Property and equipment (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Depreciation, Depletion and Amortization		$ 3,195	$ 2,773	$ 3,046
Impairment of Long-Lived Assets Held-for-use	$ 400
Property, Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation, Depletion and Amortization		$ 2,100	$ 1,900	$ 2,500