Note 9 - Warrants (Details Textual) $ / shares in Units, $ in Thousands		6 Months Ended
	Feb. 11, 2021 USD ($) $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)
Class of Warrant or Right, Number of Warrants Issued (in shares) | shares		2,850,000
Proceeds from Issuance of Private Placement | $		$ 25,812	$ 0
Payments of Stock Issuance Costs | $		$ 1,783	$ (0)
Warrants and Rights Outstanding | $	$ 7,337
Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input	0.0059
Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input	0.9466
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input	5.5
Warrants Issued in Connection with Private Placement [Member]
Class of Warrant or Right, Number of Warrants Issued (in shares) | shares	2,500,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares	2,500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 5.10	$ 5.10
Warrants and Rights Outstanding, Term (Year)	5 years 6 months
The Placement Agent Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | shares	350,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 6.45	$ 6.45
Warrants and Rights Outstanding, Term (Year)	5 years 6 months
Private Placement [Member]
Stock Issued During Period, Shares, New Issues (in shares) | shares	5,000,000
Shares Issued, Price Per Share (in dollars per share) | $ / shares	$ 5.1625
Proceeds from Issuance of Private Placement | $	$ 25,812
Payments of Stock Issuance Costs | $	$ 1,783