Income taxes (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Income taxes
Income tax expense (benefit)	$ 385,000	$ 955,000	$ (200,000)	$ 375,000
Effective income tax rate	25.40%	27.60%	30.90%	28.90%