Loans and allowances for loan losses - Classified by type (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (3,681)	$ (3,574)	$ (3,423)	$ (3,256)	$ (3,272)	$ (3,370)
Percentage of class of loans to loan portfolio (in percent)	100.00%		100.00%
Loans
Total loans	$ 605,408		$ 575,008
Deferred (fees) and costs, net	678		803
Less: allowance for credit losses	(3,681)	(3,574)	(3,423)	(3,256)	(3,272)	(3,370)
Total loans, net	602,405		572,388
Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (290)	(259)	$ (314)	(328)	(315)	(271)
Percentage of class of loans to loan portfolio (in percent)	8.12%		8.26%
Loans
Total loans	$ 49,147		$ 47,495
Less: allowance for credit losses	(290)	(259)	(314)	(328)	(315)	(271)
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (2,015)	(2,119)	$ (1,923)	(1,795)	(1,891)	(2,189)
Percentage of class of loans to loan portfolio (in percent)	51.21%		50.54%
Loans
Total loans	$ 310,012		$ 290,590
Less: allowance for credit losses	(2,015)	(2,119)	(1,923)	(1,795)	(1,891)	(2,189)
Consumer real estate secured by 1-4 family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (427)	(428)	$ (432)	(365)	(322)	(185)
Percentage of class of loans to loan portfolio (in percent)	21.52%		22.35%
Loans
Total loans	$ 130,285		$ 128,532
Less: allowance for credit losses	(427)	(428)	(432)	(365)	(322)	(185)
Residential | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (84)	(57)	$ (86)	(61)	(51)	(79)
Percentage of class of loans to loan portfolio (in percent)	2.16%		1.82%
Loans
Total loans	$ 13,080		$ 10,471
Less: allowance for credit losses	(84)	(57)	(86)	(61)	(51)	(79)
Commercial | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (206)	(202)	$ (228)	(267)	(264)	(192)
Percentage of class of loans to loan portfolio (in percent)	5.96%		6.44%
Loans
Total loans	$ 36,067		$ 37,024
Less: allowance for credit losses	(206)	(202)	(228)	(267)	(264)	(192)
Owner occupied | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (461)	(437)	$ (409)	(379)	(391)	(867)
Percentage of class of loans to loan portfolio (in percent)	21.28%		21.33%
Loans
Total loans	$ 128,783		$ 122,666
Less: allowance for credit losses	(461)	(437)	(409)	(379)	(391)	(867)
Non-owner occupied | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (1,469)	(1,596)	$ (1,467)	(1,376)	(1,460)	(1,289)
Percentage of class of loans to loan portfolio (in percent)	26.86%		26.93%
Loans
Total loans	$ 162,621		$ 154,855
Less: allowance for credit losses	(1,469)	(1,596)	(1,467)	(1,376)	(1,460)	(1,289)
Multifamily | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (84)	(86)	$ (44)	(40)	(40)	(33)
Percentage of class of loans to loan portfolio (in percent)	3.02%		2.22%
Loans
Total loans	$ 18,293		$ 12,743
Less: allowance for credit losses	(84)	(86)	(44)	(40)	(40)	(33)
Farmland | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (1)		$ (3)
Percentage of class of loans to loan portfolio (in percent)	0.05%		0.06%
Loans
Total loans	$ 315		$ 326
Less: allowance for credit losses	(1)		(3)
Home equity lines | Consumer real estate secured by 1-4 family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (32)	(32)	$ (40)	(63)	(33)	(11)
Percentage of class of loans to loan portfolio (in percent)	3.68%		3.75%
Loans
Total loans	$ 22,281		$ 21,557
Less: allowance for credit losses	(32)	(32)	(40)	(63)	(33)	(11)
First deed of trust | Consumer real estate secured by 1-4 family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (292)	(298)	$ (293)	(219)	(214)	(131)
Percentage of class of loans to loan portfolio (in percent)	15.72%		16.63%
Loans
Total loans	$ 95,196		$ 95,638
Less: allowance for credit losses	(292)	(298)	(293)	(219)	(214)	(131)
Second deed of trust | Consumer real estate secured by 1-4 family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (103)	(98)	$ (99)	(83)	(75)	(43)
Percentage of class of loans to loan portfolio (in percent)	2.12%		1.97%
Loans
Total loans	$ 12,808		$ 11,337
Less: allowance for credit losses	(103)	(98)	(99)	(83)	(75)	(43)
Commercial and industrial loans (except those secured by real estate) | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (726)	(666)	$ (640)	(673)	(549)	(576)
Percentage of class of loans to loan portfolio (in percent)	16.08%		14.99%
Loans
Total loans	$ 97,363		$ 86,203
Less: allowance for credit losses	(726)	(666)	(640)	(673)	(549)	(576)
Guaranteed student loans | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (45)	(55)	$ (57)	(13)	(112)	(52)
Percentage of class of loans to loan portfolio (in percent)	2.34%		3.12%
Loans
Total loans	$ 14,156		$ 17,923
Less: allowance for credit losses	(45)	(55)	(57)	(13)	(112)	(52)
Consumer and other | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: allowance for credit losses	$ (34)	(36)	$ (36)	(35)	(34)	(37)
Percentage of class of loans to loan portfolio (in percent)	0.73%		0.74%
Loans
Total loans	$ 4,445		$ 4,265
Less: allowance for credit losses	$ (34)	$ (36)	$ (36)	$ (35)	$ (34)	$ (37)