Summary of significant accounting policies (Details Textual) - shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Summary Of Significant Accounting Policies [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion (in shares)	10,296	9,699
Warrant [Member]
Summary Of Significant Accounting Policies [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,020,825	1,020,829
Restricted Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	775,000	88,999