Note 1 - General (Details Textual) - USD ($)		3 Months Ended
	Feb. 11, 2021	Mar. 31, 2021	Mar. 31, 2020
Class of Warrant or Right, Number of Warrants Issued (in shares)		2,850,000
Proceeds from Issuance of Private Placement		$ 25,812,000
Payments of Stock Issuance Costs		$ 1,783,000
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 182 days
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 182 days
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	$ 25,812,500
Payments of Stock Issuance Costs	$ 1,784,000