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Loans - Amortized Cost of Nonaccrual Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Nonaccrual With No Allowance For Credit Loss [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | $ 3,764 | $ 2,392
Nonaccrual With No Allowance For Credit Loss [Member] | Consumer Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 2,561 | 1,637
Nonaccrual With No Allowance For Credit Loss [Member] | Agricultural Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 463 | 130
Nonaccrual With No Allowance For Credit Loss [Member] | Agricultural [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 90 | 90
Nonaccrual With No Allowance For Credit Loss [Member] | Commercial Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 552 | 360
Nonaccrual With No Allowance For Credit Loss [Member] | Commercial & Industrial [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 28 | 57
Nonaccrual With No Allowance For Credit Loss [Member] | Consumer [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 70 | 118
Nonaccrual [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 4,492 | 3,124
Nonaccrual [Member] | Consumer Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 3,289 | 2,369
Nonaccrual [Member] | Agricultural Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 463 | 130
Nonaccrual [Member] | Agricultural [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 90 | 90
Nonaccrual [Member] | Commercial Real Estate [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 552 | 360
Nonaccrual [Member] | Commercial & Industrial [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | 28 | 57
Nonaccrual [Member] | Consumer [Member] |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Investment in nonaccrual loans | $ 70 | $ 118

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