Property, plant and equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,083	$ 2,079
Less accumulated depreciation and amortization	(2,072)	(2,062)
Property, Plant and Equipment, Net	11	17
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,235	1,231
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	435	435
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	90	90
Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 323	$ 323