Note 11 - Subsequent Events (Details Textual) - USD ($) |
Jan. 19, 2022 |
Feb. 11, 2021 |
Sep. 29, 2020 |
|---|---|---|---|
| Stock Issued During Period, Shares, New Issues (in shares) | 1,644,000 | ||
| Proceeds from Issuance or Sale of Equity, Total | $ 11,200,000 | ||
| Subsequent Event [Member] | Pre-Funded Warrants [Member] | |||
| Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | 2,360,000 | ||
| Subsequent Event [Member] | Warrants Issued in Private Placement [Member] | |||
| Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) | 3,067,484 | ||
| Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ 3.26 | ||
| Warrants and Rights Outstanding, Term (Year) | 5 years | ||
| Subsequent Event [Member] | Private Placement [Member] | |||
| Stock Issued During Period, Shares, New Issues (in shares) | 707,484 | ||
| Proceeds from Issuance or Sale of Equity, Total | $ 9,200,000 |