Property and Equipment and Assets Held For Sale (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 3,602		$ 3,602		$ 4,690
Less: accumulated depreciation	(2,095)		(2,095)		(2,365)
Property and equipment, net	1,507		1,507		2,325
Depreciation	171	$ 200	348	$ 336
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	1,755		$ 1,755		2,231
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life			3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life			15 years
Tooling
Property, Plant and Equipment [Line Items]
Property and equipment at cost	371		$ 371		863
Tooling | Minimum
Property, Plant and Equipment [Line Items]
Useful life			2 years
Tooling | Maximum
Property, Plant and Equipment [Line Items]
Useful life			5 years
Vehicles
Property, Plant and Equipment [Line Items]
Useful life			5 years
Property and equipment at cost	86		$ 86		39
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life			5 years
Property and equipment at cost	137		$ 137		170
Computer software
Property, Plant and Equipment [Line Items]
Useful life			3 years
Property and equipment at cost	977		$ 977		977
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment at cost	201		201		256
Projects in progress
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 75		$ 75		154
Discontinued Operations, Held-for-sale | Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost					$ 410