Collaborative Arrangements and Acquisitions - Aggregate VIE Financial Information, Summary of Net Income Attributable to noncontrolling (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Variable Interest Entity, Primary Beneficiary, Does Not Hold Majority Voting Interest, Disclosures [Abstract]
Provision for income taxes	$ (12,659)	$ 3,985
Net income attributable to noncontrolling interest	(17,038)	(1,792)
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity, Primary Beneficiary, Does Not Hold Majority Voting Interest, Disclosures [Abstract]
Loss attributable to noncontrolling interest before provision for income taxes and changes in fair value of contingent payments	557	1,547
Provision for income taxes	6,405	391
Increase in fair value of contingent payments	(24,000)	(3,730)
Net income attributable to noncontrolling interest	$ (17,038)	$ (1,792)