Investment Securities - Summary of Amortized Cost and Held-to-maturity, Gross Unrealized Gains and Losses, and Fair Value of Investment Securities Available for Sale (Detail) - USD ($)	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	$ 146,975,000		$ 120,372,000
Gross Unrealized Gains	337,000		1,280,000
Gross Unrealized Losses	(7,191,000)		(6,162,000)
Allowance for Credit Losses	0		0
Fair Value	140,121,000		115,490,000
Held-to-Maturity, Amortized Cost	35,845,000		36,735,000
Gross Unrecognized Gain	0		0
Gross Unrecognized Losses	(2,637,000)		(2,499,000)
Held-to-maturity, Fair value	33,208,000		34,236,000
Allowance for Credit Losses	(502,000)		(512,000)
US Government Agency securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	12,841,000		12,711,000
Gross Unrealized Gains	120,000		279,000
Gross Unrealized Losses	(5,000)		(5,000)
Allowance for Credit Losses	0		0
Fair Value	12,956,000		12,985,000
US Government Treasury securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	3,979,000		4,925,000
Gross Unrealized Gains	0		17,000
Gross Unrealized Losses	(2,000)		0
Allowance for Credit Losses	0		0
Fair Value	3,977,000		4,942,000
Obligations of state and political subdivisions [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	49,242,000		49,640,000
Gross Unrealized Gains	39,000		420,000
Gross Unrealized Losses	(3,865,000)		(3,015,000)
Allowance for Credit Losses	0		0
Fair Value	45,416,000		47,045,000
Mortgage-backed securities in government-sponsored entities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	80,363,000		50,795,000
Gross Unrealized Gains	178,000		515,000
Gross Unrealized Losses	(3,308,000)		(3,129,000)
Allowance for Credit Losses	0		0
Fair Value	77,233,000		48,181,000
Other securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	550,000		2,301,000
Gross Unrealized Gains	0		49,000
Gross Unrealized Losses	(11,000)		(13,000)
Allowance for Credit Losses	0		0
Fair Value	539,000		2,337,000
Corporate Debentures [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Held-to-Maturity, Amortized Cost	15,000,000		15,000,000
Gross Unrecognized Gain	0		0
Gross Unrecognized Losses	(1,794,000)		(1,592,000)
Held-to-maturity, Fair value	13,206,000		13,408,000
Allowance for Credit Losses	(502,000)	$ (507,000)	(512,000)	$ (586,000)	$ (533,000)	$ 0
Structured Mortgage-backed Securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Held-to-Maturity, Amortized Cost	20,845,000		21,735,000
Gross Unrecognized Gain	0		0
Gross Unrecognized Losses	(843,000)		(907,000)
Held-to-maturity, Fair value	20,002,000		20,828,000
Allowance for Credit Losses	$ 0		$ 0