Net Loss Per Share - Summary of Basic And Diluted Net Loss Per Share Attributable To Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net loss	$ (8,348)	$ (6,897)	$ (16,149)	$ (14,090)
Accretion of issuance costs related to redeemable convertible preferred stock	(429)	(33)	(456)	(51)
Accrued dividends on redeemable convertible preferred stock	(2,187)	(1,476)	(3,957)	(2,728)
Net loss attributable to common stockholders	$ (10,964)	$ (8,406)	$ (20,562)	$ (16,869)
Weighted-average common shares outstanding—basic and diluted	1,488,489	1,429,484	1,488,489	1,413,935
Net loss per share attributable to common stockholders—basic and diluted	$ (7.37)	$ (5.88)	$ (13.81)	$ (11.93)