Earnings Per Share - Components of Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 11,049	$ 10,233	$ 25,001	$ 18,374
Weighted-average number of common shares outstanding - basic	26,839,799	26,724,499	26,808,766	26,705,620
Share-based compensation plans	1,509,521	997,012	1,405,578	924,398
Warrants	331,344	260,893	307,840	251,796
Weighted-average number of common shares - diluted	28,680,664	27,982,404	28,522,184	27,881,814
Basic earnings per common share	$ 0.41	$ 0.38	$ 0.93	$ 0.69
Diluted earnings per common share	$ 0.39	$ 0.37	$ 0.88	$ 0.66