Note 11 - Stockholders' Equity - Outstanding Common Stock Purchase Warrants (Details) - Purchase Warrants Expiring June 18, 2021 [Member] |
Dec. 31, 2021
$ / shares
shares
|
|---|---|
| Warrants, number of common shares (in shares) | shares | 1,391,667 |
| Warrants, exercise price (in dollars per share) | $ / shares | $ 6.00 |