Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Deferred Compensation [Member]	Accumulated Other Comprehensive Earnings (Loss) [Member]
Beginning Balance at Dec. 31, 2023	$ 1,498,900	$ 1,427	$ 681,246	$ 1,219,525	$ (11,855)	$ 11,855	$ (403,298)
Beginning Balance, Shares at Dec. 31, 2023		142,716,939
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2023					(930,152)
Net Income (Loss)	105,882			105,882
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited)	1,785	$ 1	1,784
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited), Shares		131,970
Cash dividends declared	(51,461)			(51,461)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes (unaudited)	(38,259)						(38,259)
Shares purchased in connection with directors' deferred compensation plan, net (unaudited)					$ (523)	523
Shares purchased in connection with directors' deferred compensation plan, net (unaudited), Shares					(3,983)
Stock- based compensation expense (unaudited)	2,179		2,179
Ending Balance at Jun. 30, 2024	$ 1,519,026	$ 1,428	685,209	1,273,946	$ (12,378)	12,378	(441,557)
Ending Balance, Shares at Jun. 30, 2024		142,848,909
Treasury Stock, Ending Balance, Shares at Jun. 30, 2024	(934,135)				(934,135)
Beginning Balance at Mar. 31, 2024	$ 1,491,367	$ 1,428	683,997	1,247,169	$ (12,120)	12,120	(441,227)
Beginning Balance, Shares at Mar. 31, 2024		142,817,159
Treasury Stock, Beginning Balance, Shares at Mar. 31, 2024					(931,427)
Net Income (Loss)	52,485			52,485
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited)	162		162
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited), Shares		31,750
Cash dividends declared	(25,708)			(25,708)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes (unaudited)	(330)						(330)
Shares purchased in connection with directors' deferred compensation plan, net (unaudited)					$ (258)	258
Shares purchased in connection with directors' deferred compensation plan, net (unaudited), Shares					(2,708)
Stock- based compensation expense (unaudited)	1,050		1,050
Ending Balance at Jun. 30, 2024	$ 1,519,026	$ 1,428	685,209	1,273,946	$ (12,378)	12,378	(441,557)
Ending Balance, Shares at Jun. 30, 2024		142,848,909
Treasury Stock, Ending Balance, Shares at Jun. 30, 2024	(934,135)				(934,135)
Beginning Balance at Dec. 31, 2024	$ 1,606,560	$ 1,429	689,338	1,340,082	$ (12,905)	12,905	(424,289)
Beginning Balance, Shares at Dec. 31, 2024		142,944,704
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2024	(929,735)				(929,735)
Net Income (Loss)	$ 128,004			128,004
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited)	1,479	$ 2	1,477
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited), Shares		132,915
Cash dividends declared	(52,982)			(52,982)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes (unaudited)	50,833						50,833
Shares purchased in connection with directors' deferred compensation plan, net (unaudited)					$ (689)	689
Shares purchased in connection with directors' deferred compensation plan, net (unaudited), Shares					(47)
Stock- based compensation expense (unaudited)	3,458		3,458
Ending Balance at Jun. 30, 2025	$ 1,737,352	$ 1,431	694,273	1,415,104	$ (13,594)	13,594	(373,456)
Ending Balance, Shares at Jun. 30, 2025		143,077,619
Treasury Stock, Ending Balance, Shares at Jun. 30, 2025	(929,782)				(929,782)
Beginning Balance at Mar. 31, 2025	$ 1,680,261	$ 1,430	692,068	1,375,652	$ (13,263)	13,263	(388,889)
Beginning Balance, Shares at Mar. 31, 2025		143,019,433
Treasury Stock, Beginning Balance, Shares at Mar. 31, 2025					(928,353)
Net Income (Loss)	66,658			66,658
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited)	675	$ 1	674
Stock option exercises/ stock unit conversions/ restricted stock activity (unaudited), Shares		58,186
Cash dividends declared	(27,206)			(27,206)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes (unaudited)	15,433						15,433
Shares purchased in connection with directors' deferred compensation plan, net (unaudited)					$ (331)	331
Shares purchased in connection with directors' deferred compensation plan, net (unaudited), Shares					(1,429)
Stock- based compensation expense (unaudited)	1,531		1,531
Ending Balance at Jun. 30, 2025	$ 1,737,352	$ 1,431	$ 694,273	$ 1,415,104	$ (13,594)	$ 13,594	$ (373,456)
Ending Balance, Shares at Jun. 30, 2025		143,077,619
Treasury Stock, Ending Balance, Shares at Jun. 30, 2025	(929,782)				(929,782)