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Loans (Tier Risk Rating System) - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2023
Nonaccrual [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Interest income on nonaccrual loans | $ 74 | $ 210
Nonaccrual [Member] | Agricultural Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Combined increase in nonaccrual loans due to two borrower relationships |  | 15,600
Nonaccrual [Member] | Agricultural [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Combined increase in nonaccrual loans due to two borrower relationships |  | $ 4,500
Minimum [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Repayment period of loan with a reasonable reduction of principal balance |  | 2 years

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