Bank segment - Collateral-dependent loans (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Residential real estate property | Real estate | Residential 1-4 family
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	$ 4,500	$ 3,493
Residential real estate property | Real estate | Home equity line of credit
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	1,034	1,294
Residential real estate property | Real estate | Residential land
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	397	300
Commercial real estate | Real estate | Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	1,200	1,221
Collateral pledged
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	7,693	7,000
Collateral pledged | Real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	7,131	6,308
Business assets | Commercial
Financing Receivable, Nonaccrual [Line Items]
Collateral-dependent loans, amortized cost	$ 562	$ 692