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Loans (Impaired Loans) - Additional Information (Detail) | 1 Months Ended | 3 Months Ended |
--- | --- | --- | ---
May 31, 2020 Loan | Mar. 31, 2021 USD ($) Contract Loan | Mar. 31, 2020 USD ($) Contract Loan | Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Additional funds available to be advanced in connection with impaired loans |  | $ 150,000 |  |
Impaired loans classified as troubled debt restructured |  | $ 5,800,000 | $ 1,900,000 | $ 6,500,000
Number of contracts modified | Loan |  | 0 |  |
TDR impaired loans paid off | Loan | 1 | 0 | 0 |
TDR loans, subsequently defaulted during the period |  | 0 | 0 |
TDR impaired loans charged off | Loan |  |  | 0 |
Maximum time for re-evaluation (in months) |  | 12 months |  |
Re-evaluation period for real estate |  | 2 years |  |
Unsecured consumer loans, credit card credits and overdraft lines of credit reach |  | 90 days |  |
Delinquent period for charging down consumer loans |  | 90 days |  |
Delinquent period for charging down commercial and agricultural credits |  | 120 days |  |
Foreclosed residential real estate property |  | $ 148,000 |  | 71,000
Maximum [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Litigation and any deficiency charged off period |  | 150 days |  |
Commercial and Industrial [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
TDR impaired loans paid off | Loan |  | 3 |  |
TDR impaired loans charged off amount |  | $ 809,000 |  |
Consumer Real Estate [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Number of contracts modified | Contract |  |  | 2 |
Foreclosed residential real estate property |  | 148,000 | $ 50,000 | 71,000
Residential real estate properties foreclosure proceedings |  | $ 796,000 | $ 292,000 | $ 910,000
Principal Forgiveness [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Number of contracts modified | Contract |  | 0 |  |
Payment Changes from Monthly Payment to Principal and Interest at Maturity [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Number of contracts modified | Contract |  |  | 2 |
Loan maturity date |  | Jun. 19, 2020 |  |

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