Collaborative Arrangements and Pending Acquisition - Merck KGaA (Details)		3 Months Ended
	Jan. 10, 2017 USD ($) pre-clinical_stage_program clinical-stage_program development_program	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenues		$ 232,545,000	$ 74,000
Collaborative revenues, related to upfront payment upon delivery of license and to research and development transition activities		231,700,000
Merck KGaA
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Right to license, number of development programs | development_program	4
Right to license, number of clinical stage programs | clinical-stage_program	2
Number of pre-clinical stage programs | pre-clinical_stage_program	2
Up-front payment	$ 230,000,000.0
Collaborative revenues		193,600,000
Time period of notice required to terminate	90 days
Time period of notice required to terminate after a product has received marketing approval	180 days
German Tax Authority | Merck KGaA
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative revenues, tax withholding		$ 36,400,000