Accounting policies (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Retail revenues	$ 6,185,558	$ 5,570,654	$ 18,884,929	$ 18,111,274
Bulk revenues	8,577,456	7,881,464	25,294,821	23,615,787
Services revenues	807,424	111,302	1,054,100	360,758
Manufacturing revenues	3,253,750	3,008,783	4,798,948	5,444,678
Total revenues	$ 18,824,188	$ 16,572,203	$ 50,032,798	$ 47,532,497