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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings for basic and diluted earnings per common share:
Net income	$ 93,865	$ 99,673	$ 292,250	$ 261,580
Less: Preferred stock dividends	1,968	1,968	5,906	5,884
Undistributed Earnings, Basic	91,897	97,705	286,344	255,696
Net income available to common shareholders	91,897	97,705	286,344	255,696
Less: Earnings applicable to participating restricted stock	455	245	1,425	656
Less: Earnings applicable to participating securities	455	245	1,425	656
Earnings applicable to common shareholders	91,442	97,460	284,919	255,040
Earnings applicable to common shareholders	$ 91,442	$ 97,460	$ 284,919	$ 255,040
Shares:
Weighted average common shares outstanding - basic (in shares)	91,559	91,959	91,554	91,912
Stock options and restricted stock (in shares)	315	249	329	309
Weighted-average common shares outstanding - diluted (in shares)	91,874	92,208	91,883	92,221
Earnings per common share:
Basic (in dollars per share)	$ 1.00	$ 1.06	$ 3.11	$ 2.77
Diluted (in dollars per share)	$ 1.00	$ 1.06	$ 3.10	$ 2.77