Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net income	$ 25,614	$ 18,588
Less: income allocable to participating securities	(193)	(232)
Income allocable to common shares	25,421	18,356
Add back: undistributed earnings allocable to participating securities	193	232
Less: undistributed earnings reallocated to participating securities	(189)	(227)
Numerator for diluted earnings per share	$ 25,425	$ 18,361
Denominator:
Weighted average common shares outstanding	50,315,455	50,315,455
Weighted average common shares repurchased	(1,122,261)
Adjustment for vested restricted stock	8,113,993	6,817,454
Shares for calculating basic earnings per share	57,307,187	57,132,909
Dilutive effect of unvested restricted stock	1,218,793	1,229,131
Shares for calculating diluted earnings per share	58,525,980	58,362,040
Earnings per share:
Basic	$ 0.44	$ 0.32
Diluted	$ 0.43	$ 0.31