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Allowance for Credit Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	$ 12,883	$ 8,238
Past due	35,644	38,258
Loans, current	7,351,893	7,503,496
Total loans	7,387,537	7,541,754
30 to 59 Days
Financing receivable recorded investment
Past due	20,401	9,307
60 to 89 Days
Financing receivable recorded investment
Past due	1,534	3,606
90 Days or Greater
Financing receivable recorded investment
Past due	13,709	25,345
Commercial, financial and agricultural
Financing receivable recorded investment
Total loans	4,671,168	4,516,288
Commercial, financial and agricultural | Domestic | Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	1,646	318
Past due	4,103	3,603
Loans, current	1,703,321	1,782,333
Total loans	1,707,424	1,785,936
Commercial, financial and agricultural | Domestic | Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	2,171	1,931
Commercial, financial and agricultural | Domestic | Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	286	1,109
Commercial, financial and agricultural | Domestic | Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	1,646	563
Commercial, financial and agricultural | Domestic | Commercial Real Estate: Farmland and Commercial
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	4	186
Past due	3,952	2,840
Loans, current	2,594,425	2,286,468
Total loans	2,598,377	2,289,308
Commercial, financial and agricultural | Domestic | Commercial Real Estate: Farmland and Commercial | 30 to 59 Days
Financing receivable recorded investment
Past due	3,763	2,435
Commercial, financial and agricultural | Domestic | Commercial Real Estate: Farmland and Commercial | 60 to 89 Days
Financing receivable recorded investment
Past due	185	219
Commercial, financial and agricultural | Domestic | Commercial Real Estate: Farmland and Commercial | 90 Days or Greater
Financing receivable recorded investment
Past due	4	186
Commercial, financial and agricultural | Domestic | Commercial Real Estate: Multifamily
Financing receivable recorded investment
Past due		126
Loans, current	365,367	440,918
Total loans	365,367	441,044
Commercial, financial and agricultural | Domestic | Commercial Real Estate: Multifamily | 30 to 59 Days
Financing receivable recorded investment
Past due		126
Real estate - construction
Financing receivable recorded investment
Total loans	1,618,493	1,846,757
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	3,557
Past due	14,937	18,500
Loans, current	1,603,556	1,828,257
Total loans	1,618,493	1,846,757
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | 30 to 59 Days
Financing receivable recorded investment
Past due	10,669	1,059
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | 60 to 89 Days
Financing receivable recorded investment
Past due	51	854
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | 90 Days or Greater
Financing receivable recorded investment
Past due	4,217	16,587
Real estate - mortgage
Financing receivable recorded investment
Total loans	916,153	999,144
Real estate - mortgage | Domestic | Residential First Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	6,451	5,890
Past due	9,298	9,490
Loans, current	389,873	395,629
Total loans	399,171	405,119
Real estate - mortgage | Domestic | Residential First Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	1,967	2,399
Real estate - mortgage | Domestic | Residential First Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	749	926
Real estate - mortgage | Domestic | Residential First Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	6,582	6,165
Real estate - mortgage | Domestic | Residential Junior Lien
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	745	1,197
Past due	2,105	2,005
Loans, current	514,877	592,020
Total loans	516,982	594,025
Real estate - mortgage | Domestic | Residential Junior Lien | 30 to 59 Days
Financing receivable recorded investment
Past due	1,141	561
Real estate - mortgage | Domestic | Residential Junior Lien | 60 to 89 Days
Financing receivable recorded investment
Past due	184	247
Real estate - mortgage | Domestic | Residential Junior Lien | 90 Days or Greater
Financing receivable recorded investment
Past due	780	1,197
Consumer
Financing receivable recorded investment
Total loans	40,505	40,595
Consumer | Domestic
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	14	79
Past due	304	468
Loans, current	40,201	40,127
Total loans	40,505	40,595
Consumer | Domestic | 30 to 59 Days
Financing receivable recorded investment
Past due	211	318
Consumer | Domestic | 60 to 89 Days
Financing receivable recorded investment
Past due	79	71
Consumer | Domestic | 90 Days or Greater
Financing receivable recorded investment
Past due	14	79
Foreign
Financing receivable recorded investment
Total loans	141,218	138,970
Foreign | Foreign
Financing receivable recorded investment
Past due 90 days or Greater and Still Accruing	466	568
Past due	945	1,226
Loans, current	140,273	137,744
Total loans	141,218	138,970
Foreign | Foreign | 30 to 59 Days
Financing receivable recorded investment
Past due	479	478
Foreign | Foreign | 60 to 89 Days
Financing receivable recorded investment
Past due		180
Foreign | Foreign | 90 Days or Greater
Financing receivable recorded investment
Past due	$ 466	$ 568

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