Note 13 - Income Taxes (Details Textual) $ / shares in Units, $ in Thousands			12 Months Ended
	Feb. 03, 2022	Feb. 07, 2019	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($)
Income Tax Expense (Benefit), Total			$ 35	$ 25
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			2,549	1,944
Deferred Tax Assets, Valuation Allowance			74,559	72,010
Operating Loss Carryforwards, Subject to Expiration			$ 288,462	227,781
Operating Loss Carry Forwards Annual Limit				$ 14,284
Rights [Member]
Term of Extended Rights Plan (Year)	3 years	3 years
Threshold Percentage of Beneficial Ownership for Significant Dilution in Ownership Interest			4.90%	4.90%
Class of Warrant or Right Number of Rights Per Common Stock Share			1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) | shares			0.001
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares			$ 7.26
Class of Warrant or Right Current Beneficial Ownership Percentage That Will Not Trigger Preferred Share Purchase Rights			4.90%