Collaborations - Summary of Changes in Contract Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	$ 55,932	$ 59,868
Deferred revenue, Additions	3,000	3,000
Deferred revenue, Deductions	(23,788)	(16,604)
Deferred revenue, Balance at End of Period	$ 35,144	$ 46,264