Allowance for Credit Losses on Loans - Schedule of Gross Charge-Offs by Origination (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 12
2023	61	$ 125
2022	7	4
2021	149	162
2020	171	315
Prior	5	75
Revolving	75	73
Total	480	754
Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	10	49
2021	137	159
2020	164	315
Prior		71
Revolving	10	9
Total	321	603
Consumer Loans [Member] | Non-Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	12
2023	51	34
2022	7	4
2021	12	3
2020	7
Prior	4	4
Revolving	65	64
Total	158	109
Other Real Estate Construction [Member] | Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023		42
Total		$ 42
Home Equity Loan [Member] | Non-Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Prior	1
Total	$ 1