Stockholders' Equity - Basic and Diluted Net Income Per Common Shares (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity [Abstract]
Net income	$ 8,015	$ 5,762	$ 6,828	$ 6,925	$ 2,027	$ 8,048	$ 8,447	$ 8,462	$ 27,530	$ 26,984	$ 83,786
Weighted average shares of common stock outstanding									21,648,654	21,924,748	22,083,942
Dilutive effect of restricted stock and RSUs									361,869	472,839	425,066
Weighted average shares of common stock and common stock equivalents									22,010,523	22,397,587	22,509,008
Basic	$ 0.37	$ 0.27	$ 0.32	$ 0.32	$ 0.09	$ 0.37	$ 0.38	$ 0.38	$ 1.27	$ 1.23	$ 3.79
Diluted	$ 0.36	$ 0.26	$ 0.31	$ 0.32	$ 0.09	$ 0.36	$ 0.37	$ 0.37	$ 1.25	$ 1.20	$ 3.72