Income taxes - Components of Net Loss (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income taxes
Net loss	$ (28,059,807)	$ (15,528,269)	$ (15,190,250)
Foreign
Income taxes
Net loss	(25,268,373)	(15,713,032)	(15,185,931)
Federal
Income taxes
Net loss	$ (2,791,434)	$ 184,763	$ (4,319)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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