Earnings Per Share - Reconciles Numerators and Denominators of Basic Earnings Per Share with Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator for Earnings per Share-Basic:
Net income	$ 20,581	$ 18,635	$ 53,733	$ 49,658
Less: Income allocated to participating shares	68	81	167	204
Net Income Allocated to Shareholders	20,513	18,554	53,566	49,454
Net Income (Loss) Available to Common Stockholders, Diluted	$ 20,581	$ 18,635	$ 53,733	$ 49,658
Denominators:
Weighted Average Shares Outstanding-Basic	34,687,487	34,660,007	34,674,453	33,527,549
Add: Potentially dilutive shares	81,018	32,985	72,724	33,980
Denominator for Treasury Stock Method-Diluted (in shares)	34,768,505	34,692,992	34,747,177	33,561,529
Weighted Average Shares Outstanding-Basic	34,687,487	34,660,007	34,674,453	33,527,549
Add: Average participating shares outstanding	114,746	151,972	108,414	138,441
Denominator for Two-Class Method-Diluted (in shares)	34,802,233	34,811,979	34,782,867	33,665,990
Earnings per share—basic (in dollars per share)	$ 0.59	$ 0.54	$ 1.55	$ 1.48
Earnings per share—diluted (in dollars per share)	0.59	0.54	1.54	1.48
Anti-dilutive warrants - exercise price (in dollars per share)	$ 31.53	$ 31,530.00	$ 31.53	$ 31,530.00
Warrants
Denominators:
Anti-dilutive excluded from potentially dilutive shares	517,012	517,012	517,012	517,012
Stock Options
Denominators:
Anti-dilutive excluded from potentially dilutive shares	0	155,500	0	155,500
Restricted Stock
Denominators:
Anti-dilutive excluded from potentially dilutive shares	146,695	118,987	134,983	104,461