Note 9 - Shareholders' Equity - Summary of Unvested Restricted Common Shares (Details) - Restricted Stock [Member] - $ / shares |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2023 |
Dec. 31, 2022 |
|
| Unvested, number of shares (in shares) | 168,449 | 168,449 |
| Unvested, weighted-average grant-date fair value (in dollars per share) | $ 11.44 | $ 11.44 |
| Vested, number of shares (in shares) | 0 | 0 |
| Vested, weighted-average grant-date fair value (in dollars per share) | $ 0 | $ 0 |
| Unvested, number of shares (in shares) | 168,449 | 168,449 |
| Unvested, weighted-average grant-date fair value (in dollars per share) | $ 11.44 | $ 11.44 |