Note 5 - Leases (Details Textual) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2020 USD ($) ft²	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Mar. 31, 2017 ft²
Short-term and Variable Lease, Cost				$ 300
Lease, Cost				1,500	$ 1,400
Operating Lease, Payments				$ 2,300	2,200
Operating Lease, Weighted Average Remaining Lease Term (Year)		1 year 2 months 12 days		1 year 2 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent		7.59%		7.59%
Sublease Income		$ 700	$ 700	$ 2,100	$ 2,100
Proceeds from Lease Payment, Operating Activity				$ 2,100
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
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