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Loans - Distribution of Fixed Rate Loans and Variable Rate Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Consumer Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | $ 272,560 | $ 305,062
Distribution of variable rate loans by major loan category, Variable Rate | 249,856 | 215,052
Agricultural Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | 108,445 | 118,808
Distribution of variable rate loans by major loan category, Variable Rate | 113,700 | 97,593
Agricultural [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | 49,321 | 54,099
Distribution of variable rate loans by major loan category, Variable Rate | 130,040 | 97,981
Commercial Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | 863,683 | 934,197
Distribution of variable rate loans by major loan category, Variable Rate | 491,483 | 376,614
Commercial and Industrial [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | 118,175 | 148,542
Distribution of variable rate loans by major loan category, Variable Rate | 177,909 | 126,610
Consumer [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | 60,439 | 62,977
Distribution of variable rate loans by major loan category, Variable Rate | 30 | 32
Other Loan [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Distribution of fixed rate loans by major loan category, Fixed Rate | 14,657 | 15,270
Distribution of variable rate loans by major loan category, Variable Rate | $ 9,429 | $ 9,708

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