Loans receivable (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	$ 734,980	$ 2,135,428
Less current portion	734,980	1,400,448
Loans receivable, excluding current portion	0	734,980
Two loans originally aggregating $10,996,290, bearing interest at 6.5% per annum, receivable in aggregate monthly installments of $124,827 to June 2019, and secured by the machinery and equipment of the North Side Water Works plant [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	$ 734,980	$ 2,135,428