Supplemental disclosure of cash flow information (Details Textual) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Redeemable Preferred Stock [Member]
Supplemental Disclosure Of Cash Flow Information [Line Items]
Stock Issued During Period, Shares, Issued for Services	8,421	8,615	5,957
Stock Issued During Period, Shares, Conversion of Convertible Securities	11,558	7,195	4,756
Common Stock [Member]
Supplemental Disclosure Of Cash Flow Information [Line Items]
Stock Issued During Period, Shares, Issued for Services	25,156	10,514	18,294