Net Loss per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator
Net loss attributable to common stockholders									$ (32,231)	$ (20,703)	$ (18,479)
Denominator
Weighted-average common stock outstanding (in shares)									10,341,809	1,796,233	1,706,654
Less: weighted-average common shares subject to repurchase (in shares)									(156,968)	(20,123)	(31,875)
Weighted-average shares used in computing net loss per share attributable to common stockholder, basic and diluted (in shares)									10,184,841	1,776,110	1,674,779
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (1.37)	$ (6.15)	$ (3.76)	$ (2.48)	$ (2.41)	$ (3.24)	$ (3.61)	$ (3.16)	$ (11.66)	$ (11.03)