Consolidated Balance Sheets (Parentheticals) - $ / shares |
Dec. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 |
| Common stock, shares authorized (in shares) | 200,000,000 | 200,000,000 |
| Common stock, shares issued (in shares) | 136,819,647 | 98,812,008 |
| Common stock, shares outstanding (in shares) | 136,819,647 | 98,812,008 |