CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Series A	Preferred Series B	Common Stock	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Preferred Stock	Preferred Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock	Common Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Surplus	Surplus Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings	Retained Earnings Preferred Series A	Retained Earnings Preferred Series B	Retained Earnings Common Stock	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury Stock	Treasury Stock Cumulative Effect, Period of Adoption, Adjusted Balance
Beginning balance at Dec. 31, 2019	$ 4,384,188				$ (28,187)	$ 4,356,001	$ 209,691	$ 209,691	$ 141,423	$ 141,423	$ 3,622,208	$ 3,622,208	$ 443,559				$ (28,187)	$ 415,372	$ (32,214)	$ (32,214)	$ (479)	$ (479)
Beginning balance (in shares) at Dec. 31, 2019									403,278	403,278
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	87,268												87,268
Other comprehensive loss, net of tax	25,648																		25,648
Cash dividends declared:
Cash dividends declared on preferred stock		$ (1,797)	$ (1,375)											$ (1,797)	$ (1,375)
Cash dividends declared on common stock				$ (44,979)												$ (44,979)
Effect of stock incentive plan, net (in shares)									466
Effect of stock incentive plan, net	232								$ 190		1,828		(2,065)								279
Ending balance at Mar. 31, 2020	4,420,998						209,691		$ 141,613		3,624,036		452,424						(6,566)		(200)
Ending balance (in shares) at Mar. 31, 2020									403,744
Beginning balance at Dec. 31, 2020	4,592,120						209,691		$ 141,746		3,637,468		611,158						(7,718)		(225)
Beginning balance (in shares) at Dec. 31, 2020									403,859
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	115,710												115,710
Other comprehensive loss, net of tax	(9,287)																		(9,287)
Cash dividends declared:
Cash dividends declared on preferred stock		$ (1,797)	$ (1,375)											$ (1,797)	$ (1,375)
Cash dividends declared on common stock				$ (45,281)												$ (45,281)
Effect of stock incentive plan, net (in shares)									1,939
Effect of stock incentive plan, net	9,580								$ 689		14,480		(5,764)								175
Ending balance at Mar. 31, 2021	$ 4,659,670						$ 209,691		$ 142,435		$ 3,651,948		$ 672,651						$ (17,005)		$ (50)
Ending balance (in shares) at Mar. 31, 2021									405,798