Net Loss per Share - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net loss	$ (72,593)	$ (27,753)
Denominator:
Weighted-average common shares outstanding	68,476,799	45,953,213
Less: weighted-average common shares subject to vesting	(1,394,638)	(1,670,606)
Weighted-average common shares used to compute basic and diluted net loss per share	67,082,161	44,282,607
Net loss per share: basic and diluted	$ (1.08)	$ (0.63)