Loans and Allowance for Credit Losses on Loans - Schedule of Accounts, Notes, Loans and Financing Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Total loans	$ 437,991		$ 430,031
Allowance for credit losses on loans	(3,445)	$ (3,451)	(3,390)	$ (3,349)	$ (3,319)	$ (3,581)
Net loans	434,546		426,641
CRE [Member]
Total loans	85,696		86,566
Allowance for credit losses on loans	(720)	(745)	(830)	(788)	(806)	(942)
MF [Member]
Total loans	5,824		7,582
Allowance for credit losses on loans	(60)	(107)	(76)	(71)	(49)	(54)
C+I [Member]
Total loans	24,096		25,511
Allowance for credit losses on loans	(237)	(234)	(236)	(288)	(277)	(184)
ADL [Member]
Total loans	13,599		17,520
Allowance for credit losses on loans	(78)	(70)	(105)	(101)	(70)	(138)
RES [Member]
Total loans	279,832		268,943
Allowance for credit losses on loans	(1,652)	(1,608)	(1,601)	(1,736)	(1,910)	(2,048)
HELOC [Member]
Total loans	16,678		14,093
Allowance for credit losses on loans	(174)	(171)	(156)	(161)	(85)	(81)
CON [Member]
Total loans	12,266		9,816
Allowance for credit losses on loans	$ (477)	$ (442)	$ (357)	$ (204)	$ (109)	$ (100)