Allowance for Credit Losses - Roll Forward Of the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Allowance for credit losses:
Beginning balance	$ 192,090	$ 164,171
Charge-offs	(6,457)	(3,057)
Recoveries	1,725	2,206
Net (charge-offs) recoveries	(4,732)	(851)
Provision for (recovery of) credit losses on loans	7,960	1,500
Ending balance	195,292	166,468
Individually evaluated	16,809	12,851
Collectively evaluated	178,483	153,617
Loans:
Individually evaluated	48,923	33,581
Collectively evaluated	11,717,502	10,279,878
Loans, net of unearned income	11,766,425	10,313,459	$ 11,578,304
Nonaccruing loans with no allowance for credit losses	15,994	8,349
Commercial, financial, agricultural
Allowance for credit losses:
Beginning balance	44,255	33,922
Charge-offs	(529)	(2,102)
Recoveries	725	1,136
Net (charge-offs) recoveries	196	(966)
Provision for (recovery of) credit losses on loans	253	(998)
Ending balance	44,678	33,606
Individually evaluated	14,162	9,225
Collectively evaluated	30,516	24,381
Loans:
Individually evaluated	24,985	13,070
Collectively evaluated	1,715,793	1,432,537
Loans, net of unearned income	1,740,778	1,445,607
Nonaccruing loans with no allowance for credit losses	768	435
Real estate – construction:
Allowance for credit losses:
Beginning balance	19,114	16,419
Charge-offs	0	0
Recoveries	0	0
Net (charge-offs) recoveries	0	0
Provision for (recovery of) credit losses on loans	845	1,992
Ending balance	19,959	18,411
Individually evaluated	35	0
Collectively evaluated	19,924	18,411
Loans:
Individually evaluated	652	0
Collectively evaluated	1,423,700	1,222,052
Loans, net of unearned income	1,424,352	1,222,052
Nonaccruing loans with no allowance for credit losses	0	0
Real estate – 1-4 family mortgage:
Allowance for credit losses:
Beginning balance	44,727	32,356
Charge-offs	(3)	(163)
Recoveries	24	178
Net (charge-offs) recoveries	21	15
Provision for (recovery of) credit losses on loans	1,233	4,477
Ending balance	45,981	36,848
Individually evaluated	608	396
Collectively evaluated	45,373	36,452
Loans:
Individually evaluated	12,637	4,477
Collectively evaluated	3,266,343	2,836,502
Loans, net of unearned income	3,278,980	2,840,979
Nonaccruing loans with no allowance for credit losses	9,710	2,614
Real estate – commercial mortgage:
Allowance for credit losses:
Beginning balance	71,798	68,940
Charge-offs	(5,115)	(6)
Recoveries	211	155
Net (charge-offs) recoveries	(4,904)	149
Provision for (recovery of) credit losses on loans	5,876	(3,858)
Ending balance	72,770	65,231
Individually evaluated	1,734	2,660
Collectively evaluated	71,036	62,571
Loans:
Individually evaluated	10,375	15,464
Collectively evaluated	5,075,438	4,562,400
Loans, net of unearned income	5,085,813	4,577,864
Nonaccruing loans with no allowance for credit losses	5,511	5,298
Lease financing
Allowance for credit losses:
Beginning balance	2,463	1,486
Charge-offs	0	(7)
Recoveries	5	12
Net (charge-offs) recoveries	5	5
Provision for (recovery of) credit losses on loans	(31)	91
Ending balance	2,437	1,582
Individually evaluated	0	0
Collectively evaluated	2,437	1,582
Loans:
Individually evaluated	0	0
Collectively evaluated	121,146	89,842
Loans, net of unearned income	121,146	89,842
Nonaccruing loans with no allowance for credit losses	0	0
Installment Loans to Individuals
Allowance for credit losses:
Beginning balance	9,733	11,048
Charge-offs	(810)	(779)
Recoveries	760	725
Net (charge-offs) recoveries	(50)	(54)
Provision for (recovery of) credit losses on loans	(216)	(204)
Ending balance	9,467	10,790
Individually evaluated	270	570
Collectively evaluated	9,197	10,220
Loans:
Individually evaluated	274	570
Collectively evaluated	115,082	136,545
Loans, net of unearned income	115,356	137,115
Nonaccruing loans with no allowance for credit losses	5	2
Cumulative Effect, Period Of Adoption, Adjustment
Allowance for credit losses:
Beginning balance	(26)
Ending balance		1,648
Cumulative Effect, Period Of Adoption, Adjustment \| Commercial, financial, agricultural
Allowance for credit losses:
Beginning balance	(26)
Ending balance		1,648
Cumulative Effect, Period Of Adoption, Adjustment \| Real estate – construction:
Allowance for credit losses:
Beginning balance	0
Ending balance		0
Cumulative Effect, Period Of Adoption, Adjustment \| Real estate – 1-4 family mortgage:
Allowance for credit losses:
Beginning balance	0
Ending balance		0
Cumulative Effect, Period Of Adoption, Adjustment \| Real estate – commercial mortgage:
Allowance for credit losses:
Beginning balance	0
Ending balance		0
Cumulative Effect, Period Of Adoption, Adjustment \| Lease financing
Allowance for credit losses:
Beginning balance	0
Ending balance		0
Cumulative Effect, Period Of Adoption, Adjustment \| Installment Loans to Individuals
Allowance for credit losses:
Beginning balance	$ 0
Ending balance		$ 0

Amount, after recovery, of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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The balance of financing receivables that were collectively evaluated for impairment.

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Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease.

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Amortized cost, before allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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