XML 32 R127.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Segment Information (Details Textual) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 segment | Dec. 31, 2012 | Dec. 31, 2011
Revenue from External Customer [Line Items] |  |  |
Revenues from unconsolidated joint business in percentage | 16.00% | 21.00% | 20.00%
Long-lived assets related to operations in Denmark | $ 1,750.7 | $ 1,742.2 | $ 1,838.4
Segment Information (Textual) [Abstract] |  |  |
Number of reportable segment | 1 |  |
Distributor One |  |  |
Revenue from External Customer [Line Items] |  |  |
Entity wide percentage of revenue from major distributors | 32.00% | 20.00% | 18.00%
Distributor Two |  |  |
Revenue from External Customer [Line Items] |  |  |
Entity wide percentage of revenue from major distributors | 24.00% | 10.00% | 10.00%
DENMARK |  |  |
Revenue from External Customer [Line Items] |  |  |
Long-lived assets related to operations in Denmark | $ 731.1 | $ 713.4 | $ 668.5

X
- Definition Entity wide percentage of revenue from major distributors. + References No definition available. + Details
Name: | biib_EntityWidePercentageOfRevenueFromMajorDistributors
Namespace Prefix: | biib_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Revenues in percentage from unconsolidated joint business. + References No definition available. + Details
Name: | biib_RevenuesInPercentageFromUnconsolidatedJointBusiness
Namespace Prefix: | biib_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | biib_SegmentInformationTextualAbstract
Namespace Prefix: | biib_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 41 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599 + Details
Name: | us-gaap_NoncurrentAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References No definition available. + Details
Name: | us-gaap_NumberOfReportableSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration