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Allowance for Credit Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | $ 2,895 | $ 19,822
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 1,055 | 1,189
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 422 | 439
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 127 | 134
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 892 | 17,496
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 361 | 526
Real estate - mortgage | Domestic | Residential Junior Lien |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | $ 38 | $ 38

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