Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share Reconciliation
Net income available to common shareholders	$ 48,268	$ 37,230	$ 92,566	$ 71,620
Basic weighted average number of common shares outstanding (in shares)	263,958,292	254,381,170	263,878,103	254,228,260
Plus: Common stock equivalents (in shares)	819,950	390,043	784,760	347,613
Diluted weighted average number of common shares outstanding (in shares)	264,778,242	254,771,213	264,662,863	254,575,873
Earnings per common share:
Basic (usd per share)	$ 0.18	$ 0.15	$ 0.35	$ 0.28
Diluted (usd per share)	$ 0.18	$ 0.15	$ 0.35	$ 0.28
Anti-dilutive common stock options and warrants (in shares)	3,300,000	4,600,000	3,300,000	4,600,000