Loans and allowance for credit losses - Information on nonaccrual loans (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 286	$ 654
Consumer real estate secured by 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	269	635
Consumer real estate secured by 1-4 family residential | Home equity lines
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		300
Consumer real estate secured by 1-4 family residential | First deed of trust
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	162	164
Consumer real estate secured by 1-4 family residential | Second deed of trust
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	107	171
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate)
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 17	$ 19