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Acquisitions (Details Textual) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Feb. 28, 2015 | Dec. 31, 2016 | Dec. 31, 2016 | Dec. 31, 2015 | Feb. 12, 2015
Business Acquisition [Line Items] |  |  |  |  |
Potential future milestone payments |  | $ 3,100.0 | $ 3,100.0 |  |
Contingent consideration obligation |  |  | 0.0 | $ 274.5 |
Maximum contingent consideration in the form of development and approval milestones |  | 1,200.0 | $ 1,200.0 |  |
Convergence Pharmaceuticals |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Cash portion of consideration | $ 200.1 |  |  |  |
Potential future milestone payments |  |  |  |  | $ 450.0
Contingent consideration obligation | 274.5 |  |  |  |
Increase in contingent consideration liability | $ 36.0 |  |  |  |
Discount rate | 2.00% |  | 2.70% |  |
Maximum contingent consideration in the form of development and approval milestones |  | 400.0 | $ 400.0 |  |
In-process research and development |  |  |  |  | 424.6
Milestone payment made during period |  | $ 50.0 |  |  |
BIIB074 | Convergence Pharmaceuticals |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Potential future milestone payments |  |  |  |  | 350.0
Discount rate | 11.00% |  |  |  |
Maximum contingent consideration in the form of development and approval milestones |  |  |  |  | 145.0
In-process research and development |  |  |  |  | 200.0
Neuropathic pain indications | Convergence Pharmaceuticals |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Maximum contingent consideration in the form of development and approval milestones |  |  |  |  | 415.0
In-process research and development |  |  |  |  | $ 220.0

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