Net Income Per Share - Components of Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator
Net income	$ 9,162	$ 8,941	$ 8,796	$ 6,813	$ 7,141	$ 8,061	$ 5,416	$ 3,254	$ 33,712	$ 23,872	$ 351
Denominator
Weighted average common shares outstanding, basic									35,024	34,392	34,366
Options to purchase common stock									680	612	300
PSUs, RSUs and RSAs									298	208	46
Weighted average common shares outstanding, diluted									36,002	35,212	34,712
Net income per share
Basic									$ 0.96	$ 0.69	$ 0.01
Diluted	$ 0.25	$ 0.25	$ 0.25	$ 0.19	$ 0.21	$ 0.23	$ 0.15	$ 0.09	$ 0.94	$ 0.68	$ 0.01