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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings for basic and diluted earnings per common share:
Net income	$ 69,281	$ 93,865	$ 160,577	$ 292,250
Less: Preferred stock dividends	1,968	1,968	5,906	5,906
Undistributed Earnings, Basic	67,313	91,897	154,671	286,344
Undistributed Earnings, Diluted, Total	67,313	91,897	154,671	286,344
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	423	455	913	1,425
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted	423	455	913	1,425
Earnings applicable to common shareholders	66,890	91,442	153,758	284,919
Earnings applicable to common shareholders	$ 66,890	$ 91,442	$ 153,758	$ 284,919
Shares:
Weighted-average common shares outstanding - basic	89,630	91,559	90,076	91,554
Effect of dilutive securities	108	315	159	329
Weighted-average common shares outstanding - diluted	89,738	91,874	90,235	91,883
Earnings per common share (1):
Basic	$ 0.75	$ 1.00	$ 1.71	$ 3.11
Diluted	$ 0.75	$ 1.00	$ 1.70	$ 3.10