Fair value - Financial instruments measured at fair value (Details) - Other Real Estate Owned [Member] - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		$ 336,000
Appraisal or Internal Valuation Technique [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 0	$ 0
Fair Value Measurements, Valuation Techniques		Appraisal or Internal Valuation
Appraisal or Internal Valuation Technique [Member] | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Selling costs		6.00%
Appraisal or Internal Valuation Technique [Member] | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Selling costs		10.00%
Appraisal or Internal Valuation Technique [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Selling costs	7.00%