Note 8 - Preferred Stock and Common Stock Warrants (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		1 Months Ended	3 Months Ended
	Apr. 15, 2022	Mar. 31, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Common Stock Warrants [Member]
Fair Value Adjustment of Warrants			$ 6.3	$ 2.0
Series A Convertible Preferred Stock [Member]
Temporary Equity, Shares Outstanding (in shares)		75,938	75,938		73,713
Temporary Equity, Par or Stated Value Per Share (in dollars per share)					$ 0.0001
Preferred Stock, Convertible, Conversion Price (in dollars per share)		$ 6.39	$ 6.39
Series B Convertible Preferred Stock [Member]
Temporary Equity, Shares Outstanding (in shares)		72,556	72,556		70,433
Temporary Equity, Par or Stated Value Per Share (in dollars per share)					$ 0.0001
Preferred Stock, Convertible, Conversion Price (in dollars per share)		$ 6.43	$ 6.43
Series C Convertible Preferred Stock [Member]
Temporary Equity, Shares Outstanding (in shares)		54,587	54,587		42,490
Temporary Equity, Par or Stated Value Per Share (in dollars per share)					$ 0.0001
Temporary Equity, Stock Issued During Period, Shares, New Issues (in shares)		10,500
Temporary Equity, Issued Price Per Share (in dollars per share)		$ 1,000	$ 1,000
Temporary Equity, Stock Issued During Period, Value, New Issues		$ 10.5
Temporary Equity, Stock Issued During Period, Shares Issued for Services (in shares)		210
Preferred Stock, Convertible, Conversion Price (in dollars per share)		$ 3.43	3.43
Convertible Preferred Stock [Member]
Temporary Equity, Issued Price Per Share (in dollars per share)		$ 1,000	$ 1,000
Temporary Stock, Threshold Trading Days for Conversion (Day)			60 days
Temporary Stock, Threshold Consecutive Trading Days for Conversion (Day)			90 days
Temporary Stock, Conversion Price Minimum Percentage			175.00%
Temporary Stock, Maximum Business Days Following FID Event for Conversion (Day)			10 days
Temporary Equity, Dividend Rate Percentage			12.00%
Dividends, Preferred Stock, Paid-in-kind			$ 5.7	$ 3.9
Convertible Preferred Stock [Member] | Subsequent Event [Member]
Dividends, Preferred Stock, Paid-in-kind	$ 5.7