Regulatory Matters - Schedule of Regulatory Capital Requirements (Detail) $ in Thousands	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Actual, Total Capital (to risk- weighted assets)	$ 55,637	$ 55,506
Actual, Tier 1 Capital (to risk- weighted assets)	51,900	51,820
Actual, Tier 1 Capital (to average assets)	51,900	51,820
Actual, Common Equity Tier 1 (to risk-weighted assets)	$ 51,900	$ 51,820
Actual Ratio, Total Capital (to risk- weighted assets)	0.1553	0.1555
Actual Ratio, Tier 1 Capital (to risk- weighted assets)	0.1448	0.1452
Actual Ratio, Tier 1 Capital (to average assets)	0.0844	0.0869
Actual Ratio, Common Equity Tier 1 (to risk-weighted assets)	0.1448	0.1452
Minimum Capital Requirement, Total Capital (to risk-weighted assets)	$ 28,666	$ 28,555
Minimum Capital Requirement, Tier 1 Capital (to risk-weighted assets)	21,500	21,417
Minimum Capital Requirement, Tier 1 Capital (to average assets)	24,607	23,848
Minimum Capital Requirement, Common Equity Tier 1 (to risk-weighted assets)	$ 16,125	$ 16,062
Minimum Capital Requirement Ratio, Total Capital (to risk-weighted assets)	0.0800	0.0800
Minimum Capital Requirement Ratio, Tier 1 Capital (to risk-weighted assets)	0.0600	0.0600
Minimum Capital Requirement Ratio, Tier 1 Capital (to average assets)	0.0400	0.0400
Minimum Capital Requirement Ratio, Common Equity Tier 1 (to risk-weighted assets)	4.50%	4.50%
Minimum Capital Required to be Well Capitalized, Total Capital (to risk-weighted assets)	$ 35,833	$ 35,694
Minimum Capital Required to be Well Capitalized, Tier 1 Capital (to risk-weighted assets)	28,666	28,555
Minimum Capital Required to be Well Capitalized, Tier 1 Capital (to average assets)	30,759	29,809
Minimum Capital Required to be Well Capitalized, Common Equity Tier 1 (to risk-weighted assets)	$ 23,291	$ 23,201
Minimum Capital Requirement Ratio, Total Capital (to risk-weighted assets)	0.1000	0.1000
Minimum Capital Requirement Ratio, Tier 1 Capital (to risk-weighted assets)	0.0800	0.0800
Minimum Capital Requirement Ratio, Tier 1 Capital (to average assets)	0.0500	0.0500
Minimum Capital Requirement Ratio, Common Equity Tier 1 (to risk-weighted assets)	0.0650	0.0650
Fully Phased In [Member]
Minimum Capital Requirement, Total Capital (to risk-weighted assets)	$ 37,624	$ 37,479
Minimum Capital Requirement, Tier 1 Capital (to risk-weighted assets)	30,458	30,340
Minimum Capital Requirement, Tier 1 Capital (to average assets)	24,607	23,848
Minimum Capital Requirement, Common Equity Tier 1 (to risk-weighted assets)	$ 25,083	$ 24,986
Minimum Capital Requirement Ratio, Total Capital (to risk-weighted assets)	0.1050	0.1050
Minimum Capital Requirement Ratio, Tier 1 Capital (to risk-weighted assets)	0.0850	0.0850
Minimum Capital Requirement Ratio, Tier 1 Capital (to average assets)	0.0400	0.0400
Minimum Capital Requirement Ratio, Common Equity Tier 1 (to risk-weighted assets)	7.00%	7.00%

Common Equity Tier One Capital Required For Adequacy To Risk based Assets.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477270/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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