Allowance for Credit Losses - Impairment By Loan Class (Details) $ in Thousands	Sep. 30, 2024 USD ($) loan	Dec. 31, 2023 USD ($)
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	$ 100,575	$ 47,061
Loans Individually Evaluated for Impairment, Allowance	11,385	12,291
Loans Collectively Evaluated for Impairment, Recorded Investment	8,486,450	8,011,900
Loans Collectively Evaluated for Impairment, Allowance	$ 144,714	144,778
Commercial real estate: farmland & commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Number of loans downgraded \| loan	1
Commercial real estate: multifamily
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Number of loans downgraded \| loan	2
Commercial, financial and agricultural \| Domestic \| Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	$ 1,282	30,872
Loans Individually Evaluated for Impairment, Allowance	400	7,971
Loans Collectively Evaluated for Impairment, Recorded Investment	1,691,180	1,597,358
Loans Collectively Evaluated for Impairment, Allowance	29,480	27,579
Commercial, financial and agricultural \| Domestic \| Commercial real estate: farmland & commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	50,831	299
Loans Individually Evaluated for Impairment, Allowance	4,825
Loans Collectively Evaluated for Impairment, Recorded Investment	2,860,756	2,793,254
Loans Collectively Evaluated for Impairment, Allowance	39,559	42,703
Commercial, financial and agricultural \| Domestic \| Commercial real estate: multifamily
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	38,246	96
Loans Individually Evaluated for Impairment, Allowance	660
Loans Collectively Evaluated for Impairment, Recorded Investment	280,685	380,743
Loans Collectively Evaluated for Impairment, Allowance	2,872	5,088
Real estate - construction \| Domestic \| Commercial Real Estate: other construction and land development
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	10,027	15,701
Loans Individually Evaluated for Impairment, Allowance	5,500	4,320
Loans Collectively Evaluated for Impairment, Recorded Investment	2,447,117	2,075,921
Loans Collectively Evaluated for Impairment, Allowance	54,522	50,971
Real estate - mortgage \| Domestic \| Residential First Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	48	93
Loans Collectively Evaluated for Impairment, Recorded Investment	514,179	477,940
Loans Collectively Evaluated for Impairment, Allowance	6,022	5,812
Real estate - mortgage \| Domestic \| Residential Junior Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	141
Loans Collectively Evaluated for Impairment, Recorded Investment	468,843	460,868
Loans Collectively Evaluated for Impairment, Allowance	10,582	11,024
Consumer \| Domestic
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Collectively Evaluated for Impairment, Recorded Investment	48,329	45,121
Loans Collectively Evaluated for Impairment, Allowance	292	318
Foreign \| Foreign
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Collectively Evaluated for Impairment, Recorded Investment	175,361	180,695
Loans Collectively Evaluated for Impairment, Allowance	$ 1,385	$ 1,283

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Amount of allowance for credit loss on financing receivable evaluated on collective basis. Excludes financing receivable evaluated on individual basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
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-Topic 310
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-Section 50
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 30
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479391/326-20-30-2

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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