XML 80 R45.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Reserves for Discounts and Allowances (Details 1) - USD ($) $ in Millions | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Summary of total product revenue reserves included in consolidated balance sheets |  |
Total reserves | $ 724.3 | $ 605.5
Reduction of accounts receivable |  |
Summary of total product revenue reserves included in consolidated balance sheets |  |
Total reserves | 191.0 | 166.9
Component of accrued expenses and other |  |
Summary of total product revenue reserves included in consolidated balance sheets |  |
Total reserves | $ 533.3 | $ 438.6

X
- Definition Summary of product revenue reserves included in consolidated balance sheets. + References No definition available. + Details
Name: | biib_SummaryOfProductRevenueReservesIncludedInConsolidatedBalanceSheetsAbstract
Namespace Prefix: | biib_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
Name: | us-gaap_ValuationAllowancesAndReservesBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_AccountsReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherCurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |