Net Loss Per Share - Weighted Average Number of Shares Used in Computing Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net loss	$ (7,887)	$ (13,946)	$ (14,449)	$ (11,917)	$ (21,833)	$ (26,366)
Denominator:
Weighted average number of shares of common stock used in computing net loss per share, basic and diluted	40,129,304		36,278,567		40,101,789	36,098,171
Net loss per share, basic and diluted	$ (0.20)		$ (0.40)		$ (0.54)	$ (0.73)