Property, plant and equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,079	$ 2,075
Less accumulated depreciation and amortization	(2,062)	(2,047)
Property, Plant and Equipment, Net	17	28
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	1,231	1,227
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