Income taxes - Components of income before income taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income taxes
Foreign (not subject to income taxes)	$ 10,699,269	$ 10,002,233	$ 6,958,583
Mexico	10,922,374	(742,367)	(987,279)
United States	9,412,015	27,649,330	1,394,642
Income before income taxes	31,033,658	36,909,196	7,365,946
Discontinued operations	(10,355,184)	1,086,744	2,371,049
Income before income taxes	$ 20,678,474	$ 37,995,940	$ 9,736,995