Note 1 - General (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended
	Feb. 11, 2021	Jun. 30, 2021	Jun. 30, 2020
Class of Warrant or Right, Number of Warrants Issued (in shares)		2,850,000
Proceeds from Issuance of Private Placement		$ 25,812	$ 0
Payments of Stock Issuance Costs		$ 1,783	$ (0)
Warrants Issued in Connection with Private Placement [Member]
Class of Warrant or Right, Number of Warrants Issued (in shares)	2,500,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	2,500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 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)	350,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 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)	5,000,000
Shares Issued, Price Per Share (in dollars per share)	$ 5.1625
Proceeds from Issuance of Private Placement	$ 25,812
Payments of Stock Issuance Costs	$ 1,783