Note 9 - Stockholders' Equity - Outstanding Common Stock Purchase Warrants (Details) - Purchase Warrants Expiring June 18, 2021 [Member]	Mar. 31, 2022 $ / shares shares
Warrants, number of common shares (in shares) | shares	1,391,667
Warrants, exercise price per share (in dollars per share) | $ / shares	$ 6.00