Schedule of Deferred Revenue Related to Revenue Recognized for Collaborations and Services (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Beginning balance	$ 47,565	$ 750
Upfront and milestone payments	25,000	55,000
Pass through payments	6,016	2,398
Revenue — collaborations and services	(37,734)	(10,583)
Ending balance	$ 40,847	$ 47,565