Stockholders' Equity - Basic and Diluted Net Income Per Common Shares (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity [Abstract]
Net income	$ 72,721	$ 4,220	$ 3,376	$ 3,917	$ 6,912	$ 4,652	$ 4,291	$ 4,890	$ 84,235	$ 20,745	$ 27,530
Weighted average shares of common stock outstanding (shares)									21,120,268	21,621,466	21,648,654
Dilutive effect of restricted stock and RSUs (shares)									66,482	469,304	361,869
Weighted average shares of common stock and common stock equivalents (shares)									21,186,750	22,090,770	22,010,523
Basic (usd per share)	$ 3.54	$ 0.20	$ 0.16	$ 0.18	$ 0.32	$ 0.21	$ 0.20	$ 0.23	$ 3.99	$ 0.96	$ 1.27
Diluted (usd per share)	$ 3.53	$ 0.20	$ 0.16	$ 0.18	$ 0.31	$ 0.21	$ 0.19	$ 0.22	$ 3.98	$ 0.94	$ 1.25