Note 13 - Income Taxes (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Feb. 03, 2022	Feb. 07, 2019	Dec. 31, 2021	Dec. 31, 2020
Income Tax Expense (Benefit), Total			$ 25	$ 48
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			1,944	(4,055)
Deferred Tax Assets, Valuation Allowance, Total			72,010	$ 70,066
Operating Loss Carryforwards, Total			277,310
Operating Loss Carryforwards, Subject to Expiration			227,781
Operating Loss Carry Forwards Annual Limit			$ 14,284
Rights [Member]
Term of Extended Rights Plan (Year)		3 years
Threshold Percentage of Beneficial Ownership for Significant Dilution in Ownership Interest			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)			0.001
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)			$ 7.26
Class of Warrant or Right Current Beneficial Ownership Percentage That Will Not Trigger Preferred Share Purchase Rights			4.90%
Rights [Member] | Subsequent Event [Member]
Term of Extended Rights Plan (Year)	3 years