Investments in Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Net (loss) income attributable to noncontrolling interests, net of tax				$ (7.1)	$ 46.2	$ 6.8
Investment in Variable Interest Entities (Textual)
Investment in biotechnology companies that are determined to be unconsolidated variable interest entities	$ 29.2			47.4	29.2
Neurimmune
Variable Interest Entity [Line Items]
Net (loss) income attributable to noncontrolling interests, net of tax		$ 60.0
Investment in Variable Interest Entities (Textual)
Remaining potential development milestone payments and royalties on commercial sales under the terms of collaboration agreement				$ 275.0
Percentage of funding for R&D cost required in support of the collaboration agreement				100.00%
Rodin Therapeutics
Investment in Variable Interest Entities (Textual)
Payments to acquire interest in peferred stock of an affiliates	8.0
In-process research and development	8.7
Minority interest in our stockholder's equity	$ 10.9				$ 10.9
Ataxion
Investment in Variable Interest Entities (Textual)
Payments to acquire interest in peferred stock of an affiliates			$ 1.6
In-process research and development			$ 3.5