XML 36 R48.htm IDEA: XBRL DOCUMENT
v3.2.0.727

Inventory Inventory (Details Textual) - USD ($) $ in Millions | Jun. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Inventory Disclosure [Abstract] |  |
Inventory, Various Programs, Gross | $ 35.8 | $ 6.3

X
- Definition Gross inventory of various programs which have been capitalized in advance of regulatory approval. + References No definition available. + Details
Name: | biib_InventoryVariousProgramsGross
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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