Loans - Summary of Information on Non-accrual Loans (Detail) - USD ($)	Jun. 30, 2024	Dec. 31, 2023
Non Performing Loans [Line Items]
Total nonaccrual loans	$ 788,000	$ 1,110,000
Total nonaccrual loans to total loans	0.20%	0.28%
Total nonaccrual loans to total assets	0.14%	0.20%
Commercial Real Estate [Member]
Non Performing Loans [Line Items]
Total nonaccrual loans		$ 422,000
Residential Real Estate First Mortgages [Member]
Non Performing Loans [Line Items]
Total nonaccrual loans	$ 699,000	657,000
Consumer Home Equity and Lines of Credit [Member]
Non Performing Loans [Line Items]
Total nonaccrual loans	$ 89,000	$ 31,000