Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 35,391	$ 31,634	$ 104,746	$ 89,365
Less: Preferred stock dividends	2,010		6,342
Net income available to common stockholders	$ 33,381	$ 31,634	$ 98,404	$ 89,365
Basic weighted average common shares outstanding	167,260,386	144,759,887	165,229,206	142,949,134
Net effect of dilutive stock options, warrants, restricted stock and convertible debt	1,623,741	1,686,555	1,695,637	1,520,683
Diluted weighted average common shares outstanding	168,884,127	146,446,442	166,924,843	144,469,817
Basic	$ 0.20	$ 0.22	$ 0.60	$ 0.63
Diluted	$ 0.20	$ 0.22	$ 0.59	$ 0.62