Property and Equipment and Assets Held For Sale - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 3,370			$ 3,370		$ 3,375
Less: accumulated depreciation	(2,995)			(2,995)		(2,765)
Property and equipment, net	375			375		610
Depreciation	100	$ 100		277	$ 399
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	1,457			1,457		1,511
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	394			394		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	211			211		211
Finance lease right-of-use asset
Property, Plant and Equipment [Line Items]
Property and equipment at cost	13			13		0
Projects in progress
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 68			$ 68		$ 55