Loans and allowance for loan losses - Impaired loans (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
With no related allowance recorded
Recorded Investment, after ASU 2016-13	$ 281	$ 291
Unpaid Principle Balance, after ASU 2016-13	281	291
Total
Recorded Investment, after ASU 2016-13	281	291
Unpaid Principle Balance, after ASU 2016-13	281	291
Consumer real estate secured by 1-4 family residential
With no related allowance recorded
Recorded Investment, after ASU 2016-13	259	265
Unpaid Principle Balance, after ASU 2016-13	259	265
Total
Recorded Investment, after ASU 2016-13	259	265
Unpaid Principle Balance, after ASU 2016-13	259	265
Consumer real estate secured by 1-4 family residential | First deed of trust
With no related allowance recorded
Recorded Investment, after ASU 2016-13	159	160
Unpaid Principle Balance, after ASU 2016-13	159	160
Total
Recorded Investment, after ASU 2016-13	159	160
Unpaid Principle Balance, after ASU 2016-13	159	160
Consumer real estate secured by 1-4 family residential | Second deed of trust
With no related allowance recorded
Recorded Investment, after ASU 2016-13	100	105
Unpaid Principle Balance, after ASU 2016-13	100	105
Total
Recorded Investment, after ASU 2016-13	100	105
Unpaid Principle Balance, after ASU 2016-13	100	105
Commercial and industrial loans | Commercial and industrial loans (except those secured by real estate)
With no related allowance recorded
Recorded Investment, after ASU 2016-13	22	26
Unpaid Principle Balance, after ASU 2016-13	22	26
Total
Recorded Investment, after ASU 2016-13	22	26
Unpaid Principle Balance, after ASU 2016-13	$ 22	$ 26