Property and Equipment and Assets Held For Sale - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 3,341		$ 3,341		$ 3,375
Less: accumulated depreciation	(2,919)		(2,919)		(2,765)
Property and equipment, net	422		422		610
Depreciation	100	$ 100	200	$ 294
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	1,451		$ 1,451		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	$ 45		$ 45		$ 55