Loans and allowance for loan losses - Information on the risk rating of loans (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 540,683	$ 526,457	$ 526,457
Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,078		3,003
Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans	527,181	490,480
Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans	10,804	30,644
Risk Rated 6
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,698	5,333
Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total loans	40,546	49,149	49,149
Construction and land development | Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	8,437	6,805	6,805
Construction and land development | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans	32,109	42,344	42,344
Construction and land development | Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans	37,909	46,512
Construction and land development | Risk Rated 1-4 | Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	8,437	6,805
Construction and land development | Risk Rated 1-4 | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans	29,472	39,707
Construction and land development | Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,637	2,637
Construction and land development | Risk Rated 5 | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,637	2,637
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	289,921	255,537	255,537
Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	122,067	113,108	113,108
Commercial real estate | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	155,981	129,786	129,786
Commercial real estate | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans	11,309	11,666	11,666
Commercial real estate | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total loans	564	977	977
Commercial real estate | Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans	281,825	230,181
Commercial real estate | Risk Rated 1-4 | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	118,343	103,370
Commercial real estate | Risk Rated 1-4 | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	151,609	114,168
Commercial real estate | Risk Rated 1-4 | Multifamily
Financing Receivable, Recorded Investment [Line Items]
Total loans	11,309	11,666
Commercial real estate | Risk Rated 1-4 | Farmland
Financing Receivable, Recorded Investment [Line Items]
Total loans	564	977
Commercial real estate | Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans	6,551	21,513
Commercial real estate | Risk Rated 5 | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,454	6,181
Commercial real estate | Risk Rated 5 | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,097	15,332
Commercial real estate | Risk Rated 6
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,545	3,843
Commercial real estate | Risk Rated 6 | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,270	3,557
Commercial real estate | Risk Rated 6 | Non-owner occupied
Financing Receivable, Recorded Investment [Line Items]
Total loans	275	286
Consumer real estate secured by 1-4 family residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	92,525	92,372	92,372
Consumer real estate secured by 1-4 family residential | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	19,891	17,977	17,977
Consumer real estate secured by 1-4 family residential | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	65,704	62,277	62,277
Consumer real estate secured by 1-4 family residential | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	6,930	12,118	12,118
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4
Financing Receivable, Recorded Investment [Line Items]
Total loans	90,295	86,478
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4 | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	19,026	17,054
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4 | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	64,661	57,932
Consumer real estate secured by 1-4 family residential | Risk Rated 1-4 | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	6,608	11,492
Consumer real estate secured by 1-4 family residential | Risk Rated 5
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,190	4,657
Consumer real estate secured by 1-4 family residential | Risk Rated 5 | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	565	623
Consumer real estate secured by 1-4 family residential | Risk Rated 5 | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	553	3,605
Consumer real estate secured by 1-4 family residential | Risk Rated 5 | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	72	429
Consumer real estate secured by 1-4 family residential | Risk Rated 6
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,040	1,237
Consumer real estate secured by 1-4 family residential | Risk Rated 6 | Home equity lines
Financing Receivable, Recorded Investment [Line Items]
Total loans	300	300
Consumer real estate secured by 1-4 family residential | Risk Rated 6 | First deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	490	740
Consumer real estate secured by 1-4 family residential | Risk Rated 6 | Second deed of trust
Financing Receivable, Recorded Investment [Line Items]
Total loans	250	197
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans	91,603	100,421	100,421
Commercial and industrial loans | Guaranteed student loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	22,010	25,975	$ 25,975
Commercial and industrial loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,078	3,003
Commercial and industrial loans | Risk Rated 1-4 | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans	91,088	98,362
Commercial and industrial loans | Risk Rated 1-4 | Guaranteed student loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	22,010	25,975
Commercial and industrial loans | Risk Rated 1-4 | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,054	2,972
Commercial and industrial loans | Risk Rated 5 | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans	426	1,806
Commercial and industrial loans | Risk Rated 5 | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans		31
Commercial and industrial loans | Risk Rated 6 | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Recorded Investment [Line Items]
Total loans	89	$ 253
Commercial and industrial loans | Risk Rated 6 | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 24