Note 9 - Warrants - Summary of Warrants Outstanding and Exercisable (Details) - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Number outstanding/ exercisable (in shares)	2,850,000	2,850,000
Warrants Issued in Connection with Private Placement [Member]
Number outstanding/ exercisable (in shares)	2,500,000
Weighted average remaining life (Year)	4 years 4 months 13 days
Weighted average exercise price (in dollars per share)	$ 5.10
The Placement Agent Warrants [Member]
Number outstanding/ exercisable (in shares)	350,000
Weighted average remaining life (Year)	4 years 4 months 13 days
Weighted average exercise price (in dollars per share)	$ 6.45