Income taxes (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Income taxes
Income tax expense (benefit)		$ 1,110,000	$ 3,375,000
Effective income tax rate		24.30%	26.20%
Split dollar life insurance policy	$ 1,000,000
Unrecognized tax benefits, income tax penalties accrued	0	$ 0	$ 0
Income Tax Examination, Penalties and Interest Expense		2,000
Income tax examination, penalties and interest accrued	$ 0	$ 0	$ 0