Loans and allowance for credit losses - Loans in Deferral Program Included in Covid-19 Relief (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance	$ 0	$ 202,517,000
% of Loans		2.90%
Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 7,118,000
% of Loans		0.50%
Construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 1,918,000
% of Loans		0.20%
Residential real estate | 1-to-4 family mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 19,201,000
% of Loans		1.80%
Residential real estate | Residential line of credit
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 204,000
% of Loans		0.00%
Residential real estate | Multi-family mortgage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 3,305,000
% of Loans		1.90%
Commercial real estate | Owner occupied
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 19,815,000
% of Loans		2.10%
Commercial real estate | Non-owner occupied
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 139,590,000
% of Loans		8.70%
Consumer and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Outstanding loans balance		$ 11,366,000
% of Loans		3.60%