Quarterly report pursuant to Section 13 or 15(d)

Note 2 - Basis of Presentation, Principles of Consolidation, Significant Accounting Policies and Liquidity (Details Textual)

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Note 2 - Basis of Presentation, Principles of Consolidation, Significant Accounting Policies and Liquidity (Details Textual)
$ in Thousands, shares in Millions
3 Months Ended 9 Months Ended
Jan. 29, 2021
Sep. 30, 2021
USD ($)
shares
Jun. 30, 2021
USD ($)
Mar. 31, 2021
USD ($)
Sep. 30, 2020
USD ($)
shares
Jun. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Sep. 30, 2021
USD ($)
shares
Sep. 30, 2020
USD ($)
shares
Dec. 31, 2020
USD ($)
Net Income (Loss) Attributable to Parent, Total   $ (4,379) $ (4,244) $ (4,445) $ (3,395) $ (10,112) $ (1,209) $ (13,069) $ (14,716)  
Net Cash Provided by (Used in) Operating Activities, Total               (14,693) $ (14,647)  
Retained Earnings (Accumulated Deficit), Ending Balance   (69,984)           (69,984)   $ (56,916)
Cash and Cash Equivalents, at Carrying Value, Ending Balance   $ 75,178           $ 75,178   $ 15,173
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares   4.5     3.8     4.1 3.4  
Reverse Stock Split [Member]                    
Stockholders' Equity Note, Stock Split, Conversion Ratio 6