Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock, Common [Member]	Deferred Compensation [Member]	Accumulated Other Total Comprehensive Earnings, net [Member]
Beginning Balance at Dec. 31, 2020	$ 1,678,190	$ 1,422	$ 669,644	$ 836,729	$ (9,126)	$ 9,126	$ 170,395
Beginning Balance, Shares at Dec. 31, 2020		142,161,834
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2020					(938,591)
NET EARNINGS	227,562			227,562
Stock option exercises/stock unit conversions/restricted stock activity	3,985	$ 3	3,982
Stock option exercises/stock unit conversions/restricted stock activity, Shares		370,282
Cash dividends declared	(82,616)			(82,616)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	(71,142)						(71,142)
Shares purchased in connection with directors’ deferred compensation plan, net					$ (964)	964
Shares purchased in connection with directors’ deferred compensation plan, net, Shares					1,694
Stock-based compensation expense	3,245		3,245
Ending Balance at Dec. 31, 2021	1,759,224	$ 1,425	676,871	981,675	$ (10,090)	10,090	99,253
Ending Balance, Shares at Dec. 31, 2021		142,532,116
Treasury Stock, Ending Balance, Shares at Dec. 31, 2021					(936,897)
NET EARNINGS	234,475			234,475
Stock option exercises/stock unit conversions/restricted stock activity	6,215	$ 4	6,211
Stock option exercises/stock unit conversions/restricted stock activity, Shares		370,314
Cash dividends declared	(94,205)			(94,205)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	(634,481)						(634,481)
Shares purchased in connection with directors’ deferred compensation plan, net					$ (945)	945
Shares purchased in connection with directors’ deferred compensation plan, net, Shares					7,687
Stock-based compensation expense	3,958		3,958
Shares repurchased and retired under stock repurchase authorization	(9,449)	$ (2)	(9,447)
Shares repurchased and retired under stock repurchase authorization, shares		(244,559)
Ending Balance at Dec. 31, 2022	$ 1,265,737	$ 1,427	677,593	1,121,945	$ (11,035)	11,035	(535,228)
Ending Balance, Shares at Dec. 31, 2022		142,657,871
Treasury Stock, Ending Balance, Shares at Dec. 31, 2022	929,210				(929,210)
NET EARNINGS	$ 198,977			198,977
Stock option exercises/stock unit conversions/restricted stock activity	2,132	$ 1	2,131
Stock option exercises/stock unit conversions/restricted stock activity, Shares		160,405
Cash dividends declared	(101,397)			(101,397)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	131,930						131,930
Shares purchased in connection with directors’ deferred compensation plan, net					$ (820)	820
Shares purchased in connection with directors’ deferred compensation plan, net, Shares					942
Stock-based compensation expense	4,256		4,256
Shares repurchased and retired under stock repurchase authorization	(2,735)	$ (1)	(2,734)
Shares repurchased and retired under stock repurchase authorization, shares		(101,337)
Ending Balance at Dec. 31, 2023	$ 1,498,900	$ 1,427	$ 681,246	$ 1,219,525	$ (11,855)	$ 11,855	$ (403,298)
Ending Balance, Shares at Dec. 31, 2023		142,716,939
Treasury Stock, Ending Balance, Shares at Dec. 31, 2023	930,152				(930,152)