Cost of revenues and general and administrative expenses (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	$ 18,677,584	$ 14,840,156	$ 17,011,041
Employee costs [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	7,598,829	6,841,274	6,671,510
Insurance [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	782,013	802,386	923,089
Professional fees [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	1,101,938	941,193	1,424,927
Directors' fees and expenses [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	774,769	754,145	686,228
Depreciation [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	384,045	218,032	278,478
NSC project expenses [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	3,011,989	1,976,408	3,606,332
Amortization Of Intangibles [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	1,410,143	89,896	89,896
Other [Member]
Cost of revenues and general and administrative expenses [Line Items]
General and Administrative Expense	$ 3,613,858	$ 3,216,822	$ 3,330,581