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Acquisitions Acquisitions (Details) - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Feb. 28, 2015 | Dec. 31, 2016 | Dec. 31, 2015
Business Acquisition [Line Items] |  |  |
Contingent consideration obligation |  | $ 0.0 | $ 274.5
Convergence Pharmaceuticals |  |  |
Business Acquisition [Line Items] |  |  |
Cash portion of consideration | $ 200.1 |  |
Contingent consideration obligation | 274.5 |  |
Total purchase price | $ 474.6 |  |

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