Note 3 - Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) |
Sep. 30, 2017 |
Dec. 31, 2016 |
---|---|---|
Fair value of liabilities | $ 2,785,863 | $ 3,921,917 |
Fair Value, Inputs, Level 1 [Member] | ||
Fair value of liabilities | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | ||
Fair value of liabilities | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | ||
Fair value of liabilities | 2,785,863 | 3,921,917 |
Stock Purchase Warrants [Member] | ||
Derivative instruments - stock purchase warrants | 2,785,863 | 3,921,917 |
Stock Purchase Warrants [Member] | Fair Value, Inputs, Level 1 [Member] | ||
Derivative instruments - stock purchase warrants | 0 | 0 |
Stock Purchase Warrants [Member] | Fair Value, Inputs, Level 2 [Member] | ||
Derivative instruments - stock purchase warrants | 0 | 0 |
Stock Purchase Warrants [Member] | Fair Value, Inputs, Level 3 [Member] | ||
Derivative instruments - stock purchase warrants | $ 2,785,863 | $ 3,921,917 |