Earnings Per Common Share (Earnings Per Share Basic And Diluted) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings for basic and diluted earnings per common share:
Net income	$ 98,649	$ 81,682	$ 198,385	$ 161,907
Less: Preferred stock dividends	1,969	1,969	3,938	3,916
Undistributed Earnings, Basic	96,680	79,713	194,447	157,991
Net income available to common shareholders	96,680	79,713	194,447	157,991
Less: Earnings applicable to participating restricted stock	487	224	964	418
Less: Earnings applicable to participating securities	487	224	964	418
Earnings applicable to common shareholders	96,193	79,489	193,483	157,573
Earnings applicable to common shareholders	$ 96,193	$ 79,489	$ 193,483	$ 157,573
Effect of dilutive securities:
Weighted average common shares outstanding - basic (in shares)	91,534	91,893	91,550	91,913
Stock options and restricted stock (in shares)	321	280	348	323
Weighted-average common shares outstanding - diluted (in shares)	91,855	92,173	91,898	92,236
Earnings per common share:
Basic (in dollars per share)	$ 1.05	$ 0.87	$ 2.11	$ 1.71
Diluted (in dollars per share)	$ 1.05	$ 0.86	$ 2.11	$ 1.71