Stockholders' Equity - Basic and Diluted Net Income Per Common Shares (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Equity [Abstract]
Net income	$ 4,652	$ 5,762	$ 13,833	$ 19,515
Weighted average shares of common stock outstanding	21,651,347	21,629,289	21,643,951	21,653,692
Dilutive effect of restricted stock and RSUs	484,207	289,949	445,941	262,371
Weighted average shares of common stock and common stock equivalents	22,135,554	21,919,238	22,089,892	21,916,063
Basic	$ 0.21	$ 0.27	$ 0.64	$ 0.90
Diluted	$ 0.21	$ 0.26	$ 0.63	$ 0.89