Commitments and contingencies (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]    
Total commitments to extend credit $ 148,395 $ 150,974
Standby letters of Credit    
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]    
Total commitments to extend credit 4,771 4,934
Undisbursed credit lines    
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]    
Total commitments to extend credit 111,349 107,130
Commitments to extend or originate credit    
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]    
Total commitments to extend credit $ 32,275 $ 38,910