License, Collaboration and Other Significant Agreements - Schedule of Changes in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities, Balance at End of Period		$ 77,685
Accounts Receivable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract assets, Balance at Beginning of Period	[1]	15,822	$ 1,587
Contract assets, Additions	[1]	71,639	30,387
Contract assets, Deductions	[1]	(2,895)	(2,041)
Contract assets, Balance at End of Period	[1]	84,566	29,933
Prepaid Expenses and Other Current Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract assets, Additions		546
Contract assets, Balance at End of Period		546
Accrued Expenses and Other Current Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities, Additions		615
Contract liabilities, Balance at End of Period		615
Deferred Revenue
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contract liabilities, Balance at Beginning of Period		72,950	112,689
Contract liabilities, Additions		65,209	41,962
Contract liabilities, Deductions		(60,474)	(48,180)
Contract liabilities, Balance at End of Period		$ 77,685	106,471
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 as of March 31, 2019 and 2020 and December 31, 2018 and 2019. Also excludes accounts receivable related to amounts due to the Company from product sales which are included in the accompanying unaudited condensed consolidated balance sheet as of March 31, 2020 and December 31, 2019.