Consolidated Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net earnings	$ 175,807,000	$ 172,225,000
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	9,589,000	9,746,000
Provision for Credit losses	13,353,000	(3,203,000)
Securities premium amortization, net	55,355,000	48,333,000
Discount accretion on purchased loans	(1,119,000)	(1,771,000)
Gain on sale of securities and other assets, net	(3,986,000)	(1,110,000)
Change in loans held-for-sale	17,967,000	34,562,000
Change in other assets	13,508,000	6,308,000
Change in other liabilities	(26,068,000)	780,000
Total adjustments	78,599,000	93,645,000
Net cash provided by operating activities	254,406,000	265,870,000
Activity in available-for-sale securities:
Sales	205,444,000	10,631,000
Maturities	2,773,665,000	8,270,218,000
Purchases	(3,131,413,000)	(9,972,985,000)
Net increase in loans held-for-investment	(862,636,000)	(110,404,000)
Purchases of bank premises and equipment	(11,970,000)	(14,282,000)
Proceeds from sale of bank premises and equipment and other assets	1,186,000	785,000
Net cash used in investing activities	(1,025,724,000)	(1,816,037,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits	420,562,000	591,708,000
Net increase in interest-bearing deposits	155,068,000	625,592,000
Net increase in borrowings	103,429,000	218,586,000
Common stock transactions:
Proceeds from stock option exercises	5,974,000	4,673,000
Dividends paid	(67,072,000)	(58,334,000)
Repuchase of stock	(9,449,000)	0
Net cash provided by financing activities	608,512,000	1,382,225,000
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(162,806,000)	(167,942,000)
CASH AND CASH EQUIVALENTS, beginning of period	528,588,000	729,084,000
CASH AND CASH EQUIVALENTS, end of period	365,782,000	561,142,000
SUPPLEMENTAL INFORMATION AND NONCASH TRANSACTIONS:
Interest paid	14,067,000	4,938,000
Federal income taxes paid	33,050,000	31,073,000
Transfer of loans to other real estate	0	296,000
Investment securities purchased but not settled	0	174,236,000
Restricted stock grant (forfeiture)	$ 1,681,000	$ (165,000)