Stockholders' Equity - Basic and Diluted Net Income Per Common Shares (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Equity [Abstract]
Net income	$ 4,220	$ 4,652	$ 11,515	$ 13,833
Weighted average shares of common stock outstanding (shares)	21,301,311	21,651,347	21,623,612	21,643,951
Dilutive effect of restricted stock and RSUs (shares)	51,527	484,207	63,914	445,941
Weighted average shares of common stock and common stock equivalents (shares)	21,352,838	22,135,554	21,687,526	22,089,892
Basic net income per common share (usd per share)	$ 0.20	$ 0.21	$ 0.53	$ 0.64
Diluted net income per common share (usd per share)	$ 0.20	$ 0.21	$ 0.53	$ 0.63