Stockholders' Equity - Basic and Diluted Net Income Per Common Shares (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Equity [Abstract]
Net income	$ 4,291	$ 6,828	$ 9,181	$ 13,753
Weighted average shares of common stock outstanding	21,642,163	21,644,281	21,640,191	21,666,096
Dilutive effect of restricted stock and RSUs	457,628	182,868	433,063	255,646
Weighted average shares of common stock and common stock equivalents	22,099,791	21,827,149	22,073,254	21,921,742
Basic	$ 0.20	$ 0.32	$ 0.42	$ 0.63
Diluted	$ 0.19	$ 0.31	$ 0.42	$ 0.63