna


Unrealized
Period End2021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value3.0-6.25.9-3.16.4-1.10.93.31.4
Percentage of UnrealizedGainLossOnInvestments-31.229.216.933.7101.6-9.2-3.69.8-2.3

alxn:EidosMember


Unrealized
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value-9.8453.40.6-3.75.02.9
Percentage of UnrealizedGainLossOnInvestments102.1-593.4-16.01.740.279.424.2

alxn:Inozyme


Unrealized
Period End2021-03-312020-12-312020-09-30
Value1.5-4.510
Percentage of UnrealizedGainLossOnInvestments-15.659.2-48.1

alxn:PortolaPharmaceuticals


Unrealized
Period End2020-09-302020-06-302020-03-31
Value-0.1290.6
Percentage of UnrealizedGainLossOnInvestments0.582.9-6.5

alxn:Stealth


Unrealized
Period End2020-12-312020-09-302020-06-302019-12-31
Value0.2-0.70.9-5.2
Percentage of UnrealizedGainLossOnInvestments-2.63.32.6-82.5

alxn:Zealand


Unrealized
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-2.5-2.71.8-0.8-0.27.43.72.90.7
Percentage of UnrealizedGainLossOnInvestments26.035.5-8.5-2.32.2117.530.8-11.52.1

alxn:AccruedClinicalExpensesPayableCurrent

alxn:AccruedClinicalExpensesPayableCurrent


Accrued
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value9767587964563017
Percentage of AccruedClinicalExpensesPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0

alxn:AccruedManufacturingPayableCurrent

alxn:AccruedManufacturingPayableCurrent


Accrued
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value587272415219427.25
Percentage of AccruedManufacturingPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0

alxn:AccruedRebatesPayable

alxn:AccruedRebatesPayable


Accrued
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value3332501229970553612462214.66
Percentage of AccruedRebatesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:AssetSaleContingentPaymentsToBeReceived us-gaap:CounterpartyName

alxn:AssetSaleContingentPaymentsToBeReceived

alxn:OriginBiosciences


Asset
Period End2021-03-31
Value21
Percentage of AssetSaleContingentPaymentsToBeReceived100.0

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLongTermDebt us-gaap:BusinessAcquisition

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLongTermDebt

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value182
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLongTermDebt100.0

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsInventory us-gaap:BusinessAcquisition

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsInventory

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value169
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsInventory100.0

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsAndLiabilitiesNet us-gaap:ConsolidatedEntities

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsAndLiabilitiesNet

us-gaap:VariableInterestEntityPrimaryBeneficiary


Business
Period End2021-03-31
Value6800000.0
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherAssetsAndLiabilitiesNet100.0

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherLiabilities us-gaap:BusinessAcquisition

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherLiabilities

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value24
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherLiabilities100.0

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedValidationBatches us-gaap:BusinessAcquisition

alxn:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedValidationBatches

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value60
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedValidationBatches100.0

alxn:ComputerHardwareAndSoftware

alxn:ComputerHardwareAndSoftware


Computer
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value171155144141123835941332720
Percentage of ComputerHardwareAndSoftware100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:DeferredTaxAssetsAccruedRoyalties

alxn:DeferredTaxAssetsAccruedRoyalties


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1.20.8897423154114
Percentage of DeferredTaxAssetsAccruedRoyalties100.0100.0100.0100.0100.0100.0100.0100.0

alxn:DeferredTaxAssetsLongTermDebt us-gaap:BusinessAcquisition

alxn:DeferredTaxAssetsLongTermDebt

alxn:PortolaPharmaceuticalsInc


Deferred
Period End2020-07-02
Value42400.0
Percentage of DeferredTaxAssetsLongTermDebt100.0

alxn:DeferredTaxAssetsRightOfUseLeases

alxn:DeferredTaxAssetsRightOfUseLeases


Deferred
Period End2020-12-312019-12-312018-12-31
Value45460.0
Percentage of DeferredTaxAssetsRightOfUseLeases100.0100.00.0

alxn:DeferredTaxLiabilitiesInvestmentinPartnerships

alxn:DeferredTaxLiabilitiesInvestmentinPartnerships


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value19922249566607546409116100
Percentage of DeferredTaxLiabilitiesInvestmentinPartnerships100.0100.0100.0100.0100.0100.0100.0100.0

alxn:DerivativeNotionalAmount1 us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

alxn:DerivativeNotionalAmount1

alxn:ForeignExchangeForwardOpenExpense, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-09-302020-06-302019-09-30
Value10.01115
Percentage of DerivativeNotionalAmount1100.0100.0100.0

us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-09-302020-06-302019-09-30
Value85310298021211
Percentage of DerivativeNotionalAmount10.010290.07098.27768.6

us-gaap:ForeignExchangeForward, us-gaap:Nondesignated


Derivative
Period End2021-03-312020-09-302020-06-302019-09-30
Value1126125319361103
Percentage of DerivativeNotionalAmount10.012530.017136.37071.8

alxn:EquityMethodInvestmentDerecognizedAmount us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

alxn:EquityMethodInvestmentDerecognizedAmount

alxn:CaelumBiosciences


Equity
Period End2021-03-31
Value41
Percentage of EquityMethodInvestmentDerecognizedAmount100.0

alxn:GoodwillAccumulatedAmortization

alxn:GoodwillAccumulatedAmortization


Goodwill
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value2900000.02900000.02900000.02900000.02900000.02900000.02900000.02900000.02900000.02900000.02900000.02900000.03000000.03000000.03000000.02901000.02901000.02901000.02901000.02901000.02901000.02901000.02901000.02901000.02901000.0
Percentage of GoodwillAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:IndefiniteLivedIntangibleAssetsGrossExcludingGoodwill us-gaap:IndefiniteLivedIntangibleAssetsByMajorClass

alxn:IndefiniteLivedIntangibleAssetsGrossExcludingGoodwill

alxn:AcquiredIprd


Indefinite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-31
Value9229229229070.0
Percentage of IndefiniteLivedIntangibleAssetsGrossExcludingGoodwill100.0100.0100.0100.00.0

alxn:PriorityReviewVoucher


Indefinite
Period End2021-03-31
Value100
Percentage of IndefiniteLivedIntangibleAssetsGrossExcludingGoodwill10.8

alxn:IntangibleAssetsAccumulatedAmortization

alxn:IntangibleAssetsAccumulatedAmortization


Intangible
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value3788373436793625143413581280119911191038958798719559479397315235155753827201511
Percentage of IntangibleAssetsAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:IntangibleAssetsCost

alxn:IntangibleAssetsCost


Intangible
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value6836673667365685477847684768476047604752475247524751478247824865486348634863486362663766710636
Percentage of IntangibleAssetsCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

alxn:InventoryCurrent

alxn:InventoryCurrent


Inventory
Period End2021-03-312020-12-312020-09-302019-12-31
Value803775729627
Percentage of InventoryCurrent100.0100.0100.0100.0

alxn:LeaseWeightedAverageDiscountRate

alxn:LeaseWeightedAverageDiscountRate


Lease
Period End2020-12-312019-12-31
Value3.84.3
Percentage of LeaseWeightedAverageDiscountRate100.0100.0

alxn:LesseeLeaseLiability

alxn:LesseeLeaseLiability


Lessee
Period End2020-12-312019-12-31
Value278261
Percentage of LesseeLeaseLiability100.0100.0

alxn:LesseeLeaseLiabilityPaymentsDue

alxn:LesseeLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-312019-12-31
Value329323
Percentage of LesseeLeaseLiabilityPaymentsDue100.0100.0

alxn:LesseeLeaseLiabilityPaymentsDueAfterYearFive

alxn:LesseeLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value148
Percentage of LesseeLeaseLiabilityPaymentsDueAfterYearFive100.0

alxn:LesseeLeaseLiabilityPaymentsDueNextTwelveMonths

alxn:LesseeLeaseLiabilityPaymentsDueNextTwelveMonths


Lessee
Period End2020-12-31
Value43
Percentage of LesseeLeaseLiabilityPaymentsDueNextTwelveMonths100.0

alxn:LesseeLeaseLiabilityPaymentsDueYearFive

alxn:LesseeLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value30
Percentage of LesseeLeaseLiabilityPaymentsDueYearFive100.0

alxn:LesseeLeaseLiabilityPaymentsDueYearFour

alxn:LesseeLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-31
Value31
Percentage of LesseeLeaseLiabilityPaymentsDueYearFour100.0

alxn:LesseeLeaseLiabilityPaymentsDueYearThree

alxn:LesseeLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-31
Value34
Percentage of LesseeLeaseLiabilityPaymentsDueYearThree100.0

alxn:LesseeLeaseLiabilityPaymentsDueYearTwo

alxn:LesseeLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-31
Value41
Percentage of LesseeLeaseLiabilityPaymentsDueYearTwo100.0

alxn:LesseeLeaseLiabilityUndiscountedExcessAmount

alxn:LesseeLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-312019-12-31
Value5162
Percentage of LesseeLeaseLiabilityUndiscountedExcessAmount100.0100.0

alxn:OperatingLossCarryforwardsNotSubjectToExpiration us-gaap:IncomeTaxAuthority

alxn:OperatingLossCarryforwardsNotSubjectToExpiration

us-gaap:DomesticCountry


Operating
Period End2020-12-31
Value112
Percentage of OperatingLossCarryforwardsNotSubjectToExpiration100.0

us-gaap:StateAndLocalJurisdiction


Operating
Period End2020-12-31
Value1.9
Percentage of OperatingLossCarryforwardsNotSubjectToExpiration1.7

alxn:OtherInvestmentsDerecognizedAmount us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

alxn:OtherInvestmentsDerecognizedAmount

alxn:CaelumBiosciencesOption


Other
Period End2021-03-31
Value15
Percentage of OtherInvestmentsDerecognizedAmount100.0

alxn:ResearchandDevelopmentArrangementPotentialPaymentMaximum us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

alxn:ResearchandDevelopmentArrangementPotentialPaymentMaximum

alxn:Dicerna, alxn:DicernaPharmaceuticalCollaborationAgreement


Researchand
Period End2021-03-312020-12-312020-09-302020-06-302019-12-31
Value604604604606629
Percentage of ResearchandDevelopmentArrangementPotentialPaymentMaximum100.0100.0100.0100.0100.0

alxn:HalozymeTherapeuticsInc, alxn:LicenseAgreement1


Researchand
Period End2021-03-312020-12-312020-09-302020-06-302019-12-31
Value155155155155160
Percentage of ResearchandDevelopmentArrangementPotentialPaymentMaximum25.725.725.725.625.4

alxn:RoyaltyAgreementRemainingRoyaltyPaymentsToBePaid us-gaap:CounterpartyName, us-gaap:BusinessAcquisition, us-gaap:DebtInstrument

alxn:RoyaltyAgreementRemainingRoyaltyPaymentsToBePaid

alxn:HealthCareRoyaltyPartners, alxn:PortolaPharmaceuticalsInc, alxn:RoyaltyBasedFinancingAgreement


Royalty
Period End2020-12-312020-07-02
Value271276
Percentage of RoyaltyAgreementRemainingRoyaltyPaymentsToBePaid100.0100.0

alxn:TaxCreditCarryforwardNotSubjectToExpiration us-gaap:IncomeTaxAuthority

alxn:TaxCreditCarryforwardNotSubjectToExpiration

us-gaap:StateAndLocalJurisdiction


Tax
Period End2020-12-31
Value31
Percentage of TaxCreditCarryforwardNotSubjectToExpiration100.0

alxn:TaxCreditCarryforwardSubjectToExpiration us-gaap:IncomeTaxAuthority

alxn:TaxCreditCarryforwardSubjectToExpiration

us-gaap:StateAndLocalJurisdiction


Tax
Period End2020-12-31
Value51
Percentage of TaxCreditCarryforwardSubjectToExpiration100.0

alxn:UnrecordedUnconditionalPurchaseObligationUndiscountedFixedPaymentAmount us-gaap:CounterpartyName

alxn:UnrecordedUnconditionalPurchaseObligationUndiscountedFixedPaymentAmount

alxn:LonzaGroupAG


Unrecorded
Period End2021-03-312020-12-312020-09-30
Value97100105
Percentage of UnrecordedUnconditionalPurchaseObligationUndiscountedFixedPaymentAmount100.0100.0100.0

us-gaap:AccountsPayableCurrentAndNoncurrent

us-gaap:AccountsPayableCurrentAndNoncurrent


Accounts
Period End2020-12-312019-12-312018-12-312017-12-31
Value118747470
Percentage of AccountsPayableCurrentAndNoncurrent100.0100.0100.0100.0

us-gaap:AccruedRoyaltiesCurrent

us-gaap:AccruedRoyaltiesCurrent


Accrued
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312010-12-31
Value27202722202925402555102928250
Percentage of AccruedRoyaltiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BuildingsAndImprovementsGross

us-gaap:BuildingsAndImprovementsGross


Buildings
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value216208520427450252170154147141133
Percentage of BuildingsAndImprovementsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh

us-gaap:BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh


Business
Period End2021-03-312020-12-312020-09-302014-12-31
Value905905905876
Percentage of BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh100.0100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiability

us-gaap:BusinessCombinationContingentConsiderationLiability


Business
Period End2020-12-312020-06-302019-12-312018-12-312017-12-312017-03-312016-12-312016-03-312015-12-312015-03-312014-12-312013-12-31
Value299374192183168132129107121126116106
Percentage of BusinessCombinationContingentConsiderationLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiability us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

alxn:ContingentConsideration, us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Business
Period End2020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value398374192188158154183179156168160132129126109107121158129126116106106
Percentage of BusinessCombinationContingentConsiderationLiability0.0100.0100.00.00.00.0100.00.00.0100.00.0100.0100.00.00.0100.0100.00.00.0100.0100.00.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiability us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

alxn:ContingentConsideration, alxn:AcquisitionRelatedContingentConsideration


Business
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value423414398374192188158154183179156168160132129126109107121158129126116106106
Percentage of BusinessCombinationContingentConsiderationLiability0.0138.40.0100.0100.00.00.00.0100.00.00.0100.00.0100.0100.00.00.0100.0100.00.00.0100.0100.00.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent


Business
Period End2021-03-312020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302015-12-31
Value1201140.00.0100979795700.00.025248155
Percentage of BusinessCombinationContingentConsiderationLiabilityCurrent100.0100.00.00.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

alxn:CurrentContingentConsideration, us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Business
Period End2021-03-312020-12-31
Value120114
Percentage of BusinessCombinationContingentConsiderationLiabilityCurrent100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityCurrent us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

alxn:CurrentContingentConsideration, alxn:AcquisitionRelatedContingentConsideration


Business
Period End2021-03-312020-12-31
Value120114
Percentage of BusinessCombinationContingentConsiderationLiabilityCurrent100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent


Business
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302016-12-312016-09-302016-06-302015-12-312015-09-302015-06-302014-12-31
Value303299398374192188158154183179156342160129126109121158129116
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

alxn:ContingentConsideration, us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Business
Period End2021-03-312020-12-312019-12-31
Value303299192
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

alxn:ContingentConsideration, alxn:AcquisitionRelatedContingentConsideration


Business
Period End2021-03-312020-12-312019-12-31
Value303299192
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent100.0100.0100.0

us-gaap:BusinessCombinationContingentConsiderationLiabilityNoncurrent us-gaap:BusinessAcquisition

alxn:Achillion


Business
Period End2021-03-312020-12-312020-09-302020-06-302020-01-28
Value212210209190160
Percentage of BusinessCombinationContingentConsiderationLiabilityNoncurrent70.170.352.650.70.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value288
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Business
Period End2021-03-31
Value16
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents0.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value17
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value75
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value7700000.0
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value116
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets us-gaap:ConsolidatedEntities

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets

us-gaap:VariableInterestEntityPrimaryBeneficiary


Business
Period End2021-03-31
Value193
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value1051
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles us-gaap:BusinessAcquisition, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles

alxn:PortolaPharmaceuticalsInc, alxn:PurchasedTechnology


Business
Period End2020-07-02
Value1036
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value362
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value1621
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet100.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Business
Period End2021-03-31
Value217
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet0.0

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets

alxn:PortolaPharmaceuticalsInc


Business
Period End2020-07-02
Value41
Percentage of BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets100.0

us-gaap:CapitalizedComputerSoftwareAccumulatedAmortization

us-gaap:CapitalizedComputerSoftwareAccumulatedAmortization


Capitalized
Period End2020-12-312019-12-31
Value8772
Percentage of CapitalizedComputerSoftwareAccumulatedAmortization100.0100.0

us-gaap:CapitalizedComputerSoftwareGross

us-gaap:CapitalizedComputerSoftwareGross


Capitalized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value535350583719169.6919.628107.368
Percentage of CapitalizedComputerSoftwareGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass

us-gaap:CashAndCashEquivalentsFairValueDisclosure

us-gaap:CashEquivalents, us-gaap:MoneyMarketFunds


Cash
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value125883342412126355294985455695035.432266832782179133605192176236234717813853803
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:CashEquivalents, us-gaap:MoneyMarketFunds, us-gaap:FairValueInputsLevel2


Cash
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value125883342412126355294985455695035.432266832782179133605192176236234717813853803
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerAssetNetCurrent

us-gaap:ContractWithCustomerAssetNetCurrent


Contract
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value14731409143713721243111611231016922910853726
Percentage of ContractWithCustomerAssetNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentInterestRateEffectivePercentage us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentInterestRateEffectivePercentage

alxn:CreditAgreement, us-gaap:LineOfCredit


Debt
Period End2020-12-31
Value1.4
Percentage of DebtInstrumentInterestRateEffectivePercentage100.0

us-gaap:DebtInstrumentUnamortizedDiscount us-gaap:CounterpartyName, us-gaap:BusinessAcquisition, us-gaap:DebtInstrument

us-gaap:DebtInstrumentUnamortizedDiscount

alxn:HealthCareRoyaltyPartners, alxn:PortolaPharmaceuticalsInc, alxn:RoyaltyBasedFinancingAgreement


Debt
Period End2020-07-02
Value94
Percentage of DebtInstrumentUnamortizedDiscount100.0

us-gaap:DeferredFinanceCostsNet

us-gaap:DeferredFinanceCostsNet


Deferred
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value9.91112131517181920222321
Percentage of DeferredFinanceCostsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxAssetsNet


Deferred
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312018-12-31
Value21402199227023322290101
Percentage of DeferredIncomeTaxAssetsNet100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value2103230893096811871082202
Percentage of DeferredIncomeTaxLiabilities100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsDerivativeInstruments

us-gaap:DeferredTaxAssetsDerivativeInstruments


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value25180.06.60.0
Percentage of DeferredTaxAssetsDerivativeInstruments100.0100.00.0100.00.0

us-gaap:DeferredTaxAssetsGoodwillAndIntangibleAssets

us-gaap:DeferredTaxAssetsGoodwillAndIntangibleAssets


Deferred
Period End2020-12-312019-12-312018-12-312012-12-312011-12-31
Value189219670.00.6390.0
Percentage of DeferredTaxAssetsGoodwillAndIntangibleAssets100.0100.00.0100.00.0

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsGross


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value294625896616998135712548764181214
Percentage of DeferredTaxAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsInProcessResearchAndDevelopment

us-gaap:DeferredTaxAssetsInProcessResearchAndDevelopment


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1.93.55.27.215191293.418
Percentage of DeferredTaxAssetsInProcessResearchAndDevelopment100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value318102414.9581683.4015.3988.51954126
Percentage of DeferredTaxAssetsOperatingLossCarryforwards100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards us-gaap:BusinessAcquisition

alxn:PortolaPharmaceuticalsInc


Deferred
Period End2020-07-02
Value0.301
Percentage of DeferredTaxAssetsOperatingLossCarryforwards0.0

us-gaap:DeferredTaxAssetsOther us-gaap:BusinessAcquisition

us-gaap:DeferredTaxAssetsOther

alxn:PortolaPharmaceuticalsInc


Deferred
Period End2020-07-02
Value39100.0
Percentage of DeferredTaxAssetsOther100.0

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value4653283714425372091.7064.8639.2796435
Percentage of DeferredTaxAssetsTaxCreditCarryforwards100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards us-gaap:BusinessAcquisition

alxn:PortolaPharmaceuticalsInc


Deferred
Period End2020-07-02
Value0.042
Percentage of DeferredTaxAssetsTaxCreditCarryforwards0.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value5857476689734933252216
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value138651059791852926214028
Percentage of DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts


Deferred
Period End2020-12-31
Value53
Percentage of DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts us-gaap:BusinessAcquisition

alxn:PortolaPharmaceuticalsInc


Deferred
Period End2020-07-02
Value0.0634
Percentage of DeferredTaxLiabilitiesDeferredExpenseCapitalizedInventoryCosts0.0

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets us-gaap:BusinessAcquisition

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

alxn:PortolaPharmaceuticalsInc


Deferred
Period End2020-07-02
Value0.2451
Percentage of DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets100.0

us-gaap:DeferredTaxLiabilitiesLeasingArrangements

us-gaap:DeferredTaxLiabilitiesLeasingArrangements


Deferred
Period End2020-12-312019-12-312018-12-31
Value51530.0
Percentage of DeferredTaxLiabilitiesLeasingArrangements100.0100.00.0

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value5.65.1887595824041414037
Percentage of DeferredTaxLiabilitiesPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeCollateralObligationToReturnSecurities us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeCollateralObligationToReturnSecurities

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value212611232111241830161326272316494227109.4988.420.4020.882127
Percentage of DerivativeCollateralObligationToReturnSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeCollateralRightToReclaimSecurities us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeCollateralRightToReclaimSecurities

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value212611232111241830161326272316494227109.4988.420.4020.882127
Percentage of DerivativeCollateralRightToReclaimSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeAsset

us-gaap:DerivativeFairValueOfDerivativeAsset


Derivative
Period End2021-03-312020-12-312020-09-302019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312011-06-302010-12-31
Value4126123060481661581363127252.7469.955
Percentage of DerivativeFairValueOfDerivativeAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeAsset us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:OtherNoncurrentAssets, us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value0.10.40.00.64.11.11.70.30.71.94.17.04359314435666982125586.3629.839
Percentage of DerivativeFairValueOfDerivativeAsset0.23.30.02.00.00.00.00.50.00.08.40.00.035.50.00.00.042.00.00.00.043.10.031.1

us-gaap:PrepaidExpensesAndOtherCurrentAssets, us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302015-12-31
Value193.01412321219161616121761804885
Percentage of DerivativeFairValueOfDerivativeAsset46.224.80.041.60.00.00.027.80.00.026.40.00.048.20.053.8

us-gaap:DerivativeFairValueOfDerivativeAsset us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:InvestmentType

us-gaap:PrepaidExpensesAndOtherCurrentAssets, us-gaap:ForeignExchangeForward, us-gaap:Nondesignated, us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302019-12-31
Value22268.717
Percentage of DerivativeFairValueOfDerivativeAsset53.6100.071.956.4

us-gaap:DerivativeFairValueOfDerivativeAsset us-gaap:DerivativeInstrumentRisk

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value41261243304935466064494842120166811079315814817124113624312642492719322025
Percentage of DerivativeFairValueOfDerivativeAsset100.0100.0100.00.0100.00.00.00.0100.00.00.0100.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.00.00.00.0100.00.00.00.0100.0

us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302012-12-31
Value4126124330493546606449484212016681107931581481712411362431264227
Percentage of DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302012-12-31
Value200.7209.13710283047362215971503264651471391632411353.2024.3987.0133617
Percentage of DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeLiability

us-gaap:DerivativeFairValueOfDerivativeLiability


Derivative
Period End2021-03-312020-12-312020-09-302019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312011-06-302010-12-31
Value10017212889407416100.883510102115
Percentage of DerivativeFairValueOfDerivativeLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeLiability us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:OtherCurrentLiabilities, us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value9.444163.66.23.67.62.47.310.01534327.02.02521151.4913.1842.9340.3360.7942120
Percentage of DerivativeFairValueOfDerivativeLiability9.425.713.10.07.00.00.00.018.20.00.046.70.00.012.50.00.00.014.30.00.00.090.20.057.6

us-gaap:OtherCurrentLiabilities, us-gaap:InterestRateContract, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-30
Value454545451916102.90.80.00.00.01.00.00.00.9461.01
Percentage of DerivativeFairValueOfDerivativeLiability45.626.635.50.021.90.00.00.02.00.00.00.00.00.00.00.00.0

us-gaap:OtherNoncurrentLiabilities, us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value1.20.30.41.10.81.80.93.15.89.926289.04.03836304.7735.8065.4860.0660.0861314
Percentage of DerivativeFairValueOfDerivativeLiability0.70.20.01.20.00.00.07.80.00.034.90.00.025.00.00.00.045.80.00.00.09.80.042.4

us-gaap:OtherNoncurrentLiabilities, us-gaap:InterestRateContract, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-30
Value3245576941555231170.00.00.01.00.00.00.7974.813
Percentage of DerivativeFairValueOfDerivativeLiability32.826.344.90.047.00.00.00.043.20.00.00.00.00.00.00.00.0

us-gaap:DerivativeFairValueOfDerivativeLiability us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation, us-gaap:InvestmentType

us-gaap:OtherCurrentLiabilities, us-gaap:ForeignExchangeForward, us-gaap:Nondesignated, us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302019-12-31
Value12358.020
Percentage of DerivativeFairValueOfDerivativeLiability12.220.76.222.9

us-gaap:DerivativeFairValueOfDerivativeLiability us-gaap:DerivativeInstrumentRisk

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-31
Value1001721281398990874240192674672316757262109.4988.420.4020.883435245.7862.74910126.8553.64810
Percentage of DerivativeFairValueOfDerivativeLiability100.0100.0100.00.0100.00.00.00.0100.00.00.0100.00.00.0100.00.00.00.0100.00.00.00.0100.00.0100.00.00.00.0100.00.00.00.0100.0

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302012-12-31
Value1001721281398990874240192674672316757262109.4988.420.4020.883435245.78610
Percentage of DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral

us-gaap:ForeignExchangeForward


Derivative
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302013-06-302012-12-31
Value78146116116677863249.83.01348400.00.02529340.00.00.00.00.0127.8364.9380.00.0
Percentage of DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.00.00.00.00.00.0100.0100.0100.00.00.0

us-gaap:DerivativeFixedInterestRate us-gaap:Range, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:DerivativeFixedInterestRate

srt:Maximum, alxn:InterestRateSwapFour, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-312020-06-302019-12-312019-09-302019-06-302019-03-31
Value2.830.0002830.02830.02830.02830.0283
Percentage of DerivativeFixedInterestRate100.0100.0100.0100.0100.0100.0

srt:Maximum, alxn:InterestRateSwapTwo, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-312020-06-302019-12-312019-09-30
Value2.790.0002790.02790.0279
Percentage of DerivativeFixedInterestRate98.698.698.698.6

srt:Minimum, alxn:InterestRateSwapFour, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-312020-06-302019-12-312019-09-302019-06-302019-03-31
Value2.370.0002370.02370.02370.02790.0279
Percentage of DerivativeFixedInterestRate83.783.783.783.798.698.6

srt:Minimum, alxn:InterestRateSwapTwo, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-312020-06-302019-12-312019-09-30
Value2.60.000260.0260.026
Percentage of DerivativeFixedInterestRate91.991.991.991.9

us-gaap:DerivativeNotionalAmount us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation

us-gaap:DerivativeNotionalAmount

alxn:ForeignExchangeForwardOpenExpense, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-31
Value8.7
Percentage of DerivativeNotionalAmount100.0

alxn:InterestRateSwapFour, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-31
Value1300
Percentage of DerivativeNotionalAmount14942.5

alxn:InterestRateSwapTwo, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-31
Value450
Percentage of DerivativeNotionalAmount5172.4

us-gaap:ForeignExchangeForward, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2020-12-31
Value1174
Percentage of DerivativeNotionalAmount13502.3

us-gaap:ForeignExchangeForward, us-gaap:Nondesignated


Derivative
Period End2020-12-31
Value2070
Percentage of DerivativeNotionalAmount23794.3

us-gaap:EmployeeRelatedLiabilitiesCurrent

us-gaap:EmployeeRelatedLiabilitiesCurrent


Employee
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value2421911701491211158864493924
Percentage of EmployeeRelatedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized


Employee
Period End2020-12-31
Value366
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized100.0

us-gaap:EscrowDeposit us-gaap:LitigationCase, us-gaap:SubsequentEventType

us-gaap:EscrowDeposit

alxn:CanadianPatentedMedicinePricesReviewBoard, us-gaap:SubsequentEvent


Escrow
Period End2021-04-282021-02-042020-10-27
Value807061
Percentage of EscrowDeposit100.0100.0100.0

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

us-gaap:FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue

us-gaap:FairValueInputsLevel3, alxn:AcquisitionRelatedContingentConsideration


Fair
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-312013-09-302012-12-31
Value-423.5-414.3-398.1-374.7-192.4-188.0-258.2-252.1-280.8-275.2-226.3168160157153207167162177158178174162142142144141
Percentage of FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinanceLeaseLiability

us-gaap:FinanceLeaseLiability


Finance
Period End2020-12-312019-12-31
Value7278
Percentage of FinanceLeaseLiability100.0100.0

us-gaap:FinanceLeaseLiabilityCurrent

us-gaap:FinanceLeaseLiabilityCurrent


Finance
Period End2020-12-312019-12-31
Value5600000.05200000.0
Percentage of FinanceLeaseLiabilityCurrent100.0100.0

us-gaap:FinanceLeaseLiabilityNoncurrent

us-gaap:FinanceLeaseLiabilityNoncurrent


Finance
Period End2020-12-312019-12-31
Value6772
Percentage of FinanceLeaseLiabilityNoncurrent100.0100.0

us-gaap:FinanceLeaseLiabilityPaymentsDue

us-gaap:FinanceLeaseLiabilityPaymentsDue


Finance
Period End2020-12-312019-12-31
Value91100
Percentage of FinanceLeaseLiabilityPaymentsDue100.0100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueAfterYearFive


Finance
Period End2020-12-31
Value45
Percentage of FinanceLeaseLiabilityPaymentsDueAfterYearFive100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths


Finance
Period End2020-12-31
Value9000000.0
Percentage of FinanceLeaseLiabilityPaymentsDueNextTwelveMonths100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive


Finance
Period End2020-12-31
Value9600000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearFive100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour


Finance
Period End2020-12-31
Value9400000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearFour100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree


Finance
Period End2020-12-31
Value9200000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearThree100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo


Finance
Period End2020-12-31
Value9200000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearTwo100.0

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount


Finance
Period End2020-12-312019-12-31
Value1822
Percentage of FinanceLeaseLiabilityUndiscountedExcessAmount100.0100.0

us-gaap:FinanceLeaseRightOfUseAsset

us-gaap:FinanceLeaseRightOfUseAsset


Finance
Period End2020-12-312019-12-312018-12-31
Value1051270.0
Percentage of FinanceLeaseRightOfUseAsset100.0100.00.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

alxn:PurchasedTechnology


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value373736843631357813881314123911591079999919758679519439358276196116360.00.00.7980.3820.0
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.00.0

us-gaap:LicensingAgreements


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value39383736343230292929282829292928282828282818139.6398.251
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization1.11.01.01.02.52.52.52.62.72.93.13.84.35.66.67.910.314.524.477.80.00.01648.12523.30.0

us-gaap:OtherIntangibleAssets


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-31
Value0.30.30.30.30.20.20.20.20.20.20.20.10.0
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Patents


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value1010101010101010101010101111111010101010109.16.8275.093.651
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization0.30.30.30.30.80.80.80.91.01.11.11.41.62.12.52.93.85.39.028.70.00.0855.51332.50.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths


Finite
Period End2020-12-31
Value216
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear


Finite
Period End2021-03-312020-09-30
Value16254
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear100.0100.0

us-gaap:FiniteLivedIntangibleAssetsGross us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:FiniteLivedIntangibleAssetsGross

alxn:PurchasedTechnology


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value574657465746471047104710471047104710471047104710471147114711471047084708470847080.00.05.05.00.0
Percentage of FiniteLivedIntangibleAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.00.0

us-gaap:LicensingAgreements


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value57575757574747393931313129292928282828282828232325
Percentage of FiniteLivedIntangibleAssetsGross1.01.01.01.21.21.01.00.80.80.70.70.70.60.60.60.60.60.60.60.60.00.0473.8473.00.0

us-gaap:Patents


Finite
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value10101010101010101010101011111110101010101010101010
Percentage of FiniteLivedIntangibleAssetsGross0.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.00.0210.3210.30.0

us-gaap:ForeignCurrencyContractAssetFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass

us-gaap:ForeignCurrencyContractAssetFairValueDisclosure

us-gaap:OtherNoncurrentAssets, us-gaap:ForeignExchangeForward


Foreign
Period End2021-03-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value0.10.40.64.11.11.70.30.71.94.17.04359314435666982125586.3629.839
Percentage of ForeignCurrencyContractAssetFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PrepaidExpensesAndOtherCurrentAssets, us-gaap:ForeignExchangeForward


Foreign
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302016-12-312016-09-302015-12-31
Value41261143294228314027162221975091
Percentage of ForeignCurrencyContractAssetFairValueDisclosure41500.00.02925.00.04983.31043.92590.91852.913500.03857.1863.2558.5300.0164.4161.7138.4

us-gaap:ForeignCurrencyContractAssetFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:OtherNoncurrentAssets, us-gaap:ForeignExchangeForward, us-gaap:FairValueInputsLevel2


Foreign
Period End2021-03-312020-09-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value0.10.40.64.11.11.70.30.71.94.17.04359314435666982125586.3629.839
Percentage of ForeignCurrencyContractAssetFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PrepaidExpensesAndOtherCurrentAssets, us-gaap:ForeignExchangeForward, us-gaap:FairValueInputsLevel2


Foreign
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302016-12-312016-09-302015-12-31
Value41261143294228314027162221975091
Percentage of ForeignCurrencyContractAssetFairValueDisclosure41500.00.02925.00.04983.31043.92590.91852.913500.03857.1863.2558.5300.0164.4161.7138.4

us-gaap:ForeignCurrencyContractsLiabilityFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByLiabilityClass

us-gaap:ForeignCurrencyContractsLiabilityFairValueDisclosure

us-gaap:OtherCurrentLiabilities, us-gaap:FairValueInputsLevel2, us-gaap:ForeignExchangeForward


Foreign
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value218024242617237.7181316483714123430325.6483.6922.9340.3360.7942120
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherLiabilities, us-gaap:FairValueInputsLevel2, us-gaap:ForeignExchangeForward


Foreign
Period End2020-12-312019-12-31
Value1.21.1
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure1.54.1

us-gaap:OtherNoncurrentLiabilities, us-gaap:FairValueInputsLevel2, us-gaap:ForeignExchangeForward


Foreign
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value1.20.30.41.10.81.80.93.15.89.926289.04.03836304.7735.8065.4860.0660.0861314
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure1.51.21.74.14.77.811.716.541.760.053.675.764.333.3109.9120.895.984.5157.3187.019.610.861.573.5

us-gaap:ForeignCurrencyContractsLiabilityFairValueDisclosure us-gaap:BalanceSheetLocation, us-gaap:FairValueByLiabilityClass

us-gaap:OtherCurrentLiabilities, us-gaap:ForeignExchangeForward


Foreign
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value218024242617237.7181316483714123430325.6483.6922.9340.3360.7942120
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherLiabilities, us-gaap:ForeignExchangeForward


Foreign
Period End2020-12-312019-12-31
Value1.21.1
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure1.54.1

us-gaap:OtherNoncurrentLiabilities, us-gaap:ForeignExchangeForward


Foreign
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-03-312013-12-31
Value1.20.30.41.10.81.80.93.15.89.926289.04.03836304.7735.8065.4860.0660.0861314
Percentage of ForeignCurrencyContractsLiabilityFairValueDisclosure1.51.21.74.14.77.811.716.541.760.053.675.764.333.3109.9120.895.984.5157.3187.019.610.861.573.5

us-gaap:GoodwillGross

us-gaap:GoodwillGross


Goodwill
Period End2021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312017-09-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-31
Value510351035103507850405040504050405040504050405040504050405040504050405052505050182562562568222
Percentage of GoodwillGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntangibleAssetsGrossExcludingGoodwill

us-gaap:IntangibleAssetsGrossExcludingGoodwill


Intangible
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value673647784760475247824865
Percentage of IntangibleAssetsGrossExcludingGoodwill100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateDerivativeAssetsAtFairValue us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass

us-gaap:InterestRateDerivativeAssetsAtFairValue

us-gaap:OtherLiabilities, us-gaap:InterestRateContract


Interest
Period End2020-09-302020-06-302019-12-312019-09-302019-06-302019-03-312018-12-31
Value57694155523117
Percentage of InterestRateDerivativeAssetsAtFairValue100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateDerivativeAssetsAtFairValue us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:OtherLiabilities, us-gaap:InterestRateContract, us-gaap:FairValueInputsLevel2


Interest
Period End2020-09-302020-06-302019-12-312018-12-31
Value5769410.8
Percentage of InterestRateDerivativeAssetsAtFairValue100.0100.0100.04.6

us-gaap:InterestRateDerivativeLiabilitiesAtFairValue us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass

us-gaap:InterestRateDerivativeLiabilitiesAtFairValue

us-gaap:OtherCurrentLiabilities, us-gaap:InterestRateContract


Interest
Period End2021-03-312020-12-312020-09-302020-06-302019-12-31
Value4545454519
Percentage of InterestRateDerivativeLiabilitiesAtFairValue100.0100.0100.0100.0100.0

us-gaap:OtherLiabilities, us-gaap:InterestRateContract


Interest
Period End2021-03-312020-12-31
Value3245
Percentage of InterestRateDerivativeLiabilitiesAtFairValue72.098.9

us-gaap:InterestRateDerivativeLiabilitiesAtFairValue us-gaap:BalanceSheetLocation, us-gaap:FairValueByAssetClass, us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:OtherCurrentLiabilities, us-gaap:InterestRateContract, us-gaap:FairValueInputsLevel2


Interest
Period End2021-03-312020-12-312020-09-302020-06-302019-12-31
Value4545454519
Percentage of InterestRateDerivativeLiabilitiesAtFairValue100.0100.0100.0100.0100.0

us-gaap:OtherLiabilities, us-gaap:InterestRateContract, us-gaap:FairValueInputsLevel2