Net Income (Loss) per Share - Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ 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 - basic and diluted	$ (1,013)	$ (30,745)	$ (23,301)	$ (16,509)	$ (25,068)	$ (28,922)	$ (55,059)	$ (70,499)
Weighted-average common shares outstanding:
Weighted average number of shares outstanding basic and diluted	50,114,710			46,885,424			50,031,615	46,803,659
Net loss per share, Basic and Diluted	$ (0.02)			$ (0.35)			$ (1.10)	$ (1.51)