Basis of Presentation - Additional Information (Detail) - USD ($)		3 Months Ended
	Jan. 01, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
CECL, allowance for credit losses		$ 4,596,000	$ 2,290,000	$ 4,156,000	$ 4,026,000
Allowance for credit losses for held to maturity securities		63,000
Undivided profits		36,930,000	$ 37,030,000
Allowance for credit losses for available for sale securities		0
Debt securities available for sale securities accrued interest allowance for credit loss		2,000,000.0
Debt securities held-to-maturity accrued interest allowance for credit loss		$ 358,000
Project defaults utilization period for third-party forecast		2 years
Reversion period to average economic forecast for remainder for portfolio life		1 year
Review threshold of loans experiencing financial difficulty with relationship exposure for collateral dependent		$ 100,000
T-Bill [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Debt instrument term		10 years
U.S. Government Agencies [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses for held to maturity securities		$ 0
ASU 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2023
Change in accounting principle, accounting standards update, adopted		true
CECL, allowance for credit losses	$ 4,847,000
Allowance for credit losses for held to maturity securities	70,000
ASU 2016-13 [Member] | Unfunded Loan Commitment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
CECL, allowance for credit losses	150,000
ASU 2016-13 [Member] | Cumulative Effect, Period of Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
CECL, allowance increase	2,410,000
Allowance for credit losses for held to maturity securities	70,000
Undivided profits	1,900,000
ASU 2016-13 [Member] | Cumulative Effect, Period of Adoption [Member] | Unfunded Loan Commitment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
CECL, allowance for credit losses	$ 9,000
ASU 2022-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adoption date		Jan. 01, 2023
Change in accounting principle, accounting standards update, adopted		true