Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2021	$ 4,718,628	$ 353,402	$ 3,149,955	$ 1,390,777	$ (4,888)	$ (170,618)
Beginning Balance, shares at Dec. 31, 2021		141,360,266
Net income	81,664	$ 0	0	81,664	0	0
Other comprehensive income (loss), net of tax	(136,804)	0	0	0	(136,804)	0
Total Comprehensive income (loss), net of tax	(55,140)
Stock based compensation expense	2,061	0	2,061	0	0	0
Stock grant forfeiture	0	$ 0	223	0	0	(223)
Stock grant forfeiture, shares		0
Purchase of treasury stock	(26,061)	$ 0	0	0	0	(26,061)
Cash dividends	(49,266)	0	0	(49,266)	0	0
Net issuance of common stock under stock-based compensation plans	4,918	$ 1,056	3,862	0	0	0
Net issuance of common stock under stock-based compensation plans, shares		422,766
Ending Balance at Mar. 31, 2022	4,595,140	$ 354,458	3,156,101	1,423,175	(141,692)	(196,902)
Ending Balance, shares at Mar. 31, 2022		141,783,032
Beginning Balance at Dec. 31, 2022	4,516,193	$ 355,029	3,168,874	1,575,426	(332,732)	(250,404)
Beginning Balance, shares at Dec. 31, 2022		142,011,560
Net income	98,307	$ 0	0	98,307	0	0
Other comprehensive income (loss), net of tax	38,602	0	0	0	38,602	0
Total Comprehensive income (loss), net of tax	136,909
Stock based compensation expense	2,713	0	2,713	0	0	0
Stock grant forfeiture	0	$ 0	58	0	0	(58)
Stock grant forfeiture, shares		0
Purchase of treasury stock	(1,374)	$ 0	0	0	0	(1,374)
Cash dividends	(48,720)	0	0	(48,720)	0	0
Net issuance of common stock under stock-based compensation plans	816	$ 566	250	0	0	0
Net issuance of common stock under stock-based compensation plans, shares		226,486
Ending Balance at Mar. 31, 2023	$ 4,606,537	$ 355,595	$ 3,171,895	$ 1,625,013	$ (294,130)	$ (251,836)
Ending Balance, shares at Mar. 31, 2023		142,238,046