Note 7 - Warrants and Registration Rights Agreements - Summary of the Warrants Issued and Changes (Details) - $ / shares |
12 Months Ended | |
|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Outstanding, beginning balance (in shares) | 20,140,731 | 15,855,017 |
| Outstanding, weighted average exercise price (in dollars per share) | $ 0.15 | $ 0.18 |
| Granted (in shares) | 500,000 | 5,000,000 |
| Granted, weighted average exercise price (in dollars per share) | $ 0.76 | $ 0.09 |
| Canceled / Expired (in shares) | (8,829,082) | (714,286) |
| Canceled / expired, weighted average exercise price (in dollars per share) | $ 0.14 | $ 0.53 |
| Exercised (in shares) | ||
| Exercised, weighted average exercise price (in dollars per share) | ||
| Outstanding, ending balance (in shares) | 11,811,649 | 20,140,731 |
| Outstanding, weighted average exercise price (in dollars per share) | $ 0.14 | $ 0.15 |