Stockholders' Equity and Stock Based Compensation - Basic and Diluted Net Income Per Common Shares (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
Net income	$ 4,058	$ 4,220	$ 10,953	$ 11,515
Weighted average shares of common stock outstanding (shares)	20,517,419	21,301,311	20,581,586	21,623,612
Dilutive effect of restricted stock and RSUs and the ESPP (shares)	14,926	14,374	14,464	15,361
Weighted average shares of common stock and common stock equivalents (shares)	20,532,345	21,315,685	20,596,050	21,638,973
Basic net income per common share (usd per share)	$ 0.20	$ 0.20	$ 0.53	$ 0.53
Diluted net income per common share (usd per share)	$ 0.20	$ 0.20	$ 0.53	$ 0.53