Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 5,258	$ 3,130
Less: accumulated depreciation	(2,829)	(2,674)
Property, Plant and Equipment, Net	2,429	456
Depreciation	$ 266	184	$ 615
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	2 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	15 years
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 2,864	$ 1,289
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years	3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	15 years	15 years
Tooling
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 851	$ 851
Tooling | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	2 years	2 years
Tooling | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years	5 years
Vehicles
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 39	$ 0
Property and equipment, useful life	5 years	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 104	$ 85
Property and equipment, useful life	5 years	5 years
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 581	$ 378
Property and equipment, useful life	3 years	3 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 509	$ 509
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 310	$ 18