Net Income Per Common Share - Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Income Per Common 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 income	$ 4,773	$ 2,207	$ 4,151	$ 3,290	$ 6,980	$ 7,441
Basic:
Weighted average shares of common stock and vested, undelivered restricted stock units outstanding	27,532,786		27,640,207		27,768,224	27,722,521
Diluted:
Weighted average shares of common stock and vested, undelivered restricted stock units outstanding	27,532,786		27,640,207		27,768,224	27,722,521
Effect of potentially dilutive shares	630,127		591,538		535,844	503,469
Total weighted average shares of common stock and vested, undelivered restricted stock units outstanding and potentially dilutive shares	28,162,913		28,231,745		28,304,068	28,225,990
Net Income Per Share:
Basic net income per share	$ 0.17		$ 0.15		$ 0.25	$ 0.27
Diluted net income per share	$ 0.17		$ 0.15		$ 0.25	$ 0.26