Loans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2023 USD ($) Property Industry	Dec. 31, 2022 USD ($) Property
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 701,481,000	$ 626,958,000
Number of properties acquired | Property	0	0
Mortgage loans in process of foreclosure amount	$ 8,000	$ 17,000
Outstanding exposure balance of commercial loans classified under credit risk, minimum amount	500,000
Loans serviced for others including commercial loans	132,000,000	138,000,000
Mortgage Servicing Rights [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage servicing rights	600,000	621,000
Valuation allowance	0	0
Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential mortgage loans sold with servicing retained	$ 124,000,000	130,000,000
Credit Concentrations Risk [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of industries for credit concentrations | Industry	3
Credit Concentrations Risk [Member] | Loans Receivable [Member] | Lessors of Non Residential Buildings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 68,000,000
Concentration of credit percentage of total loans	10.00%
Credit Concentrations Risk [Member] | Loans Receivable [Member] | Animal Food Producers [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 40,000,000
Concentration of credit percentage of total loans	6.00%
Credit Concentrations Risk [Member] | Loans Receivable [Member] | Lessor of Residential Buildings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 22,000,000
Concentration of credit percentage of total loans	3.00%
Credit Concentrations Risk [Member] | Loans Receivable [Member] | Commercial Office Space [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of credit percentage of total loans	1.00%
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		129,343,000
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 190,702,000	$ 231,785,000
Interest income recognized on nonaccrual loans	2,000
Consumer Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	166,891,000
Interest income recognized on nonaccrual loans	33,000
Interest income on amortized cost basis	$ 0