Acquisitions (Details Textual) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Acquired in-process research and development	$ 75.0		$ 120.0	$ 85.0	$ 120.0
Karyopharm
Business Acquisition [Line Items]
Acquired in-process research and development		$ 10.0
Estimated additional payments upon achievement of milestones				207.0
Pfizer
Business Acquisition [Line Items]
Acquired in-process research and development	75.0
Estimated additional payments upon achievement of milestones				515.0
TMS
Business Acquisition [Line Items]
Acquired in-process research and development				18.0
Estimated additional payments upon achievement of milestones				335.0
Research and development expense asset acquired	$ 4.0
Development Milestones | Pfizer
Business Acquisition [Line Items]
Estimated additional payments upon achievement of milestones				$ 10.0