Property, Plant and Equipment - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Less: accumulated depreciation and amortization	$ (14,582)	$ (13,544)
Property, plant and equipment, net	1,989	2,476
Research Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment	6,925	6,815
Office Furniture and Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment	1,040	980
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment	2,236	1,887
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment	$ 6,370	$ 6,338