Net Loss Per Share - Computation of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss	$ (6,753)	$ (5,698)	$ (3,169)	$ (2,289)	$ (5,318)	$ (6,002)	$ (15,620)	$ (13,609)
Denominator:
Weighted average shares outstanding, basic and diluted	26,728,205			24,171,811			26,150,236	24,074,565
Net loss per share, basic and diluted	$ (0.25)			$ (0.09)			$ (0.60)	$ (0.57)