Allowance for Credit Losses - Roll Forward Of the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Allowance for credit losses:
Beginning balance	$ 201,052	$ 195,292	$ 198,578	$ 192,090	$ 192,090
Charge-offs	(6,372)	(6,185)	(7,282)	(12,642)	(19,040)
Recoveries	891	2,284	1,637	4,009
Net (charge-offs) recoveries	(5,481)	(3,901)	(5,645)	(8,633)
Provision for (recovery of) credit losses on loans	4,300	3,000	6,938	10,960
Ending balance	199,871	194,391	199,871	194,391	198,578
Individually evaluated	10,004	13,015	10,004	13,015
Collectively evaluated	189,867	181,376	189,867	181,376
Loans:
Individually evaluated	54,002	75,472	54,002	75,472
Collectively evaluated	12,550,753	11,855,044	12,550,753	11,855,044
Loans, net of unearned income	12,604,755	11,930,516	12,604,755	11,930,516	12,351,230
Nonaccruing loans with no allowance for credit losses	27,188	16,506	27,188	16,506
Commercial, financial, agricultural
Allowance for credit losses:
Beginning balance	45,921	44,678	43,980	44,255	44,255
Charge-offs	(186)	(4,939)	(535)	(5,468)	(8,838)
Recoveries	525	1,274	871	1,999
Net (charge-offs) recoveries	339	(3,665)	336	(3,469)
Provision for (recovery of) credit losses on loans	(1,309)	297	635	550
Ending balance	44,951	41,310	44,951	41,310	43,980
Individually evaluated	8,514	10,773	8,514	10,773
Collectively evaluated	36,437	30,537	36,437	30,537
Loans:
Individually evaluated	14,211	21,418	14,211	21,418
Collectively evaluated	1,833,551	1,707,652	1,833,551	1,707,652
Loans, net of unearned income	1,847,762	1,729,070	1,847,762	1,729,070
Nonaccruing loans with no allowance for credit losses	230	2,021	230	2,021
Real estate – construction:
Allowance for credit losses:
Beginning balance	17,317	19,959	18,612	19,114	19,114
Charge-offs	0	(57)		(57)
Recoveries	0	0		0
Net (charge-offs) recoveries	0	(57)	0	(57)
Provision for (recovery of) credit losses on loans	1,579	(777)	284	68
Ending balance	18,896	19,125	18,896	19,125	18,612
Individually evaluated	0	0	0	0
Collectively evaluated	18,896	19,125	18,896	19,125
Loans:
Individually evaluated	0	0	0	0
Collectively evaluated	1,355,425	1,369,019	1,355,425	1,369,019
Loans, net of unearned income	1,355,425	1,369,019	1,355,425	1,369,019
Nonaccruing loans with no allowance for credit losses	0	0	0	0
Real estate – 1-4 family mortgage:
Allowance for credit losses:
Beginning balance	47,566	45,981	47,283	44,727	44,727
Charge-offs	(208)	(212)	(290)	(215)	(417)
Recoveries	25	170	73	194
Net (charge-offs) recoveries	(183)	(42)	(217)	(21)
Provision for (recovery of) credit losses on loans	38	495	355	1,728
Ending balance	47,421	46,434	47,421	46,434	47,283
Individually evaluated	0	703	0	703
Collectively evaluated	47,421	45,731	47,421	45,731
Loans:
Individually evaluated	6,942	13,545	6,942	13,545
Collectively evaluated	3,428,876	3,335,109	3,428,876	3,335,109
Loans, net of unearned income	3,435,818	3,348,654	3,435,818	3,348,654
Nonaccruing loans with no allowance for credit losses	6,318	10,516	6,318	10,516
Real estate – commercial mortgage:
Allowance for credit losses:
Beginning balance	78,725	72,770	77,020	71,798	71,798
Charge-offs	(5,727)	(397)	(5,727)	(5,512)	(5,568)
Recoveries	99	278	105	489
Net (charge-offs) recoveries	(5,628)	(119)	(5,622)	(5,023)
Provision for (recovery of) credit losses on loans	4,028	3,016	5,727	8,892
Ending balance	77,125	75,667	77,125	75,667	77,020
Individually evaluated	1,220	1,269	1,220	1,269
Collectively evaluated	75,905	74,398	75,905	74,398
Loans:
Individually evaluated	32,579	40,239	32,579	40,239
Collectively evaluated	5,733,899	5,212,240	5,733,899	5,212,240
Loans, net of unearned income	5,766,478	5,252,479	5,766,478	5,252,479
Nonaccruing loans with no allowance for credit losses	20,640	3,969	20,640	3,969
Lease financing
Allowance for credit losses:
Beginning balance	2,554	2,437	2,515	2,463	2,463
Charge-offs	0	0		0	(1,524)
Recoveries	10	6	18	11
Net (charge-offs) recoveries	10	6	18	11
Provision for (recovery of) credit losses on loans	(49)	37	(18)	6
Ending balance	2,515	2,480	2,515	2,480	2,515
Individually evaluated	0	0	0	0
Collectively evaluated	2,515	2,480	2,515	2,480
Loans:
Individually evaluated	0	0	0	0
Collectively evaluated	102,996	122,370	102,996	122,370
Loans, net of unearned income	102,996	122,370	102,996	122,370
Nonaccruing loans with no allowance for credit losses	0	0	0	0
Installment Loans to Individuals
Allowance for credit losses:
Beginning balance	8,969	9,467	9,168	9,733	9,733
Charge-offs	(251)	(580)	(730)	(1,390)	(2,636)
Recoveries	232	556	570	1,316
Net (charge-offs) recoveries	(19)	(24)	(160)	(74)
Provision for (recovery of) credit losses on loans	13	(68)	(45)	(284)
Ending balance	8,963	9,375	8,963	9,375	9,168
Individually evaluated	270	270	270	270
Collectively evaluated	8,693	9,105	8,693	9,105
Loans:
Individually evaluated	270	270	270	270
Collectively evaluated	96,006	108,654	96,006	108,654
Loans, net of unearned income	96,276	108,924	96,276	108,924
Nonaccruing loans with no allowance for credit losses	$ 0	$ 0	$ 0	0
Cumulative Effect, Period Of Adoption, Adjustment
Allowance for credit losses:
Beginning balance				(26)	(26)
Cumulative Effect, Period Of Adoption, Adjustment | Commercial, financial, agricultural
Allowance for credit losses:
Beginning balance				(26)	(26)
Cumulative Effect, Period Of Adoption, Adjustment | Real estate – construction:
Allowance for credit losses:
Beginning balance				0	0
Cumulative Effect, Period Of Adoption, Adjustment | Real estate – 1-4 family mortgage:
Allowance for credit losses:
Beginning balance				0	0
Cumulative Effect, Period Of Adoption, Adjustment | Real estate – commercial mortgage:
Allowance for credit losses:
Beginning balance				0	0
Cumulative Effect, Period Of Adoption, Adjustment | Lease financing
Allowance for credit losses:
Beginning balance				0	0
Cumulative Effect, Period Of Adoption, Adjustment | Installment Loans to Individuals
Allowance for credit losses:
Beginning balance				$ 0	$ 0