Investments in Variable Interest Entities (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	May 31, 2018	Oct. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Payment to Neurimmune			$ (4.3)	$ 36.4	$ 134.1
Potential Future Milestone Payments Commitment To Third Party Approximately			6,800.0
Investment in Variable Interest Entities (Textual)
Investment in biotechnology companies that are determined to be unconsolidated variable interest entities			22.7	$ 28.7
Neurimmune
Variable Interest Entity [Line Items]
Payment to Neurimmune	$ 50.0	$ 150.0
Additional reduction in royalty rate payable on commercial sales	5.00%
Reduction in royalty rate payable on commercial sales		15.00%
Regulatory Milestones
Variable Interest Entity [Line Items]
Potential Future Milestone Payments Commitment To Third Party Approximately			1,400.0
Regulatory Milestones | Neurimmune
Variable Interest Entity [Line Items]
Potential Future Milestone Payments Commitment To Third Party Approximately			75.0
Regulatory Approval Milestone | Neurimmune
Variable Interest Entity [Line Items]
Potential Future Milestone Payments Commitment To Third Party Approximately			$ 100.0