Segment information - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Retail [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 617,671	$ 498,663	$ 1,751,048	$ 1,506,292
Bulk [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	933,955	790,970	2,858,081	2,318,007
Services [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	1,136	7,638	3,409	22,915
Manufacturing Units [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 214,751	$ 399,987	$ 707,517	$ 1,198,707