Earnings Per Share - Computation of Basic and Diluted Net Income Per Share (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
Numerator:
Net income	$ 3,847	$ 2,690	$ 15,788	$ 3,157
Less: income allocable to participating securities	(49)		(205)
Income allocable to common shares	3,798	2,690	15,583	3,157
Add back: undistributed earnings allocable to participating securities	49		205
Less: undistributed earnings reallocated to participating securities	(49)		(200)
Numerator for diluted earnings per share	$ 3,798	$ 2,690	$ 15,588	$ 3,157
Denominator:
Weighted average common shares outstanding	50,315,455	51,056,462	50,315,455	49,040,344
Adjustment for vested restricted stock	6,735,229		5,972,524
Shares for calculating basic EPS	57,050,684	51,056,462	56,287,979	49,040,344
Dilutive effect of unvested restricted stock	1,317,146	1,921,589	1,483,701	2,182,704
Shares for calculating diluted EPS	58,367,830	52,978,051	57,771,680	51,223,048
Net income per share:
Basic	$ 0.07	$ 0.05	$ 0.28	$ 0.06
Diluted	$ 0.07	$ 0.05	$ 0.27	$ 0.06