Leases - Summary of Operating Lease Costs Included in Research and Development and General and Administrative Expense, as well as Sublease Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease costs	$ 8,067
Short-term lease costs	4,554
Variable lease costs	4,282
Sublease income	(525)	$ (176)
Net lease cost	$ 16,378