Investment Securities - Summary of Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Investment Securities Available for Sale (Detail) - USD ($)	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	$ 164,635,000	$ 153,102,000
Gross Unrealized Gains	860,000	167,000
Gross Unrealized Losses	(6,312,000)	(7,679,000)
Allowance for Credit Losses	0	0
Fair Value	159,183,000	145,590,000
Held-to-Maturity, Amortized Cost	28,083,000	31,967,000
Gross Unrecognized Gain	7,000	6,000
Gross Unrecognized Losses	(1,326,000)	(1,689,000)
Held-to-maturity, Fair value	26,764,000	30,284,000
Allowance for Credit Losses	(421,000)	(459,000)
US Government Agency securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	13,097,000	13,017,000
Gross Unrealized Gains	208,000	96,000
Gross Unrealized Losses	(32,000)	(40,000)
Allowance for Credit Losses	0	0
Fair Value	13,273,000	13,073,000
Obligations of state and political subdivisions [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	51,221,000	51,254,000
Gross Unrealized Gains	26,000	10,000
Gross Unrealized Losses	(3,782,000)	(4,063,000)
Allowance for Credit Losses	0	0
Fair Value	47,465,000	47,201,000
Mortgage-backed securities in government-sponsored entities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	99,909,000	88,289,000
Gross Unrealized Gains	626,000	61,000
Gross Unrealized Losses	(2,490,000)	(3,567,000)
Allowance for Credit Losses	0	0
Fair Value	98,045,000	84,783,000
Other securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	408,000	542,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(8,000)	(9,000)
Allowance for Credit Losses	0	0
Fair Value	400,000	533,000
Corporate Debentures [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Held-to-Maturity, Amortized Cost	12,250,000	15,250,000
Gross Unrecognized Gain	0	0
Gross Unrecognized Losses	(828,000)	(984,000)
Held-to-maturity, Fair value	11,422,000	14,266,000
Allowance for Credit Losses	(421,000)	(459,000)	$ (507,000)	$ (512,000)
Structured Mortgage-backed Securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Held-to-Maturity, Amortized Cost	15,833,000	16,717,000
Gross Unrecognized Gain	7,000	6,000
Gross Unrecognized Losses	(498,000)	(705,000)
Held-to-maturity, Fair value	15,342,000	16,018,000
Allowance for Credit Losses	$ 0	$ 0