Allowance for Credit Losses - Roll Forward Of the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Allowance for credit losses:
Beginning balance	$ 195,292	$ 166,468	$ 192,090	$ 164,171
Charge-offs	(6,185)	(3,958)	(12,642)	(7,015)
Recoveries	2,284	1,621	4,009	3,827
Net (charge-offs) recoveries	(3,901)	(2,337)	(8,633)	(3,188)
Provision for (recovery of) credit losses on loans	3,000	2,000	10,960	3,500
Ending balance	194,391	166,131	194,391	166,131
Individually evaluated	13,015	6,896	13,015	6,896
Collectively evaluated	181,376	159,235	181,376	159,235
Loans:
Individually evaluated	75,472	25,947	75,472	25,947
Collectively evaluated	11,855,044	10,577,797	11,855,044	10,577,797
Loans, net of unearned income	11,930,516	10,603,744	11,930,516	10,603,744	$ 11,578,304
Nonaccruing loans with no allowance for credit losses	16,506	7,935	16,506	7,935
Commercial, financial, agricultural
Allowance for credit losses:
Beginning balance	44,678	33,606	44,255	33,922
Charge-offs	(4,939)	(2,239)	(5,468)	(4,341)
Recoveries	1,274	431	1,999	1,567
Net (charge-offs) recoveries	(3,665)	(1,808)	(3,469)	(2,774)
Provision for (recovery of) credit losses on loans	297	(1,605)	550	(2,603)
Ending balance	41,310	30,193	41,310	30,193
Individually evaluated	10,773	4,567	10,773	4,567
Collectively evaluated	30,537	25,626	30,537	25,626
Loans:
Individually evaluated	21,418	9,534	21,418	9,534
Collectively evaluated	1,707,652	1,487,738	1,707,652	1,487,738
Loans, net of unearned income	1,729,070	1,497,272	1,729,070	1,497,272
Nonaccruing loans with no allowance for credit losses	2,021	849	2,021	849
Real estate – construction:
Allowance for credit losses:
Beginning balance	19,959	18,411	19,114	16,419
Charge-offs	(57)	0	(57)	0
Recoveries	0	0	0	0
Net (charge-offs) recoveries	(57)	0	(57)	0
Provision for (recovery of) credit losses on loans	(777)	(1,121)	68	871
Ending balance	19,125	17,290	19,125	17,290
Individually evaluated	0	0	0	0
Collectively evaluated	19,125	17,290	19,125	17,290
Loans:
Individually evaluated	0	0	0	0
Collectively evaluated	1,369,019	1,126,363	1,369,019	1,126,363
Loans, net of unearned income	1,369,019	1,126,363	1,369,019	1,126,363
Nonaccruing loans with no allowance for credit losses	0	0	0	0
Real estate – 1-4 family mortgage:
Allowance for credit losses:
Beginning balance	45,981	36,848	44,727	32,356
Charge-offs	(212)	(161)	(215)	(324)
Recoveries	170	169	194	347
Net (charge-offs) recoveries	(42)	8	(21)	23
Provision for (recovery of) credit losses on loans	495	5,054	1,728	9,531
Ending balance	46,434	41,910	46,434	41,910
Individually evaluated	703	85	703	85
Collectively evaluated	45,731	41,825	45,731	41,825
Loans:
Individually evaluated	13,545	4,127	13,545	4,127
Collectively evaluated	3,335,109	3,025,956	3,335,109	3,025,956
Loans, net of unearned income	3,348,654	3,030,083	3,348,654	3,030,083
Nonaccruing loans with no allowance for credit losses	10,516	3,594	10,516	3,594
Real estate – commercial mortgage:
Allowance for credit losses:
Beginning balance	72,770	65,231	71,798	68,940
Charge-offs	(397)	(708)	(5,512)	(714)
Recoveries	278	192	489	347
Net (charge-offs) recoveries	(119)	(516)	(5,023)	(367)
Provision for (recovery of) credit losses on loans	3,016	(342)	8,892	(4,200)
Ending balance	75,667	64,373	75,667	64,373
Individually evaluated	1,269	1,674	1,269	1,674
Collectively evaluated	74,398	62,699	74,398	62,699
Loans:
Individually evaluated	40,239	11,716	40,239	11,716
Collectively evaluated	5,212,240	4,705,797	5,212,240	4,705,797
Loans, net of unearned income	5,252,479	4,717,513	5,252,479	4,717,513
Nonaccruing loans with no allowance for credit losses	3,969	3,492	3,969	3,492
Lease financing
Allowance for credit losses:
Beginning balance	2,437	1,582	2,463	1,486
Charge-offs	0	0	0	(7)
Recoveries	6	11	11	23
Net (charge-offs) recoveries	6	11	11	16
Provision for (recovery of) credit losses on loans	37	209	6	300
Ending balance	2,480	1,802	2,480	1,802
Individually evaluated	0	0	0	0
Collectively evaluated	2,480	1,802	2,480	1,802
Loans:
Individually evaluated	0	0	0	0
Collectively evaluated	122,370	101,350	122,370	101,350
Loans, net of unearned income	122,370	101,350	122,370	101,350
Nonaccruing loans with no allowance for credit losses	0	0	0	0
Installment Loans to Individuals
Allowance for credit losses:
Beginning balance	9,467	10,790	9,733	11,048
Charge-offs	(580)	(850)	(1,390)	(1,629)
Recoveries	556	818	1,316	1,543
Net (charge-offs) recoveries	(24)	(32)	(74)	(86)
Provision for (recovery of) credit losses on loans	(68)	(195)	(284)	(399)
Ending balance	9,375	10,563	9,375	10,563
Individually evaluated	270	570	270	570
Collectively evaluated	9,105	9,993	9,105	9,993
Loans:
Individually evaluated	270	570	270	570
Collectively evaluated	108,654	130,593	108,654	130,593
Loans, net of unearned income	108,924	131,163	108,924	131,163
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)	1,648
Cumulative Effect, Period Of Adoption, Adjustment | Commercial, financial, agricultural
Allowance for credit losses:
Beginning balance			(26)	1,648
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