Income taxes - Components of income before income taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income taxes
Foreign (not subject to income taxes)	$ 12,274,013	$ 10,699,269	$ 10,002,233
Mexico	(131,596)	10,922,374	(742,367)
United States	8,952,083	9,412,015	27,649,330
Income before income taxes	21,094,500	31,033,658	36,909,196
Discontinued operations	290,635	(10,355,184)	1,086,744
Income before income taxes	$ 21,385,135	$ 20,678,474	$ 37,995,940