Note 1 - Company Overview (Details Textual) $ / shares in Units, shares in Thousands, $ in Thousands						3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 22, 2024	Mar. 20, 2024 $ / shares shares	Feb. 08, 2024	Aug. 11, 2023 $ / shares	May 09, 2023	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) $ / shares	Dec. 22, 2021 $ / shares
Net Income (Loss) Attributable to Parent						$ (1,773)	$ (6,270)	$ (10,564)	$ (66,857)
Net Cash Provided by (Used in) Operating Activities								2,174	(8,458)
Cash and Cash Equivalents, at Carrying Value						16,071	$ 27,955	16,071	$ 27,955
Retained Earnings (Accumulated Deficit)						$ (710,379)		$ (710,379)		$ (699,815)
Number of Restructuring Plans						2		2
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares		$ 0.0001		$ 0.0001		$ 0.0001		$ 0.0001		$ 0.0001	$ 0.0001
Restructuring Charges								$ 693
Employee Severance [Member]
Restructuring Charges								683		$ 1,600
Employee Severance [Member] | Approximation [Member]
Restructuring Charges						$ (10)		$ 600
Employee Severance [Member] | Employees [Member]
Restructuring and Related Cost, Number of Positions Eliminated			17		50
Employee Severance [Member] | Contractors [Member]
Restructuring and Related Cost, Number of Positions Eliminated			26		15
Fractional Shares [Member]
Stock Issued During Period, Shares, Reverse Stock Splits (in shares) | shares		0
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	12	12
Reverse Stock Split [Member] | Minimum [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio				2
Reverse Stock Split [Member] | Maximum [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio				30