Earnings Per Share - Components of Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 17,368	$ 11,049	$ 33,781	$ 25,001
Weighted-average number of common shares outstanding - basic (shares)	27,080,676	26,839,799	27,012,869	26,808,766
Share-based compensation plans (shares)	1,590,456	1,509,521	1,563,242	1,405,578
Warrants (shares)	299,908	331,344	303,769	307,840
Weighted-average number of common shares - diluted (shares)	28,971,040	28,680,664	28,879,880	28,522,184
Basic earnings per common share (usd per share)	$ 0.64	$ 0.41	$ 1.25	$ 0.93
Diluted earnings per common share (usd per share)	$ 0.60	$ 0.39	$ 1.17	$ 0.88