Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Capital Surplus [Member]	Capital Surplus [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Treasury Stock [Member]	Treasury Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Deferred Compensation [Member]	Deferred Compensation [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Accumulated Other Total Comprehensive Earnings, net [Member]	Accumulated Other Total Comprehensive Earnings, net [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Beginning Balance at Dec. 31, 2018	$ 1,053,295			$ 678		$ 443,114		$ 606,658			$ (7,507)		$ 7,507		$ 2,845
Beginning Balance, Shares at Dec. 31, 2018				67,753,133
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2018											(467,811)
NET EARNINGS	164,812							164,812
Stock option exercises	4,293			$ 2		4,291
Stock option exercises, Shares				241,725
Restricted stock grant, net	1,782					1,782
Restricted stock grant net, Shares				56,687
Cash dividends declared	(63,135)							(63,135)
Minimum liability pension adjustment, net of related income taxes	1,324														1,324
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	63,337														63,337
Shares purchased in connection with directors’ deferred compensation plan, net											$ (715)		715
Shares purchased in connection with directors’ deferred compensation plan, net, Shares											4,742
Stock option expense	1,489					1,489
Two-for-one stock split in the form of 100% stock dividend				$ 679				(679)
Two-for-one stock spllit in the form of a 100% stock dividend, shares				67,840,210							(464,339)
Ending Balance at Dec. 31, 2019	1,227,197		$ 1,226,731	$ 1,359	$ 1,359	450,676	$ 450,676	707,656		$ 707,190	$ (8,222)	$ (8,222)	8,222	$ 8,222	67,506	$ 67,506
Ending Balance, Shares at Dec. 31, 2019				135,891,755	135,891,755
Treasury Stock, Ending Balance, Shares at Dec. 31, 2019											(927,408)	(927,408)
Cumulative effect of adopting ASC 326 on January 1, 2020, net of related income taxes		$ (466)							$ (466)
NET EARNINGS	202,034							202,034
Stock option exercises	4,717			$ 3		4,714
Stock option exercises, Shares				295,093
Restricted stock grant, net	672					672
Restricted stock grant net, Shares				24,214
Cash dividends declared	(72,495)							72,495
Stock issued in acquisition	220,273			$ 63		220,210
Stock issued in acquisition, Shares				6,275,574
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	102,889														102,889
Shares purchased in connection with directors’ deferred compensation plan, net											$ 904		(904)
Shares purchased in connection with directors’ deferred compensation plan, net, Shares											11,183
Stock option expense	1,377					1,377
Shares repurchased and retired under stock repurchase authorization	8,008			$ 3		8,005
Shares repurchased and retired under stock repurchase authorization, shares				324,802
Ending Balance at Dec. 31, 2020	$ 1,678,190			$ 1,422		669,644		836,729			$ (9,126)		9,126		170,395
Ending Balance, Shares at Dec. 31, 2020				142,161,834
Treasury Stock, Ending Balance, Shares at Dec. 31, 2020	938,591										(938,591)
NET EARNINGS	$ 227,562							227,562
Stock option exercises	5,905			$ 3		5,902
Stock option exercises, Shares				345,829
Restricted stock grant, net	9					9
Restricted stock grant net, Shares				24,453
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 option expense	1,316					1,316
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										(936,897)