Net Loss Per Share - Computation of Numerators and Denominators Used in Basic and Diluted Net Loss Per Share Amounts (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss	$ (8,109)	$ (13,648)	$ 14,360	$ (8,505)	$ (10,223)	$ 6,030	$ (7,397)	$ (12,698)
Denominator:
Denominator for basic loss per share— weighted average shares	75,750			73,311			75,226	72,979
Denominator for dilutive loss per share	75,750			73,311			75,226	72,979
Net loss per share attributable to common stockholders, basic	$ (0.11)			$ (0.12)			$ (0.10)	$ (0.17)
Net loss per share attributable to common stockholders, diluted	$ (0.11)			$ (0.12)			$ (0.10)	$ (0.17)