CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred stock	Common stock	Surplus	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, 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	0			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
Common stock issued for:
New issuance, net of costs	285,729			1,612	174,214	109,903
Exercise of stock options and warrants	4,886			123	5,067	(304)
Restricted stock awards	0			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)
Common stock issued for:
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2022-02
Net income	$ 622,626						622,626
Other comprehensive income (loss), net of tax	66,405								66,405
Cash dividends declared on common stock	(97,726)						(97,726)
Dividends on preferred stock	(27,964)						(27,964)
Stock-based compensation	33,495				33,495
Exercise of stock options and warrants	2,242			56	2,186
Restricted stock awards	(1,913)			307	(307)	(1,913)
Employee stock purchase plan	3,329			46	3,283
Director compensation plan	2,738			63	2,675
Balance at end of period at Dec. 31, 2023	$ 5,399,526	$ (544)	$ 412,500	$ 61,269	$ 1,943,806	$ (2,217)	$ 3,345,399	$ (544)	$ (361,231)