Investment Securities - Summary of Amortized Cost and Estimated Fair Value (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	$ 128,974	$ 101,335
Gross Unrealized Gains	160	233
Gross Unrealized Losses	(11,036)	(10,216)
Fair value	118,098	91,352
Mortgage-backed securities - U.S. Government Sponsored Enterprises (GSEs) [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	71,266	48,399
Gross Unrealized Gains	153	219
Gross Unrealized Losses	(6,578)	(5,984)
Fair value	64,841	42,634
U.S. government agency securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	11,260	6,260
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,078)	(969)
Fair value	10,182	5,291
Obligations of state and political subdivisions [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	44,056	44,059
Gross Unrealized Gains	2	12
Gross Unrealized Losses	(3,378)	(3,262)
Fair value	40,680	40,809
Small business association (SBA) securities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized cost	2,392	2,617
Gross Unrealized Gains	5	2
Gross Unrealized Losses	(2)	(1)
Fair value	$ 2,395	$ 2,618