Property and Equipment and Assets Held For Sale (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 3,397		$ 3,397		$ 3,411
Less: accumulated depreciation	(2,684)		(2,684)		(2,314)
Property and equipment, net	713		713		1,097
Depreciation	200	$ 300	399	$ 514
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	1,531		$ 1,531		1,557
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		371
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	47		$ 47		47
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful life			5 years
Property and equipment at cost	137		$ 137		137
Computer software
Property, Plant and Equipment [Line Items]
Useful life			3 years
Property and equipment at cost	1,043		$ 1,043		1,043
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment at cost	210		210		201
Projects in progress
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 58		$ 58		$ 55