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Allowance for Credit Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Loan loss allowances, financing receivable past due |  |  |
Non-accrual loans, total | $ 47,170,000 | $ 51,648,000 | $ 1,921,000
Reduced interest income on non-accrual loans | 6,614,000 | 116,000 | $ 169,000
Commercial, financial and agricultural | Domestic | Commercial. |  |  |
Loan loss allowances, financing receivable past due |  |  |
Non-accrual loans, total | 30,872,000 | 30,747,000 |
Commercial, financial and agricultural | Domestic | Commercial real estate: farmland & commercial |  |  |
Loan loss allowances, financing receivable past due |  |  |
Non-accrual loans, total | 299,000 | 94,000 |
Commercial, financial and agricultural | Domestic | Commercial real estate: multifamily |  |  |
Loan loss allowances, financing receivable past due |  |  |
Non-accrual loans, total | 96,000 | 117,000 |
Obligations of states and political subdivisions | Domestic | Commercial Real Estate: other construction and land development |  |  |
Loan loss allowances, financing receivable past due |  |  |
Non-accrual loans, total | 15,701,000 | 20,483,000 |
Real estate - mortgage | Domestic | Residential: first lien |  |  |
Loan loss allowances, financing receivable past due |  |  |
Non-accrual loans, total | $ 202,000 | $ 207,000 |

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