Consolidated Balance Sheets (Parentheticals) - $ / shares |
Dec. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Preferred stock, shares authorized (in shares) | 5,000,000 | 5,000,000 |
| Preferred stock, par value (in dollars per share) | $ 0.0001 | $ 0.0001 |
| Preferred stock, shares issued (in shares) | 0 | 0 |
| Preferred stock, shares outstanding (in shares) | 0 | 0 |
| Common stock, shares authorized (in shares) | 150,000,000 | 150,000,000 |
| Common stock, par value (in dollars per share) | $ 0.0001 | $ 0.0001 |
| Common stock, shares issued (in shares) | 40,851,945 | 37,554,162 |
| Common stock, shares outstanding (in shares) | 40,851,945 | 37,554,162 |