Investment Securities - Summary of Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Investment Securities Available for Sale (Detail) - USD ($)	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	$ 152,111,000		$ 120,372,000
Gross Unrealized Gains	1,909,000		1,280,000
Gross Unrealized Losses	(4,705,000)		(6,162,000)
Allowance for Credit Losses	0		0
Fair Value	149,315,000		115,490,000
Held-to-Maturity, Amortized Cost	34,626,000		36,735,000
Gross Unrecognized Gain	2,000		0
Gross Unrecognized Losses	(1,805,000)		(2,499,000)
Held-to-maturity, Fair value	32,823,000		34,236,000
Allowance for Credit Losses	(471,000)		(512,000)
US Government Agency securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	11,935,000		12,711,000
Gross Unrealized Gains	442,000		279,000
Gross Unrealized Losses	0		(5,000)
Allowance for Credit Losses	0		0
Fair Value	12,377,000		12,985,000
US Government Treasury securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost			4,925,000
Gross Unrealized Gains			17,000
Gross Unrealized Losses			0
Allowance for Credit Losses			0
Fair Value			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	51,124,000		49,640,000
Gross Unrealized Gains	134,000		420,000
Gross Unrealized Losses	(2,663,000)		(3,015,000)
Allowance for Credit Losses	0		0
Fair Value	48,595,000		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	88,528,000		50,795,000
Gross Unrealized Gains	1,333,000		515,000
Gross Unrealized Losses	(2,033,000)		(3,129,000)
Allowance for Credit Losses	0		0
Fair Value	87,828,000		48,181,000
Other securities [Member]
Debt Securities Available For Sale Reconciliation Of Fair Value To Amortized Cost [Line Items]
Amortized Cost	524,000		2,301,000
Gross Unrealized Gains	0		49,000
Gross Unrealized Losses	(9,000)		(13,000)
Allowance for Credit Losses	0		0
Fair Value	515,000		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	(1,198,000)		(1,592,000)
Held-to-maturity, Fair value	13,802,000		13,408,000
Allowance for Credit Losses	(471,000)	$ (502,000)	(512,000)	$ (512,000)	$ (586,000)	$ 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	19,626,000		21,735,000
Gross Unrecognized Gain	2,000		0
Gross Unrecognized Losses	(607,000)		(907,000)
Held-to-maturity, Fair value	19,021,000		20,828,000
Allowance for Credit Losses	$ 0		$ 0