XML 82 R48.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Inventory Inventory (Details Textual) $ in Millions | Dec. 31, 2015 USD ($)
--- | ---
ZINBRYTA |
Inventory [Line Items] |
Pre-approval inventory | $ 24.7
FLIXABI |
Inventory [Line Items] |
Pre-approval inventory | 24.2
BENEPALI |
Inventory [Line Items] |
Pre-approval inventory | $ 18.4

X
- Definition Pre-approval inventory + References No definition available. + Details
Name: | biib_Preapprovalinventory
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_ProductOrServiceAxis=biib_ZINBRYTAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ProductOrServiceAxis=biib_FLIXABIMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ProductOrServiceAxis=biib_BENEPALIMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |