Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Finance lease right-of-use asset	$ 13		$ 13		$ 13
Property and equipment at cost	3,345		3,345		3,084
Less: accumulated depreciation	(2,757)		(2,757)		(2,664)
Property and equipment, net	588		588		420
Depreciation	43	$ 48	143	$ 140
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,308		$ 1,308		1,281
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)			3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)			15 years
Tooling
Property, Plant and Equipment [Line Items]
Property and equipment, gross	324		$ 324		240
Tooling | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)			2 years
Tooling | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)			5 years
Vehicles
Property, Plant and Equipment [Line Items]
Property and equipment, gross	83		$ 83		47
Useful life (in years)			5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	86		$ 86		137
Useful life (in years)			5 years
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,189		$ 1,189		1,057
Useful life (in years)			3 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	169		$ 169		169
UV - Robots
Property, Plant and Equipment [Line Items]
Property and equipment, gross	105		$ 105		0
Useful life (in years)			5 years
Projects in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 68		$ 68		$ 140