Note 2 - Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Retained Earnings (Accumulated Deficit), Total	$ (150,103)	$ (140,604)
Cash and Cash Equivalents, at Carrying Value, Total	$ 1,835	$ 7,363
Cash, Percentage Held in One Financial Institution	98.00%
Cash, Uninsured Amount	$ 1,600