Allowance for Credit Losses - Roll Forward Of the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Allowance for loan losses:
Beginning balance	$ 166,468	$ 173,106	$ 164,171	$ 176,144
Charge-offs	(3,958)	(2,854)	(7,015)	(8,224)
Recoveries	1,621	2,102	3,827	4,434
Net (charge-offs) recoveries	(2,337)	(752)	(3,188)	(3,790)
Provision for credit losses on loans	2,000	0	3,500	0
Ending balance	166,131	172,354	166,131	172,354
Individually evaluated	6,896	14,168	6,896	14,168
Collectively evaluated	159,235	158,186	159,235	158,186
Loans:
Individually evaluated	25,947	40,872	25,947	40,872
Collectively evaluated	10,577,797	10,108,370	10,577,797	10,108,370
Loans, net of unearned income	10,603,744	10,149,242	10,603,744	10,149,242	$ 10,020,914
Nonaccruing loans with no allowance for credit losses	7,935	10,630	7,935	10,630
Commercial, financial, agricultural
Allowance for loan losses:
Beginning balance	33,606	37,592	33,922	39,031
Charge-offs	(2,239)	(1,184)	(4,341)	(4,682)
Recoveries	431	233	1,567	522
Net (charge-offs) recoveries	(1,808)	(951)	(2,774)	(4,160)
Provision for credit losses on loans	(1,605)	353	(2,603)	2,123
Ending balance	30,193	36,994	30,193	36,994
Individually evaluated	4,567	9,121	4,567	9,121
Collectively evaluated	25,626	27,873	25,626	27,873
Loans:
Individually evaluated	9,534	14,409	9,534	14,409
Collectively evaluated	1,487,738	1,620,224	1,487,738	1,620,224
Loans, net of unearned income	1,497,272	1,634,633	1,497,272	1,634,633
Nonaccruing loans with no allowance for credit losses	849	2,826	849	2,826
Real estate – construction:
Allowance for loan losses:
Beginning balance	18,411	14,977	16,419	16,047
Charge-offs	0	0	0	(52)
Recoveries	0	0	0	13
Net (charge-offs) recoveries	0	0	0	(39)
Provision for credit losses on loans	(1,121)	752	871	(279)
Ending balance	17,290	15,729	17,290	15,729
Individually evaluated	0	0	0	0
Collectively evaluated	17,290	15,729	17,290	15,729
Loans:
Individually evaluated	0	0	0	0
Collectively evaluated	1,126,363	1,051,359	1,126,363	1,051,359
Loans, net of unearned income	1,126,363	1,051,359	1,126,363	1,051,359
Nonaccruing loans with no allowance for credit losses	0	0	0	0
Real estate – 1-4 family mortgage:
Allowance for loan losses:
Beginning balance	36,848	31,694	32,356	32,165
Charge-offs	(161)	(152)	(324)	(253)
Recoveries	169	401	347	662
Net (charge-offs) recoveries	8	249	23	409
Provision for credit losses on loans	5,054	(640)	9,531	(1,271)
Ending balance	41,910	31,303	41,910	31,303
Individually evaluated	85	228	85	228
Collectively evaluated	41,825	31,075	41,825	31,075
Loans:
Individually evaluated	4,127	5,017	4,127	5,017
Collectively evaluated	3,025,956	2,697,074	3,025,956	2,697,074
Loans, net of unearned income	3,030,083	2,702,091	3,030,083	2,702,091
Nonaccruing loans with no allowance for credit losses	3,594	2,841	3,594	2,841
Real estate – commercial mortgage:
Allowance for loan losses:
Beginning balance	65,231	76,225	68,940	76,127
Charge-offs	(708)	(171)	(714)	(232)
Recoveries	192	143	347	314
Net (charge-offs) recoveries	(516)	(28)	(367)	82
Provision for credit losses on loans	(342)	(1,304)	(4,200)	(1,316)
Ending balance	64,373	74,893	64,373	74,893
Individually evaluated	1,674	4,207	1,674	4,207
Collectively evaluated	62,699	70,686	62,699	70,686
Loans:
Individually evaluated	11,716	20,810	11,716	20,810
Collectively evaluated	4,705,797	4,509,359	4,705,797	4,509,359
Loans, net of unearned income	4,717,513	4,530,169	4,717,513	4,530,169
Nonaccruing loans with no allowance for credit losses	3,492	4,953	3,492	4,953
Lease financing
Allowance for loan losses:
Beginning balance	1,582	1,546	1,486	1,624
Charge-offs	0	0	(7)	0
Recoveries	11	14	23	25
Net (charge-offs) recoveries	11	14	16	25
Provision for credit losses on loans	209	(49)	300	(138)
Ending balance	1,802	1,511	1,802	1,511
Individually evaluated	0	0	0	0
Collectively evaluated	1,802	1,511	1,802	1,511
Loans:
Individually evaluated	0	0	0	0
Collectively evaluated	101,350	74,003	101,350	74,003
Loans, net of unearned income	101,350	74,003	101,350	74,003
Nonaccruing loans with no allowance for credit losses	0	0	0	0
Installment Loans to Individuals
Allowance for loan losses:
Beginning balance	10,790	11,072	11,048	11,150
Charge-offs	(850)	(1,347)	(1,629)	(3,005)
Recoveries	818	1,311	1,543	2,898
Net (charge-offs) recoveries	(32)	(36)	(86)	(107)
Provision for credit losses on loans	(195)	888	(399)	881
Ending balance	10,563	11,924	10,563	11,924
Individually evaluated	570	612	570	612
Collectively evaluated	9,993	11,312	9,993	11,312
Loans:
Individually evaluated	570	636	570	636
Collectively evaluated	130,593	156,351	130,593	156,351
Loans, net of unearned income	131,163	156,987	131,163	156,987
Nonaccruing loans with no allowance for credit losses	$ 0	$ 10	0	$ 10
Cumulative Effect, Period Of Adoption, Adjustment
Allowance for loan losses:
Beginning balance			1,648
Cumulative Effect, Period Of Adoption, Adjustment | Commercial, financial, agricultural
Allowance for loan losses:
Beginning balance			1,648
Cumulative Effect, Period Of Adoption, Adjustment | Real estate – construction:
Allowance for loan losses:
Beginning balance			0
Cumulative Effect, Period Of Adoption, Adjustment | Real estate – 1-4 family mortgage:
Allowance for loan losses:
Beginning balance			0
Cumulative Effect, Period Of Adoption, Adjustment | Real estate – commercial mortgage:
Allowance for loan losses:
Beginning balance			0
Cumulative Effect, Period Of Adoption, Adjustment | Lease financing
Allowance for loan losses:
Beginning balance			0
Cumulative Effect, Period Of Adoption, Adjustment | Installment Loans to Individuals
Allowance for loan losses:
Beginning balance			$ 0