Allowance for Credit Losses - Changes in the Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for loan losses:
Beginning balance	$ 176,144	$ 52,162
Charge-offs	(18,874)	(16,105)
Recoveries	8,601	12,253
Net charge-offs	(10,273)	(3,852)
Provision (recoveries) of credit losses on loans	(1,700)	85,350	$ 7,050
Ending balance	164,171	$ 176,144	52,162
Accounting Standards Update [Extensible List]		Accounting Standards Update 2016-13 [Member]
Individually evaluated	12,463	$ 14,190	2,012
Collectively evaluated	151,708	161,954	48,179
Loans:
Individually evaluated	33,449	44,350
Collectively evaluated	9,987,465	10,889,297
Gross loans	10,020,914	10,933,647
Nonaccruing loans with no allowance for credit losses	$ 8,018	8,977
Financing Receivable, Credit Loss Expense Supportable Period	2 years
Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses:
Purchased with deteriorated credit quality			1,971
Commercial, financial, agricultural
Allowance for loan losses:
Beginning balance	$ 39,031	10,658	8,269
Charge-offs	(7,087)	(3,577)	(2,681)
Recoveries	1,470	1,263	1,428
Net charge-offs	(5,617)	(2,314)	(1,253)
Provision (recoveries) of credit losses on loans	508	19,336	3,642
Ending balance	33,922	39,031	10,658
Individually evaluated	9,239	10,345	1,434
Collectively evaluated	24,683	28,686	8,932
Purchased with deteriorated credit quality			292
Loans:
Individually evaluated	12,776	16,091
Collectively evaluated	1,410,494	2,520,893
Gross loans	1,423,270	2,536,984
Nonaccruing loans with no allowance for credit losses	397	541
Real estate – construction:
Allowance for loan losses:
Beginning balance	16,047	5,029	4,755
Charge-offs	(52)	(716)	0
Recoveries	13	31	21
Net charge-offs	(39)	(685)	21
Provision (recoveries) of credit losses on loans	411	8,198	253
Ending balance	16,419	16,047	5,029
Individually evaluated	0	497	16
Collectively evaluated	16,419	15,550	5,013
Purchased with deteriorated credit quality			0
Loans:
Individually evaluated	0	497
Collectively evaluated	1,104,896	857,607
Gross loans	1,104,896	858,104
Nonaccruing loans with no allowance for credit losses	0	0
Real Estate - 1-4 Family Mortgage
Allowance for loan losses:
Beginning balance	32,165	9,814	10,139
Charge-offs	(1,164)	(1,167)	(1,602)
Recoveries	1,498	838	712
Net charge-offs	334	(329)	(890)
Provision (recoveries) of credit losses on loans	(143)	8,366	565
Ending balance	32,356	32,165	9,814
Individually evaluated	216	300	160
Collectively evaluated	32,140	31,865	9,363
Purchased with deteriorated credit quality			291
Loans:
Individually evaluated	5,360	5,379
Collectively evaluated	2,718,886	2,692,929
Gross loans	2,724,246	2,698,308
Nonaccruing loans with no allowance for credit losses	2,329	4,054
Real estate – commercial mortgage:
Allowance for loan losses:
Beginning balance	76,127	24,990	24,492
Charge-offs	(5,184)	(2,642)	(1,490)
Recoveries	541	2,478	689
Net charge-offs	(4,643)	(164)	(801)
Provision (recoveries) of credit losses on loans	(2,544)	47,008	1,299
Ending balance	68,940	76,127	24,990
Individually evaluated	2,401	2,444	396
Collectively evaluated	66,539	73,683	23,208
Purchased with deteriorated credit quality			1,386
Loans:
Individually evaluated	14,623	21,764
Collectively evaluated	4,534,414	4,533,088
Gross loans	4,549,037	4,554,852
Nonaccruing loans with no allowance for credit losses	5,270	4,382
Lease financing
Allowance for loan losses:
Beginning balance	1,624	910	1,371
Charge-offs	(13)	(168)	(7,705)
Recoveries	49	11	6,714
Net charge-offs	36	(157)	(991)
Provision (recoveries) of credit losses on loans	(174)	350	1,291
Ending balance	1,486	1,624	910
Individually evaluated	0	0
Collectively evaluated	1,486	1,624
Loans:
Individually evaluated	0	0
Collectively evaluated	76,125	75,862
Gross loans	76,125	75,862
Nonaccruing loans with no allowance for credit losses	0	0
Installment and Other
Allowance for loan losses:
Beginning balance		1,671
Ending balance			1,671
Individually evaluated			6
Collectively evaluated			1,663
Purchased with deteriorated credit quality			2
Installment loans to individuals
Allowance for loan losses:
Beginning balance	11,150	761	49,026
Charge-offs	(5,374)	(7,835)	(13,478)
Recoveries	5,030	7,632	9,564
Net charge-offs	(344)	(203)	(3,914)
Provision (recoveries) of credit losses on loans	242	2,092	7,050
Ending balance	11,048	11,150	761
Individually evaluated	607	604
Collectively evaluated	10,441	10,546
Loans:
Individually evaluated	690	619
Collectively evaluated	142,650	208,918
Gross loans	143,340	209,537
Nonaccruing loans with no allowance for credit losses	$ 22	0
Impact of the adoption of ASC 326
Allowance for loan losses:
Beginning balance		42,484
Ending balance			42,484
Impact of the adoption of ASC 326 | Commercial, financial, agricultural
Allowance for loan losses:
Beginning balance		11,351
Ending balance			11,351
Impact of the adoption of ASC 326 | Real estate – construction:
Allowance for loan losses:
Beginning balance		3,505
Ending balance			3,505
Impact of the adoption of ASC 326 | Real Estate - 1-4 Family Mortgage
Allowance for loan losses:
Beginning balance		14,314
Ending balance			14,314
Impact of the adoption of ASC 326 | Real estate – commercial mortgage:
Allowance for loan losses:
Beginning balance		4,293
Ending balance			4,293
Impact of the adoption of ASC 326 | Lease financing
Allowance for loan losses:
Beginning balance		521
Ending balance			521
Impact of the adoption of ASC 326 | Installment loans to individuals
Allowance for loan losses:
Beginning balance		$ 8,500
Ending balance			$ 8,500