Note 2 - Liquidity and Capital Resources (Details Textual) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Net Income (Loss) Attributable to Parent, Total	$ (4,786)	$ (3,538)
Net Cash Provided by (Used in) Operating Activities, Total	(4,878)	(4,408)
Cash and Cash Equivalents, at Carrying Value, Total	131,486	$ 137,574	$ 136,377
Working Capital (Deficit)	$ 134,526
Proceeds from Issuance or Sale of Equity, Total			$ 113,486