XML 51 R87.htm IDEA: XBRL DOCUMENT
v3.3.0.814

Subsequent Events Subsequent Events (Details) - Subsequent Event $ in Millions | Oct. 21, 2015 USD ($)
--- | ---
Subsequent Event [Line Items] |
Workforce reduction percentage | 11.00%
Minimum |
Subsequent Event [Line Items] |
Expected restructuring charges | $ 85
Expected cash payments | 115
Maximum |
Subsequent Event [Line Items] |
Expected restructuring charges | 95
Expected cash payments | $ 120

X
- Definition Restructuring and Related Cost, Expected Cash Payments + References No definition available. + Details
Name: | biib_RestructuringandRelatedCostExpectedCashPayments
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Workforce reduction percentage + References No definition available. + Details
Name: | biib_Workforcereductionpercentage
Namespace Prefix: | biib_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount expected to be recognized in earnings for the specified restructuring cost. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 5.P.4(b)) -URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section P -Subsection 3, 4 + Details
Name: | us-gaap_RestructuringAndRelatedCostExpectedCost1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |