License, Collaboration and Other Significant Agreements - Schedule of Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities, Balance at End of Period		$ 106,471
Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract assets, Balance at Beginning of Period	[1]	1,587	$ 34,186
Contract assets, Additions	[1]	30,387	36,061
Contract assets, Deductions	[1]	(2,041)	(34,660)
Contract assets, Balance at End of Period	[1]	29,933	35,587
Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract assets, Additions			462
Contract assets, Balance at End of Period			462
Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities, Balance at Beginning of Period		112,689	179,624
Contract liabilities, Additions		41,962	36,274
Contract liabilities, Deductions		(48,180)	(45,665)
Contract liabilities, Balance at End of Period		106,471	$ 170,233
Accounts Payable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities, Balance at Beginning of Period		13,492
Contract liabilities, Deductions		$ (13,492)

[1] Excludes accounts receivable from other services related to clinical and regulatory activities performed by the Company on behalf of MTPC that are not included in the performance obligations identified under the MTPC Agreement and