Segment information (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Retail [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 504,616	$ 512,478	$ 1,007,629	$ 1,022,298
Bulk [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	808,964	827,037	1,618,112	1,653,816
Services [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	7,639	7,638	15,277	29,657
Manufacturing [Member]
Segment Reporting Information [Line Items]
Depreciation, Depletion and Amortization	$ 399,426	$ 399,456	$ 798,720	$ 805,945