Loans - Additional Information (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Industry	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans serviced for others		$ 132,200,000		$ 137,500,000
Total Loans		680,980,000		626,958,000
Outstanding balance of commercial loans classified under credit risk, minimum amount		500,000
Interest income	$ 11,000		$ 37,000
Consumer Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		167,419,000
Interest income recognized on nonaccrual loans		22,000
Interest income on amortized cost basis		0
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		188,910,000		$ 231,785,000
Interest income	$ 2,000		$ 6,000
Interest income recognized on nonaccrual loans		$ 1,000
Credit Concentration Risk [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of industries for credit concentrations | Industry		2
Credit Concentration Risk [Member] | Loans Receivable [Member] | Lessors of Non-residential Buildings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		$ 62,900,000
Concentration of credit percentage of total loans		9.00%
Credit Concentration Risk [Member] | Loans Receivable [Member] | Manufacturers of Animal Food [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans		$ 39,600,000
Concentration of credit percentage of total loans		6.00%