Accounting policies - Revenue recognized and billed on services (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Accounting policies
Revenue recognized to date on contracts in progress	$ 86,655,434	$ 25,469,014
Amounts billed to date on contracts in progress	(94,162,641)	(33,407,182)
Retainage	6,951,198	2,047,969
Net contract asset	(556,009)	(5,890,199)
Contract assets	8,972,740	2,913,722
Contract liabilities	(9,528,749)	(8,803,921)
Net contract liability	$ (556,009)	$ (5,890,199)