Condensed Financial Information - Parent Company - Condensed Statements of Earnings (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income:
Total interest income		$ 376,405	$ 364,128	$ 319,192
Expenses:
Salaries and employee benefits		142,042	135,123	112,336
EARNINGS BEFORE INCOME TAXES		271,970	242,365	198,032
Income tax benefit		(44,408)	(40,331)	(33,220)
NET EARNINGS		227,562	202,034	164,812
Parent Company [Member]
Income:
Cash dividends from subsidiaries	[1]	96,500	87,500	84,500
Excess of earnings over dividends of subsidiaries	[1]	140,441	122,997	86,956
Other		279	8,368	7,937
Total interest income		237,220	218,865	179,393
Expenses:
Salaries and employee benefits		7,374	13,795	11,963
Other operating expenses		5,262	5,599	4,756
Total expense		12,636	19,394	16,719
EARNINGS BEFORE INCOME TAXES		224,584	199,471	162,674
Income tax benefit		2,978	2,563	2,138
NET EARNINGS		$ 227,562	$ 202,034	$ 164,812

[1] Eliminates in consolidation