XML 77 R45.htm IDEA: XBRL DOCUMENT
v3.22.1

Revenues Reserves for Discounts and Allowances (Details 1) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2022 USD ($)
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |
Beginning Balance | $ 935.3
Current Provisions Relating To Sales In Current Year | 832.5
Adjustments Relating To Prior Years | (46.6)
Payments/Returns Relating To Sales in Current Year | (373.3)
Payments/Returns Relating To Sales in Prior Year | (379.9)
Ending Balance | 968.0
Discounts |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |
Beginning Balance | 137.7
Current Provisions Relating To Sales In Current Year | 169.0
Adjustments Relating To Prior Years | (3.9)
Payments/Returns Relating To Sales in Current Year | (101.2)
Payments/Returns Relating To Sales in Prior Year | (58.9)
Ending Balance | 142.7
Contractual adjustments |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |
Beginning Balance | 759.6
Current Provisions Relating To Sales In Current Year | 659.5
Adjustments Relating To Prior Years | (40.2)
Payments/Returns Relating To Sales in Current Year | (271.6)
Payments/Returns Relating To Sales in Prior Year | (314.5)
Ending Balance | 792.8
Returns |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |
Beginning Balance | 38.0
Current Provisions Relating To Sales In Current Year | 4.0
Adjustments Relating To Prior Years | (2.5)
Payments/Returns Relating To Sales in Current Year | (0.5)
Payments/Returns Relating To Sales in Prior Year | (6.5)
Ending Balance | $ 32.5

X
- Definition Adjustments to product revenue reserves relating to sales in prior years. + References No definition available. + Details
Name: | biib_AdjustmentsToProductRevenueReservesRelatingToSalesInPriorYears
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Current provisions to product revenue reserves relating to sales in current year. + References No definition available. + Details
Name: | biib_CurrentProvisionsToProductRevenueReservesRelatingToSalesInCurrentYear
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Payments/ returns applied against product revenue reserves relating to current year. + References No definition available. + Details
Name: | biib_PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Payments/ returns applied against product revenue reserves relating to prior year. + References No definition available. + Details
Name: | biib_PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | srt_ValuationAndQualifyingAccountsDisclosureLineItems
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column B)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column E)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 + Details
Name: | us-gaap_ValuationAllowancesAndReservesBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_ValuationAllowancesAndReservesTypeAxis=biib_ReserveforCashDiscountsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationAllowancesAndReservesTypeAxis=biib_ContractualAdjustmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationAllowancesAndReservesTypeAxis=us-gaap_SalesReturnsAndAllowancesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |