Note 10 - Preferred Stock and Common Stock Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended			12 Months Ended
	Jan. 15, 2021	May 31, 2019	Sep. 30, 2018	Aug. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Gain (Loss) on Revaluation of Warrants					$ 7,870	$ (2,657)
Series A Warrants [Member]
Exercise of Warrants, Percent of Fully Diluted Common Stock Acquirable					0.71%
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 0.01
Series B Warrants [Member]
Exercise of Warrants, Percent of Fully Diluted Common Stock Acquirable					0.71%
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)					$ 0.01
Common Stock Warrants [Member]
Warrants and Rights Outstanding, Term (Year)					3 years
Exercise of Warrants, Threshold Trading Days (Day)					60 days
Exercise of Warrants, Threshold Consecutive Trading Days (Day)					90 days
Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)						10,094,000
Common Stock [Member] | Backstop Agreements [Member]
Stock Issued During Period, Shares, New Issues (in shares)				413,658
Series A Convertible Preferred Stock [Member]
Temporary Equity, Stock Issued During Period, Shares, New Issues (in shares)				50,000
Temporary Equity, Par or Stated Value Per Share (in dollars per share)				$ 0.0001
Temporary Equity, Issued Price Per Share (in dollars per share)				$ 1,000
Temporary Equity, Stock Issued During Period, Value, New Issues				$ 50,000
Temporary Equity, Stock Issued During Period, Shares Issued for Services (in shares)				1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share)					$ 7.50
Accretion of Discount Amount					$ 2,500
Series A Convertible Preferred Stock [Member] | Fund Purchasers [Member]
Preferred Stock, Convertible, Conversion Price (in dollars per share)					$ 5.58
Series A Convertible Preferred Stock [Member] | HGC [Member]
Preferred Stock, Convertible, Conversion Price (in dollars per share)					6.24
Series B Convertible Preferred Stock [Member]
Temporary Equity, Stock Issued During Period, Shares, New Issues (in shares)		20,945	29,055
Temporary Equity, Par or Stated Value Per Share (in dollars per share)			$ 0.0001
Temporary Equity, Issued Price Per Share (in dollars per share)		$ 1,000	$ 1,000
Temporary Equity, Stock Issued During Period, Value, New Issues		$ 20,945	$ 29,055
Temporary Equity, Stock Issued During Period, Shares Issued for Services (in shares)		418	581
Convertible Preferred Stock [Member]
Temporary Equity, Issued Price Per Share (in dollars per share)					1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share)					$ 7.34
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					$ 14,300	$ 11,200
Convertible Preferred Stock [Member] | Subsequent Event [Member]
Dividends, Preferred Stock, Paid-in-kind	$ 3,900