XML 122 R103.htm IDEA: XBRL DOCUMENT
v3.25.1

Collaborative and Other Relationships - Other Research and Discovery Arrangements and Funding Arrangements (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2025 | Feb. 11, 2025
Collaborative arrangements and non-collaborative arrangement transactions |  |
Reduction of research and development expense | $ 50.0 |
Milestone Payment, Future Development |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |
Estimated additional payments upon achievement of development and commercial milestones | 250.0 |
Felzartamab And Izastobart/HIB210 | Human Immunology Biosciences Pre-Existing In License Commitments | Milestone Payment, One |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |
Estimated additional payments upon achievement of development and commercial milestones | 35.0 |
Felzartamab And Izastobart/HIB210 | Human Immunology Biosciences Pre-Existing In License Commitments | Milestone Payment, Two |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |
Estimated additional payments upon achievement of development and commercial milestones | 30.0 |
Felzartamab And Izastobart/HIB210 | Human Immunology Biosciences Pre-Existing In License Commitments | Milestone Payment, Future Development |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |
Estimated additional payments upon achievement of development and commercial milestones | 130.0 |
Felzartamab And Izastobart/HIB210 | Human Immunology Biosciences Pre-Existing In License Commitments | Milestone Payment, Commercial |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |
Estimated additional payments upon achievement of development and commercial milestones | $ 640.0 |
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |
Expected receipts to co-fund development costs, current |  | $ 200.0
Expected receipts to co-fund development costs, noncurrent |  | $ 50.0

X
- Definition Collaborative Arrangement, Expected Development Cost Funds, Year One + References No definition available. + Details
Name: | biib_CollaborativeArrangementExpectedDevelopmentCostFundsYearOne
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Collaborative Arrangement, Expected Development Cost Funds, Year Two + References No definition available. + Details
Name: | biib_CollaborativeArrangementExpectedDevelopmentCostFundsYearTwo
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Estimated additional payments upon achievement of development and commercial milestones. + References No definition available. + Details
Name: | biib_EstimatedAdditionalPaymentsUponAchievementOfDevelopmentAndCommercialMilestones
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reduction Of Research And Development Expense + References No definition available. + Details
Name: | biib_ReductionOfResearchAndDevelopmentExpense
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 808 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479402/808-10-50-1 + Details
Name: | us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ContingentConsiderationByTypeAxis=biib_MilestonePaymentFutureDevelopmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=biib_FelzartamabAndIzastobartHIB210Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAxis=biib_HumanImmunologyBiosciencesPreExistingInLicenseCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContingentConsiderationByTypeAxis=biib_MilestonePaymentOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContingentConsiderationByTypeAxis=biib_MilestonePaymentTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContingentConsiderationByTypeAxis=biib_MilestonePaymentCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TypeOfArrangementAxis=us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |