Fair Values of Financial Instruments - Schedule of Estimated Fair Values of Recognized Financial Instruments Carried at Amortized Cost (Detail) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Financial assets
Securities held-to-maturity	$ 156,463	$ 161,052
Loans held for sale	546	213
Carrying Value [Member]
Financial assets
Securities held-to-maturity	179,155	183,145
Loans held for sale	546	213
Net loans	839,771	817,308
Financial liabilities
Deposits	1,101,821	1,127,915
Other borrowings	892	917
Carrying Value [Member] \| Mortgage Servicing Rights [Member]
Financial assets
Mortgage servicing rights	624	625
Fair Value [Member]
Financial assets
Securities held-to-maturity	156,463	161,052
Loans held for sale	555	217
Net loans	808,403	784,544
Financial liabilities
Deposits	1,103,587	1,129,512
Other borrowings	810	835
Fair Value [Member] \| Mortgage Servicing Rights [Member]
Financial assets
Mortgage servicing rights	624	625
Fair Value [Member] \| Level I [Member]
Financial assets
Loans held for sale	555	217
Financial liabilities
Deposits	831,935	865,010
Fair Value [Member] \| Level II [Member]
Financial assets
Securities held-to-maturity	156,463	161,052
Fair Value [Member] \| Level III [Member]
Financial assets
Net loans	808,403	784,544
Financial liabilities
Deposits	271,652	264,502
Other borrowings	810	835
Fair Value [Member] \| Level III [Member] \| Mortgage Servicing Rights [Member]
Financial assets
Mortgage servicing rights	$ 624	$ 625

Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.

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