XML 126 R71.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Fair Value Measurements (Details Textual) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Feb. 28, 2015 | Dec. 31, 2016 | Mar. 31, 2012 | Dec. 31, 2010 | Dec. 31, 2016 | Dec. 31, 2015 | Feb. 12, 2015 | Mar. 04, 2008
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Fair value measurements, changes in valuation techniques |  |  |  |  | 0 | 0 |  |
Additions |  |  |  |  | $ 0.0 | $ 274.5 |  |
Potential future milestone payments |  | $ 3,100.0 |  |  | 3,100.0 |  |  |
Maximum contingent consideration in the form of development and approval milestones |  | 1,200.0 |  |  | 1,200.0 |  |  |
Convergence Pharmaceuticals |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Milestone converted to short-term obligation |  | 7.9 |  |  | 7.9 |  |  |
Additions | $ 274.5 |  |  |  |  |  |  |
Potential future milestone payments |  |  |  |  |  |  | $ 450.0 |
Contingent consideration obligations |  | 258.9 |  |  | 258.9 | 297.5 |  |
Maximum contingent consideration in the form of development and approval milestones |  | 400.0 |  |  | $ 400.0 |  |  |
Discount rate used for net cash outflow projections for fair value measurement | 2.00% |  |  |  | 2.70% |  |  |
Milestone payments made during period |  | 50.0 |  |  |  |  |  |
In-process research and development |  |  |  |  |  |  | $ 424.6 |
Stromedix, Inc. |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Additions |  |  | $ 122.2 |  |  |  |  |
Contingent consideration obligations |  | 133.2 |  |  | $ 133.2 | 131.5 |  |
Maximum contingent consideration in the form of development and approval milestones |  | 419.0 |  |  | $ 419.0 |  |  |
Discount rate used for net cash outflow projections for fair value measurement |  |  |  |  | 2.20% |  |  |
Biogen Idec International Neuroscience GmbH |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Additions |  |  |  | $ 81.2 |  |  |  |
Contingent consideration obligations |  | 75.5 |  |  | $ 75.5 | $ 77.0 |  |
Maximum contingent consideration in the form of development and approval milestones |  | $ 361.7 |  |  | $ 361.7 |  |  |
Discount rate used for net cash outflow projections for fair value measurement |  |  |  |  | 2.70% |  |  |
Milestone payments made during period |  |  |  |  | $ 3.3 |  |  |
6.875% Senior Notes due 2018 |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Interest rate on senior notes |  | 6.875% |  |  | 6.875% |  |  | 6.875%
2.90% Senior Notes due 2020 |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Interest rate on senior notes |  | 2.90% |  |  | 2.90% | 2.90% |  |
3.625% Senior Notes due 2022 |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Interest rate on senior notes |  | 3.625% |  |  | 3.625% | 3.625% |  |
4.05% Senior Notes due 2025 |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Interest rate on senior notes |  | 4.05% |  |  | 4.05% | 4.05% |  |
5.20% Senior Notes due 2045 |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Interest rate on senior notes |  | 5.20% |  |  | 5.20% | 5.20% |  |
Other long-term liabilities |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Contingent consideration obligations |  | $ 246.8 |  |  | $ 246.8 | $ 301.3 |  |
Accrued expenses and other | Convergence Pharmaceuticals |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Contingent consideration obligations |  | 148.4 |  |  | 148.4 |  |  |
Accrued expenses and other | Stromedix, Inc. |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Contingent consideration obligations |  | 56.9 |  |  | 56.9 |  |  |
Accrued expenses and other | Biogen Idec International Neuroscience GmbH |  |  |  |  |  |  |  |
Business Acquisition, Contingent Consideration [Line Items] |  |  |  |  |  |  |  |
Contingent consideration obligations |  | $ 15.5 |  |  | $ 15.5 |  |  |

X
- Definition Milestone Payments Made During Period. + References No definition available. + Details
Name: | biib_MilestonePaymentsMadeDuringPeriod
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Potential future milestone payments commitment to third party approximately. + References No definition available. + Details
Name: | biib_PotentialFutureMilestonePaymentsCommitmentToThirdPartyApproximately
Namespace Prefix: | biib_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_BusinessAcquisitionContingentConsiderationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
Name: | us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of liability recognized arising from contingent consideration in a business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 35 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476 + Details
Name: | us-gaap_BusinessCombinationContingentConsiderationLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 35 -Paragraph 1 -Subparagraph b -URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478 + Details
Name: | us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Description of the changes in valuation technique(s) and related inputs used to measure fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementsChangesInValuationTechniques
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of liabilities classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.15) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_OtherLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=biib_ConvergencePharmaceuticalsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=biib_StromedixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=biib_BiogenIdecInternationalNeuroscienceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=biib_SeniorNotesSixPointEightSevenFivePercentDueTwentyEighteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=biib_SeniorNotesTwoPointNinePercentDueTwentyTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=biib_SeniorNotesThreePointSixTwoFivePercentDueTwentyTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=biib_SeniorNotesFourPointZeroFivePercentDueTwentyTwentyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=biib_SeniorNotesFivePointTwoPercentDueTwentyFortyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContingentConsiderationByTypeAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ContingentConsiderationByTypeAxis=us-gaap_AccruedLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |