CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Series E Preferred Stock	Preferred stock	Preferred stock Series E Preferred Stock	Common stock	Surplus	Surplus Series E Preferred Stock	Treasury stock	Retained earnings	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss)
Balance at beginning of period at Dec. 31, 2019	$ 3,691,250	$ (26,717)		$ 125,000		$ 57,951	$ 1,650,278		$ (6,931)	$ 1,899,630	$ (26,717)	$ (34,678)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	292,990									292,990
Other comprehensive income (loss), net of tax	50,060											50,060
Cash dividends declared on common stock	(64,513)									(64,513)
Dividends on preferred stock	(21,377)									(21,377)
Common stock repurchased under authorized program	(92,055)								(92,055)
Stock-based compensation	(4,938)						(4,938)
Issuance of Series E preferred stock			$ 277,613		$ 287,500			$ (9,887)
Common stock issued for:
New issuance, net of cost			$ 277,613		$ 287,500			$ (9,887)
Exercise of stock options and warrants	9,038					229	9,434		(625)
Restricted stock awards	(752)					201	(201)		(752)
Employee stock purchase plan	2,978					72	2,906
Director compensation plan	2,418					20	2,398
Balance at end of period at Dec. 31, 2020	4,115,995			412,500		58,473	1,649,990		(100,363)	2,080,013		15,382
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	466,151									466,151
Other comprehensive income (loss), net of tax	(11,290)											(11,290)
Cash dividends declared on common stock	(70,663)									(70,663)
Dividends on preferred stock	(27,966)									(27,966)
Common stock repurchased under authorized program	(9,540)								(9,540)
Stock-based compensation	16,177						16,177
Common stock issued for:
Exercise of stock options and warrants	14,035					327	13,708
Restricted stock awards						20	(20)
Employee stock purchase plan	3,325					48	3,277
Director compensation plan	2,464					24	2,440
Balance at end of period at Dec. 31, 2021	4,498,688			412,500		58,892	1,685,572		(109,903)	2,447,535		4,092
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	509,682									509,682
Other comprehensive income (loss), net of tax	(431,728)											(431,728)
Cash dividends declared on common stock	(80,246)									(80,246)
Dividends on preferred stock	(27,964)									(27,964)
Stock-based compensation	31,748						31,748
Issuance of Series E preferred stock	285,729					1,612	174,214		109,903
Common stock issued for:
New issuance, net of cost	285,729					1,612	174,214		109,903
Exercise of stock options and warrants	4,886					123	5,067		(304)
Restricted stock awards						69	(69)
Employee stock purchase plan	3,386					42	3,344
Director compensation plan	2,657					59	2,598
Balance at end of period at Dec. 31, 2022	$ 4,796,838			$ 412,500		$ 60,797	$ 1,902,474		$ (304)	$ 2,849,007		$ (427,636)