Commitments and contingencies (Details Textual) - USD ($)	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Commitments and Contingencies [Line Items]
Estimated Litigation Liability	$ 8,000,000
Litigation Settlement, Expense	100,000
Property, Plant and Equipment, Net	5,256,000	$ 5,915,000
Liens Under Foreign Tax Authority [Member]
Commitments and Contingencies [Line Items]
Property, Plant and Equipment, Net	$ 500,000