XML 180 R122.htm IDEA: XBRL DOCUMENT v3.3.1.900

Segment Information (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Revenue from External Customer [Line Items]
Revenues from unconsolidated joint business in percentage	12.00%	12.00%	16.00%
Long-lived assets related to operations in Denmark	$ 2,187.6	$ 1,765.7	$ 1,750.7
Segment Information (Textual) [Abstract]
Number of reportable segment | segment	1
Distributor One
Revenue from External Customer [Line Items]
Entity wide percentage of revenue from major distributors	34.00%	33.00%	32.00%
Distributor Two
Revenue from External Customer [Line Items]
Entity wide percentage of revenue from major distributors	26.00%	27.00%	24.00%
DENMARK
Revenue from External Customer [Line Items]
Long-lived assets related to operations in Denmark	$ 684.9	$ 676.0	$ 731.1

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

- Definition

Segment Information.

+ References

No definition available.

+ Details

Name:	biib_SegmentInformationTextualAbstract
Namespace Prefix:	biib_
Data Type:	xbrli:stringItemType
Balance Type:	na
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

No definition available.

+ 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=51669610&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

X

- Details

Name:	biib_MajorDistributorAxis=biib_DistributorOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	biib_MajorDistributorAxis=biib_DistributorTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementGeographicalAxis=country_DK
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: