Property and Equipment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Gross		$ 2,668	$ 2,643
Less accumulated depreciation and amortization		1,585	1,189
Total		1,083	1,454
Research and Development Equipment [Member]
Property, Plant and Equipment, Gross		$ 1,552	1,349
Property, Plant and Equipment, Useful Life		5 years
Office and Computer Equipment [Member]
Property, Plant and Equipment, Gross		$ 742	672
Property, Plant and Equipment, Useful Life		3 years
Autos [Member]
Property, Plant and Equipment, Gross		$ 54	305
Property, Plant and Equipment, Useful Life		5 years
Furniture and Fixtures [Member]
Property, Plant and Equipment, Gross		$ 37	34
Property, Plant and Equipment, Useful Life		7 years
Leasehold Improvements [Member]
Property, Plant and Equipment, Gross	[1]	$ 283	283
Construction In Process [Member]
Property, Plant and Equipment, Gross

[1] Shorter of lease term or estimated useful life