Property and equipment (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Property And Equipment Details
Production equipment	$ 2,943,000	$ 5,201,000
Leasehold improvements	502,000	3,344,000
Computer hardware and software/lab equipment	4,373,000	9,002,000
Office furniture and equipment	1,100,000	1,485,000
Property and equipment, gross	8,918,000	19,032,000
Less: Accumulated depreciation	(7,853,000)	(17,827,000)
Property and equipment, net	$ 1,065,000	$ 1,205,000