Note 6 - Term Loans and Convertible Promissory Notes - Convertible Promissory Notes (Details) - USD ($) $ in Millions |
Jun. 30, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Convertible note payable, due on March 29, 2019 | $ 5.5 | $ 4.5 |
| Convertible Note Payable, One [Member] | ||
| Convertible note payable, due on March 29, 2019 | 1.5 | |
| Convertible Note Payable Two [Member] | ||
| Convertible note payable, due on March 29, 2019 | 1.5 | |
| Convertible Note Payable, Three [Member] | ||
| Convertible note payable, due on March 29, 2019 | 1.5 | 1.5 |
| Convertible Note Payable, Four [Member] | ||
| Convertible note payable, due on March 29, 2019 | 1.5 | |
| Convertible Note Payable Five [Member] | ||
| Convertible note payable, due on March 29, 2019 | 2.0 | |
| Convertible Note Payable Six [Member] | ||
| Convertible note payable, due on March 29, 2019 | $ 0.5 |