SBA loan servicing activities - Schedule of activity for SBA loan servicing rights (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Beginning of period	$ 8,160
End of period	6,619	$ 8,160
SBA Loan
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Beginning of period	8,160	11,280
Additions	1,229	530
Amortization	(2,982)	(3,650)
End of period	$ 6,407	$ 8,160