beatandraise : Equity Research with AI and ChatGPT on SEC Edgar

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2.2.0.7 true Share-Based Payments (Details) (USD $) 0613 - Disclosure - Share-Based Payments (Details) true false false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 3 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 4 USD false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ 2 Share-based Compensation Expense included in consolidated statements of income 2 us-gaap_ShareBasedCompensationAllocationAndClassificationInFinancialStatementsAbstract us-gaap true na duration No definition available. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 3 Share-based compensation expense included in total costs and expenses 2 us-gaap_AllocatedShareBasedCompensationExpense us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 true true false false 41900000 41900000 false false false 2 true true false false 41100000 41100000 false false false 3 true true false false 142600000 142600000 false false false 4 true true false false 119900000 119900000 false false false xbrli:monetaryItemType monetary Represents the expense recognized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph g(1) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F false 4 Capitalized share-based payment costs 2 us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -900000 -900000 false false false 2 false true false false -1700000 -1700000 false false false 3 false true false false -2500000 -2500000 false false false 4 false true false false -4800000 -4800000 false false false xbrli:monetaryItemType monetary Represents the compensation cost capitalized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph g(1) false 5 Income tax effect 2 biib_IncomeTaxEffect biib false debit duration The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to share-based... false false false false false false false false false false false verboselabel false 1 false true false false -13000000 -13000000 false false false 2 false true false false -12600000 -12600000 false false false 3 false true false false -45400000 -45400000 false false false 4 false true false false -36800000 -36800000 false false false xbrli:monetaryItemType monetary The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to share-based compensation. No authoritative reference available. false 6 Summary of share based compensation expense associated with different programs 2 biib_SummaryOfShareBasedCompensationExpenseAssociatedWithDifferentProgramsAbstract biib false na duration Summary of share-based compensation expense associated with different programs. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string Summary of share-based compensation expense associated with different programs. false 7 Stock options 2 biib_StockOptionPlanExpenses biib false debit duration The noncash expense that accounts for the value of stock options distributed to employees and directors as compensation. false false false false false false false false false false false verboselabel false 1 false true false false 3000000 3000000 false false false 2 false true false false 5500000 5500000 false false false 3 false true false false 23100000 23100000 false false false 4 false true false false 16600000 16600000 false false false xbrli:monetaryItemType monetary The noncash expense that accounts for the value of stock options distributed to employees and directors as compensation. No authoritative reference available. false 8 Market stock units 2 biib_MarketStockUnits biib false na duration Aggregate awards of shares and nonvested shares to be issued to an employee under a time-based compensation arrangement are... false false false false false false false false false false false verboselabel false 1 false true false false 2300000 2300000 false false false 2 false false false false 0 0 false false false 3 false true false false 7800000 7800000 false false false 4 false false false false 0 0 false false false xbrli:sharesItemType shares Aggregate awards of shares and nonvested shares to be issued to an employee under a time-based compensation arrangement are considered shares for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon time and market conditions vesting and employment status. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding. No authoritative reference available. false 9 Time-vested restricted stock units 2 biib_RestrictedStockExpenseTimeVestedRestrictedStockUnits biib false debit duration The noncash expense that represents the cost of restricted stock distributed to employees and directors as compensation. false false false false false false false false false false false verboselabel false 1 false true false false 30800000 30800000 false false false 2 false true false false 34400000 34400000 false false false 3 false true false false 96500000 96500000 false false false 4 false true false false 99900000 99900000 false false false xbrli:monetaryItemType monetary The noncash expense that represents the cost of restricted stock distributed to employees and directors as compensation. No authoritative reference available. false 10 Performance-vested restricted stock units settled in shares 2 biib_PerformanceVestedRestrictedStockUnitsSettledInShares biib false na duration Performance-vested restricted stock units settled in shares. false false false false false false false false false false false verboselabel false 1 false true false false 700000 700000 false false false 2 false true false false -300000 -300000 false false false 3 false true false false 4400000 4400000 false false false 4 false true false false 3000000 3000000 false false false xbrli:sharesItemType shares Performance-vested restricted stock units settled in shares. No authoritative reference available. false 11 Performance-vested restricted stock units settled in cash 2 biib_PerformanceVestedRestrictedStockUnitsSettledInCash biib false na duration Performance-vested restricted stock units settled in cash. false false false false false false false false false false false verboselabel false 1 false true false false 2700000 2700000 false false false 2 false false false false 0 0 false false false 3 false true false false 8000000 8000000 false false false 4 false false false false 0 0 false false false xbrli:monetaryItemType monetary Performance-vested restricted stock units settled in cash. No authoritative reference available. false 12 Employee stock purchase plan 2 biib_EmployeeStockPurchasePlan biib false debit duration The noncash expense that accounts for the value of employee stock purchase plan. false false false false false false false false false false false verboselabel false 1 false true false false 3300000 3300000 false false false 2 false true false false 3200000 3200000 false false false 3 false true false false 5300000 5300000 false false false 4 false true false false 5200000 5200000 false false false xbrli:monetaryItemType monetary The noncash expense that accounts for the value of employee stock purchase plan. No authoritative reference available. false 13 Capitalized share-based payment costs 2 us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -900000 -900000 false false false 2 false true false false -1700000 -1700000 false false false 3 false true false false -2500000 -2500000 false false false 4 false true false false -4800000 -4800000 false false false xbrli:monetaryItemType monetary Represents the compensation cost capitalized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph g(1) false 14 Share-based compensation expense included in total costs and expenses 2 us-gaap_AllocatedShareBasedCompensationExpense us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 41900000 41900000 false false false 2 false true false false 41100000 41100000 false false false 3 false true false false 142600000 142600000 false false false 4 false true false false 119900000 119900000 false false false xbrli:monetaryItemType monetary Represents the expense recognized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph g(1) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F false 17 Share Based Payments (Textuals) [Abstract] 2 biib_ShareBasedPaymentsTextualsAbstract biib false na duration Share-Based Payments. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string Share-Based Payments. false 21 Employee stock purchase plan 2 us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 457000 457000 false false false 4 false true false false 426000 426000 false false false xbrli:sharesItemType shares Number of shares issued during the period as a result of an employee stock purchase plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 10 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 5 false 22 Percentage of granted PVRSUs earned on the basis of 2009 performance 2 biib_PercentageOfGrantedPvrsusEarnedOnBasisOfPriorYearPerformance biib false na duration Percentage Of Granted Pvrsus Earned On Basis Of Prior Year Performance. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.99 0.99 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Percentage Of Granted Pvrsus Earned On Basis Of Prior Year Performance. No authoritative reference available. false 23 Expected dividend yield 2 biib_ExpectedDividendYield biib false na duration The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying... false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0 0 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the award's term. No authoritative reference available. false 24 Minimum range of risk-free rates of return 2 biib_MinimumRangeOfRiskFreeInterestRatesInPercentage biib false na duration Minimum Range Of Risk Free Interest Rates In Percentage. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.003 0.003 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Minimum Range Of Risk Free Interest Rates In Percentage. No authoritative reference available. false 25 Maximum range of risk-free rates of return 2 biib_MaximumRangeOfRiskFreeInterestRatesInPercentage biib false na duration Maximum Range Of Risk Free Interest Rates In Percentage. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.02 0.02 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Maximum Range Of Risk Free Interest Rates In Percentage. No authoritative reference available. false 26 60 calendar day average stock price on grant date, maximum 2 biib_AverageStockPriceOnGrantDateInDollarsMaximum biib false na duration Average Stock Price On Grant Date In Dollars Maximum. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 54.12 54.12 false false false 4 false false false false 0 0 false false false xbrli:monetaryItemType monetary Average Stock Price On Grant Date In Dollars Maximum. No authoritative reference available. false 27 60 calendar day average stock price on grant date, Minimum 2 biib_AverageStockPriceOnGrantDateInDollarsMinimum biib false na duration Average Stock Price On Grant Date In Dollars Minimum. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 49.08 49.08 false false false 4 false false false false 0 0 false false false xbrli:monetaryItemType monetary Average Stock Price On Grant Date In Dollars Minimum. No authoritative reference available. false 28 Number of new forms of equity-based compensation 2 biib_NumberOfNewFormsOfEquityBasedCompensation biib false na duration Number of new forms of equity-based compensation. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 2 2 false false false 4 false false false false 0 0 false false false xbrli:integerItemType integer Number of new forms of equity-based compensation. No authoritative reference available. false 29 Number of equal annual increments for Market Stock Units awards 2 biib_NumberOfEqualAnnualIncrementsForMarketStockUnitsAwards biib false na duration Number of equal annual increments for Market Stock Units awards. false false false false false false false false false false false label false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 4 4 false false false 4 false false false false 0 0 false false false xbrli:integerItemType integer Number of equal annual increments for Market Stock Units awards. No authoritative reference available. false 30 Calendar day average closing stock price on grant date for Market Stock Units 2 biib_CalendarDayAverageClosingStockPriceGrantDate biib false na duration Calendar day average closing stock price grant date. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 60 60 false false false 4 false false false false 0 0 false false false xbrli:integerItemType integer Calendar day average closing stock price grant date. No authoritative reference available. false 31 Restricted stock units received by executive 2 biib_RestrictedStockUnitsReceivedByExecutive biib false na duration Restricted stock units received by executive false false false false false false false false false false false label false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 63165 63165 false false false 4 false false false false 0 0 false false false xbrli:sharesItemType shares Restricted stock units received by executive No authoritative reference available. false 32 Market stock units received by executive 2 biib_MarketStockUnitsReceivedByExecutive biib false na duration Market stock units received by executive false false false false false false false false false false false label false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 56905 56905 false false false 4 false false false false 0 0 false false false xbrli:sharesItemType shares Market stock units received by executive No authoritative reference available. false 33 Number of equal annual increments for Cash Settled Performance Shares awards 2 biib_NumberOfEqualAnnualIncrementsForCashSettledPerformanceSharesAwards biib false na duration Number of equal annual increments for Cash Settled Performance Shares awards. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 3 3 false false false 4 false false false false 0 0 false false false xbrli:integerItemType integer Number of equal annual increments for Cash Settled Performance Shares awards. No authoritative reference available. false 34 Calendar day average closing stock price for Cash Settled Performance Shares based on vesting date 2 biib_CalendarDayAverageClosingStockPriceForCashSettledPerformanceSharesBasedOnVestingDate biib false na duration Calendar day average closing stock price for Cash Settled Performance Shares based on vesting date. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 60 60 false false false 4 false false false false 0 0 false false false xbrli:integerItemType integer Calendar day average closing stock price for Cash Settled Performance Shares based on vesting date. No authoritative reference available. false 35 Minimum target number of market stock units granted based on stock performance in percent 2 biib_MinimumTargetNumberOfMarketStockUnitsGrantedBasedOnStockPerformanceInPercent biib false na duration Minimum Target Number Of Market Stock Units Granted Based On Stock Performance In Percent. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0 0 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Minimum Target Number Of Market Stock Units Granted Based On Stock Performance In Percent. No authoritative reference available. false 36 Maximum target number of market stock units granted based on stock performance in percent 2 biib_MaximumTargetNumberOfMarketStockUnitsGrantedBasedOnStockPerformanceInPercent biib false na duration Maximum Target Number Of Market Stock Units Granted Based On Stock Performance In Percent. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 1.5 1.5 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Maximum Target Number Of Market Stock Units Granted Based On Stock Performance In Percent. No authoritative reference available. false 37 Minimum Earning of target number of units granted based on the degree of actual performance metric achievement 2 biib_MinimumEarningOfTargetNumberOfUnitsGrantedBasedOnDegreeOfActualPerformanceMetricAchievement biib false na duration Minimum Earning of target number of cash settled performance shares granted based on the degree of actual performance metric... false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0 0 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Minimum Earning of target number of cash settled performance shares granted based on the degree of actual performance metric achievement. No authoritative reference available. false 38 Maximum Earning of target number of units granted based on the degree of actual performance metric achievement 2 biib_MaximumEarningOfTargetNumberOfUnitsGrantedBasedOnDegreeOfActualPerformanceMetricAchievement biib false na duration Maximum Earning of target number of cash settled performance shares granted based on the degree of actual performance metric... false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 2 2 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Maximum Earning of target number of cash settled performance shares granted based on the degree of actual performance metric achievement. No authoritative reference available. false 39 Purchase price of common stock under the employee stock purchase plan 2 biib_PurchasePriceOfCommonStockUnderEmployeeStockPurchasePlan biib false na duration Purchase price of common stock under the employee stock purchase plan. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.85 0.85 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Purchase price of common stock under the employee stock purchase plan. No authoritative reference available. false 40 Discount of the purchase price of common stock under the employee stock purchase plan 2 biib_DiscountOfPurchasePriceOfCommonStockUnderEmployeeStockPurchasePlan biib false na duration Discount of the purchase price of common stock under the employee stock purchase plan. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.15 0.15 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Discount of the purchase price of common stock under the employee stock purchase plan. No authoritative reference available. false 41 Percentage of granted PVRSUs earned on the basis of 2009 performance 2 biib_PercentageOfGrantedPvrsusEarnedOnBasisOfPriorYearPerformance biib false na duration Percentage Of Granted Pvrsus Earned On Basis Of Prior Year Performance. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.99 0.99 false false false 4 false false false false 0 0 false false false us-types:percentItemType pure Percentage Of Granted Pvrsus Earned On Basis Of Prior Year Performance. No authoritative reference available. false 42 Stock Options [Member] 0 na true na na No definition available. false true false false false false false false false false false http://biogenidec.com/role/sharebasedpaymentsdetails false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false false 5 USD true false false false Stock Options [Member] us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_StockOptionsMember us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 6 USD true false false false Stock Options [Member] us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_StockOptionsMember us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ na No definition available. No authoritative reference available. false 58 Share Based Payments (Textuals) [Abstract] 2 biib_ShareBasedPaymentsTextualsAbstract biib false na duration Share-Based Payments. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string Share-Based Payments. false 59 Number Granted 2 biib_NumberGranted biib false na duration The quantity of shares issuable on stock awards awarded under the plan during the reporting period. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 124000 124000 false false false 4 false true false false 1000000 1000000 false false false xbrli:sharesItemType shares The quantity of shares issuable on stock awards awarded under the plan during the reporting period. No authoritative reference available. false 60 Weighted Average Grant Date Fair Value 2 biib_WeightedAverageGrantDateFairValue biib false na duration The weighted average grant-date fair value of awards granted during the reporting period. false false false false false false false false false false false verboselabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 16.52 16.52 false false false 4 true true false false 18.01 18.01 false false false us-types:perShareItemType decimal The weighted average grant-date fair value of awards granted during the reporting period. No authoritative reference available. false 61 Weighted Average Exercise Price 2 biib_ShareBasedCompensationArrangementByStockOptionsGrantsInPeriodWeightedAverageExercisePrice biib false na duration Share Based Compensation Arrangement By Stock Options Grants In Period Weighted Average Exercise Price. false false false false false false false false false false false verboselabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 57.38 57.38 false false false 4 true true false false 50.02 50.02 false false false us-types:perShareItemType decimal Share Based Compensation Arrangement By Stock Options Grants In Period Weighted Average Exercise Price. No authoritative reference available. false 83 Time vested Restricted stock units [Member] 0 na true na na No definition available. false true false false false false false false false false false http://biogenidec.com/role/sharebasedpaymentsdetails false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false false 7 USD true false false false Time vested Restricted stock units [Member] us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis xbrldi http://xbrl.org/2006/xbrldi biib_TimeVestedRestrictedStockUnitsMember us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 8 USD true false false false Time vested Restricted stock units [Member] us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis xbrldi http://xbrl.org/2006/xbrldi biib_TimeVestedRestrictedStockUnitsMember us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ na No definition available. No authoritative reference available. false 99 Share Based Payments (Textuals) [Abstract] 2 biib_ShareBasedPaymentsTextualsAbstract biib false na duration Share-Based Payments. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string Share-Based Payments. false 100 Number Granted 2 biib_NumberGranted biib false na duration The quantity of shares issuable on stock awards awarded under the plan during the reporting period. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 2000000 2000000 false false false 4 false true false false 2500000 2500000 false false false xbrli:sharesItemType shares The quantity of shares issuable on stock awards awarded under the plan during the reporting period. 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