Note 2 - Liquidity and Capital Resources (Details Textual) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Net Income (Loss) Attributable to Parent	$ (6,229)	$ (9,830)	$ (6,281)	$ (8,011)	$ (6,672)	$ (4,786)	$ (22,340)	$ (19,469)
Net Cash Provided by (Used in) Operating Activities							(15,370)	(16,237)
Cash and Cash Equivalents, at Carrying Value	94,031			$ 117,367			94,031	$ 117,367	$ 110,890
Working Capital (Deficit)	$ 94,204						$ 94,204