Accounting policies - Revenue recognized and billed on services (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Accounting policies
Revenue recognized to date on contracts in progress	$ 10,234,946	$ 6,109,396
Amounts billed to date on contracts in progress	(12,905,981)	(6,370,855)
Retainage	543,593	237,542
Net contract asset	(2,127,442)	(23,917)
Contract assets	1,098,240	489,961
Contract liabilities	(3,225,682)	(513,878)
Net contract liability	$ (2,127,442)	$ (23,917)