Basic and Diluted Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net loss attributable to common stockholders	$ (16,033)	$ (12,706)	$ (37,334)	$ (41,568)
Weighted-average number of shares used in computing net loss per share, basic and diluted	22,072,243	12,022,620	18,199,575	11,992,240
Net loss available for common stockholders per share, basic and diluted	$ (0.73)	$ (1.06)	$ (2.05)	$ (3.47)