Earnings Per Common 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 Reconciliation
Net income available to common shareholders	$ 37,230	$ 31,991	$ 71,620	$ 62,332
Basic weighted average number of common shares outstanding (in shares)	254,381,170	232,565,404	254,228,260	232,452,716
Plus: Common stock equivalents (in shares)	390,043	21,212	347,613	5,032
Diluted weighted average number of common shares outstanding (in shares)	254,771,213	232,586,616	254,575,873	232,457,748
Earnings per common share:
Basic (in usd per share)	$ 0.15	$ 0.14	$ 0.28	$ 0.27
Diluted (in usd per share)	$ 0.15	$ 0.14	$ 0.28	$ 0.27
Anti-dilutive common stock options and warrants (in shares)	4,600,000	6,100,000	4,600,000	6,100,000