Loans and allowance for loan losses - Aging of recorded investment in past due loans and leases (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 614,772	$ 575,008
Recorded Investment, 90 Days and Accruing		2,228
Recorded Investment, 90 Days and Accruing	$ 1,570
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Percentage of loans	98.00%
United States Department of Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Percentage of loans	100.00%
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 611,475	570,722
Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	3,297	4,286
30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	395	1,540
60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,310	518
Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,592	2,228
Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	52,908	47,495
Construction and land development | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	52,908	47,495
Construction and land development | Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	16,661	10,471
Construction and land development | Residential | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	16,661	10,471
Construction and land development | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	36,247	37,024
Construction and land development | Commercial | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	36,247	37,024
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	313,906	290,590
Commercial real estate | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	313,890	290,590
Commercial real estate | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	16
Commercial real estate | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	16
Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	129,747	122,666
Commercial real estate | Owner occupied | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	129,747	122,666
Commercial real estate | Non-owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	165,979	154,855
Commercial real estate | Non-owner occupied | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	165,963	154,855
Commercial real estate | Non-owner occupied | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	16
Commercial real estate | Non-owner occupied | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	16
Commercial real estate | Multifamily
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	17,862	12,743
Commercial real estate | Multifamily | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	17,862	12,743
Commercial real estate | Farmland
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	318	326
Commercial real estate | Farmland | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	318	326
Consumer real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	130,664	128,532
Consumer real estate | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	130,544	128,391
Consumer real estate | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	120	141
Consumer real estate | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		116
Consumer real estate | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	120	25
Consumer real estate | Home equity lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	22,384	21,557
Consumer real estate | Home equity lines | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	22,264	21,449
Consumer real estate | Home equity lines | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	120	108
Consumer real estate | Home equity lines | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		83
Consumer real estate | Home equity lines | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	120	25
Consumer real estate | First deed of trust
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	94,497	95,638
Consumer real estate | First deed of trust | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	94,497	95,638
Consumer real estate | Second deed of trust
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	13,783	11,337
Consumer real estate | Second deed of trust | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	13,783	11,304
Consumer real estate | Second deed of trust | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		33
Consumer real estate | Second deed of trust | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		33
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	98,878	86,203
Recorded Investment, 90 Days and Accruing	375
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate) | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	97,805	86,203
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate) | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,073
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate) | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	698
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate) | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	375
Commercial and industrial loans | Guaranteed student loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	13,645	17,923
Recorded Investment, 90 Days and Accruing		2,228
Recorded Investment, 90 Days and Accruing	1,195
Commercial and industrial loans | Guaranteed student loans | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	11,579	14,512
Commercial and industrial loans | Guaranteed student loans | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	2,066	3,411
Commercial and industrial loans | Guaranteed student loans | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	379	690
Commercial and industrial loans | Guaranteed student loans | 60 to 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	492	493
Commercial and industrial loans | Guaranteed student loans | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	1,195	2,228
Commercial and industrial loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	4,771	4,265
Commercial and industrial loans | Consumer and other | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	4,749	3,531
Commercial and industrial loans | Consumer and other | Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	22	734
Commercial and industrial loans | Consumer and other | 30 to 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans		$ 734
Commercial and industrial loans | Consumer and other | Greater than 90 Days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	$ 22