Earnings Per Common Share (Basic and Diluted Earnings Per Common Share) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 443,599	$ 454,918	$ 364,149
Less: Preferred stock dividends	8,063	8,063	8,063
Net income available to common shareholders	435,536	446,855	356,086
Less: Earnings allocated to participating securities	3,687	3,169	2,016
Distributed earnings allocated to common stock	175,540	164,268	143,356
Undistributed earnings allocated to common stock	256,309	279,418	210,714
Net earnings allocated to common stock	$ 431,849	$ 443,686	$ 354,070
Weighted-average shares outstanding for basic earnings per common share	62,741,769	63,704,508	63,693,927
Dilutive effect of stock compensation	700,101	982,208	968,161
Weighted-average shares outstanding for diluted earnings per common share	63,441,870	64,686,716	64,662,088