Note 2 - Basis of Presentation, Principles of Consolidation, Significant Accounting Policies and Liquidity (Details Textual) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($) shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($) shares	Dec. 31, 2022 USD ($)
Number of Operating Segments			1
Retained Earnings (Accumulated Deficit)	$ (115,726)		$ (115,726)		$ (101,835)
Cash and Cash Equivalents, at Carrying Value	$ 32,172		$ 32,172		$ 43,145
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares	6.4	4.9	6.3	4.8
General and Administrative Expense [Member]
Legal Fees	$ 400	$ 800	$ 900	$ 800