Earnings Per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 159,649	$ 144,050	$ 117,804
Less: Preferred stock dividends	8,041	8,352
Net income available to common stockholders	$ 151,608	$ 135,698	$ 117,804
Basic weighted average common shares outstanding	174,971,785	167,347,906	146,186,982
Net effect of dilutive stock options, warrants, restricted stock and convertible debt	1,367,168	1,730,939	1,622,522
Diluted weighted average common shares outstanding	176,338,953	169,078,845	147,809,504
Basic earnings per common share	$ 0.87	$ 0.81	$ 0.81
Diluted earnings per common share	$ 0.86	$ 0.80	$ 0.80