Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net earnings	$ 227,562,000	$ 202,034,000	$ 164,812,000
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	13,061,000	12,793,000	11,665,000
Provision for credit losses	(1,139,000)	19,517,000	2,965,000
Securities premium amortization, net	68,308,000	41,959,000	25,788,000
Discount accretion on purchased loans	(2,362,000)	(3,780,000)	(1,666,000)
Gain on sale of assets, net	(1,217,000)	(4,001,000)	(1,477,000)
Deferred federal income tax (expense) benefit	3,531,000	(5,249,000)	(29,000)
Change in loans held-for-sale	44,098,000	(53,494,000)	(5,830,000)
Change in other assets	(11,308,000)	(23,233,000)	1,851,000
Change in other liabilities	12,697,000	24,122,000	4,374,000
Total adjustments	125,669,000	8,634,000	37,641,000
Net cash provided by operating activities	353,231,000	210,668,000	202,453,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Net decrease in interest-bearing time deposits in banks			1,458,000
Activity in available-for-sale securities and other investments:
Sales	10,631,000	263,042,000	67,414,000
Maturities	8,495,614,000	6,075,017,000	4,460,703,000
Purchases	(10,887,727,000)	(7,117,151,000)	(4,727,430,000)
Net increase in loans held-for-investment	(211,786,000)	(529,144,000)	(243,524,000)
Purchases of bank premises and equipment	(19,205,000)	(16,450,000)	(8,671,000)
Proceeds from sale of bank premises and equipment and other assets	823,000	1,456,000	2,249,000
Net cash used in investing activities	(2,611,650,000)	(1,262,202,000)	(447,801,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits	797,533,000	679,744,000	(50,979,000)
Net increase in interest-bearing deposits	1,093,138,000	843,142,000	474,396,000
Net increase (decrease) in borrowings	241,059,000	48,737,000	(87,350,000)
Common stock transactions:
Proceeds from stock option exercises	5,905,000	4,717,000	4,294,000
Dividends paid	(79,712,000)	(70,318,000)	(61,056,000)
Repurchase of stock		(8,008,000)
Net cash provided by financing activities	2,057,923,000	1,498,014,000	279,305,000
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(200,496,000)	446,480,000	33,957,000
CASH AND CASH EQUIVALENTS, beginning of year	729,084,000	282,604,000	248,647,000
CASH AND CASH EQUIVALENTS, end of year	$ 528,588,000	729,084,000	$ 282,604,000
TB And T Bacshares Inc [Member]
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash received in acquisition, Net		$ 61,028,000