Note 5 - Leases (Details Textual) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 01, 2018 USD ($)	Aug. 31, 2020 USD ($) ft²	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Oct. 30, 2018 ft²	Mar. 31, 2017 ft²
Short-term and Variable Lease, Cost			$ 100		$ 300
Lease, Cost, Total			$ 400	$ 500	1,100	$ 1,300
Operating Lease, Payments					$ 1,800	2,000
Operating Lease, Weighted Average Remaining Lease Term (Year)			3 years 2 months 12 days		3 years 2 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent			7.64%		7.64%
Write-off of Lease Receivable and Prepaid Commission Assets					$ 0	1,383
The 1020 Marsh Road Facility [Member]
Area of Real Estate Property (Square Foot) | ft²								34,500
Lessee, Operating Lease, Term of Contract (Month)								87 months
Lessee, Operating Lease, Number of Renewal Options								1
Lessee, Operating Lease, Renewal Term (Year)								5 years
The 1020 Marsh Road Facility [Member] | EVA Automation, Inc. [Member]
Proceeds from Lease Payment, Operating Activity					1,200
Lessor, Operating Lease, Term of Contract (Month)	72 months
Incentive to Lessee	$ 900
Lessor, Operating Lease, Abatement Term (Month)	5 months
Write-off of Lease Receivable and Prepaid Commission Assets					1,400
Operating Lease, Lease Income (Loss)				$ 31		$ (13)
Sublease Agreement in Palo Alto, California [Member]
Area of Real Estate Property (Square Foot) | ft²							4,240
Office Space in North Carolina [Member]
Area of Real Estate Property (Square Foot) | ft²		4,128
Lessee, Operating Lease, Term of Contract (Month)		63 months
Lessee, Operating Lease, Monthly Payments		$ 9
Lessee, Operating Lease, Abatement Term (Month)		3 months
The 1020 Marsh Facility [Member]
Sublease Income			$ 400		400
Proceeds from Lease Payment, Operating Activity			$ 600		$ 600