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Loans and Allowance for Loan Losses - Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2021 USD ($) | Sep. 30, 2021 Loan | Sep. 30, 2021 DebtSecurityNumber | Dec. 31, 2020 USD ($) | Dec. 31, 2020 Loan | Dec. 31, 2020 DebtSecurityNumber
Number of loans |  | 2 | 7 |  | 0 | 5
Pre- Modification Outstanding Principal Balance | $ 903 |  |  | $ 282 |  |
Post- Modification Principal Balance | 663 |  |  | 51 |  |
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] |  |  |  |  |  |
Number of loans | DebtSecurityNumber |  |  | 1 |  |  | 1
Pre- Modification Outstanding Principal Balance | 107 |  |  | 107 |  |
Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] |  |  |  |  |  |
Number of loans | DebtSecurityNumber |  |  | 2 |  |  | 2
Pre- Modification Outstanding Principal Balance | 59 |  |  | 59 |  |
Post- Modification Principal Balance | 12 |  |  | 12 |  |
Real Estate [Member] | Secured By Non-farm Non residential Properties [Member] |  |  |  |  |  |
Number of loans | DebtSecurityNumber |  |  | 2 |  |  |
Pre- Modification Outstanding Principal Balance | 621 |  |  |  |  |
Post- Modification Principal Balance | 618 |  |  |  |  |
Commercial and Industrial Loans [Member] |  |  |  |  |  |
Number of loans | DebtSecurityNumber |  |  | 2 |  |  | 2
Pre- Modification Outstanding Principal Balance | 116 |  |  | 116 |  |
Post- Modification Principal Balance | $ 33 |  |  | $ 39 |  |

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