XML 48 R30.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Reserves for Discounts and Allowances (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2014
Reserves for Discounts and Allowances [Abstract] |
Analysis of the amount of, and change in, reserves | An analysis of the change in reserves for discounts and allowances is summarized as follows:
(In millions) | Discounts |  | Contractual Adjustments |  | Returns |  | Total
Balance, as of December 31, 2013 | $ | 47.0 |  |  | $ | 335.6 |  |  | $ | 33.7 |  |  | $ | 416.3 |
Current provisions relating to sales in current year | 78.2 |  |  | 293.2 |  |  | 7.1 |  |  | 378.5 |
Adjustments relating to prior years | (1.4 | ) |  | (2.1 | ) |  | 4.4 |  |  | 0.9 |
Payments/returns relating to sales in current year | (30.7 | ) |  | (91.4 | ) |  | (0.1 | ) |  | (122.2 | )
Payments/returns relating to sales in prior years | (41.2 | ) |  | (159.0 | ) |  | (8.3 | ) |  | (208.5 | )
Balance, as of March 31, 2014 | $ | 51.9 |  |  | $ | 376.3 |  |  | $ | 36.8 |  |  | $ | 465.0 |
Total reserves, included in consolidated balance sheets | The total reserves above, included in our condensed consolidated balance sheets, are summarized as follows:
(In millions) | As of March 31, 2014 |  | As of December 31, 2013
Reduction of accounts receivable | $ | 134.5 |  |  | $ | 151.4 |
Component of accrued expenses and other | 330.5 |  |  | 264.9 |
Total reserves | $ | 465.0 |  |  | $ | 416.3 |

X
- Definition Analysis of amount of and change in product revenue reserves. + References No definition available. + Details
Name: | biib_AnalysisOfAmountOfAndChangeInProductRevenueReservesTableTextBlock
Namespace Prefix: | biib_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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

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