Accounting policies - Disaggregated revenue (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Total Revenue	$ 15,889,239	$ 18,053,284	$ 51,183,023	$ 47,672,013
Retail revenue [Member]
Total Revenue	6,271,220	6,185,558	19,941,395	18,884,929
Bulk revenue [Member]
Total Revenue	6,449,757	7,806,552	20,502,121	22,934,036
Services revenue [Member]
Total Revenue	95,980	807,424	287,349	1,054,100
Manufacturing revenue [Member]
Total Revenue	$ 3,072,282	$ 3,253,750	$ 10,452,158	$ 4,798,948