Collaborations - Summary of Changes in Accounts Receivable and Contract Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Accounts receivable:
Accounts receivable, Balance at Beginning of Period	$ 4,620	$ 7,547
Accounts receivable, Additions	102,203	11,379
Accounts receivable, Deductions	(105,606)	(15,327)
Accounts receivable, Balance at End of Period	1,217	3,599
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	28,810	55,932
Deferred revenue, Additions	87,477	3,000
Deferred revenue, Deductions	(36,673)	(23,788)
Deferred revenue, Balance at End of Period	$ 79,614	$ 35,144