Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net loss	$ (71,644)	$ (68,806)	$ (46,205)	$ (27,840)	$ (32,393)	$ (31,806)	$ (186,655)	$ (92,039)
Weighted average shares outstanding, basic and diluted	73,706			58,754			69,720	54,218
Net loss per share, basic and diluted	$ (0.97)			$ (0.47)			$ (2.68)	$ (1.70)