Income taxes (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income taxes
Income tax expense (benefit)	$ 590,000	$ 1,110,000	$ 965,000	$ 2,710,000
Effective income tax rate	31.80%	28.90%	30.60%	27.90%