CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - 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)
Beginning balance 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	127,391						127,391
Other comprehensive income (loss), net of tax	(120,091)								(120,091)
Cash dividends declared on common stock	(19,461)						(19,461)
Dividends on preferred stock	(6,991)						(6,991)
Stock-based compensation	7,891				7,891
Common stock issued for:
Exercise of stock options and warrants	3,358			79	3,279
Restricted stock awards	0			52	(52)
Employee stock purchase plan	842			10	832
Director compensation plan	629			58	571
Ending balance at Mar. 31, 2022	4,492,256		412,500	59,091	1,698,093	(109,903)	2,548,474		(115,999)
Beginning balance at Dec. 31, 2021	4,498,688		412,500	58,892	1,685,572	(109,903)	2,447,535		4,092
Ending balance at Dec. 31, 2022	$ 4,796,838	$ (544)	412,500	60,797	1,902,474	(304)	2,849,007	$ (544)	(427,636)
Common stock issued for:
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2022-02 [Member]
Net income	$ 180,198						180,198
Other comprehensive income (loss), net of tax	60,200								60,200
Cash dividends declared on common stock	(24,407)						(24,407)
Dividends on preferred stock	(6,991)						(6,991)
Stock-based compensation	8,295				8,295
Exercise of stock options and warrants	2,216			54	2,162
Restricted stock awards	(1,662)			275	(275)	(1,662)
Employee stock purchase plan	694			9	685
Director compensation plan	669			63	606
Ending balance at Mar. 31, 2023	$ 5,015,506		$ 412,500	$ 61,198	$ 1,913,947	$ (1,966)	$ 2,997,263		$ (367,436)