Earnings Per Common Share (Earnings Per Share Basic And Diluted) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings for basic and diluted earnings per common share:
Net income	$ 64,496	$ 51,817	$ 185,546	$ 149,467
Less: Preferred stock dividends	2,024	2,024	6,072	6,072
Undistributed Earnings, Basic	62,472	49,793	179,474	143,395
Net income available to common shareholders	62,472	49,793	179,474	143,395
Less: Earnings applicable to participating securities	46	159	212	468
Less: Earnings applicable to participating securities	46	159	212	468
Earnings applicable to common shareholders	62,426	49,634	179,262	142,927
Earnings applicable to common shareholders	$ 62,426	$ 49,634	$ 179,262	$ 142,927
Shares:
Weighted average common shares outstanding - basic (in shares)	92,125	91,365	92,003	91,298
Effect of dilutive securities:
Stock options and restricted stock (in shares)	372	465	403	452
Warrants (in shares)	6	27	6	26
Weighted-average common shares outstanding - diluted (in shares)	92,503	91,857	92,412	91,776
Earnings per common share:
Basic (in dollars per share)	$ 0.68	$ 0.54	$ 1.95	$ 1.57
Diluted (in dollars per share)	$ 0.67	$ 0.54	$ 1.94	$ 1.56