Note 3 - Fair Value Measurements - Summary of Unobservable Inputs in Fair Value Measurements (Details)	Dec. 31, 2019 USD ($)	Dec. 31, 2018
Measurement Input, Expected Term [Member] | Minimum [Member]
Warrants and Rights Outstanding, Measurement Input	0.0104	0.0004
Measurement Input, Expected Term [Member] | Maximum [Member]
Warrants and Rights Outstanding, Measurement Input	0.016	0.026
Fair Value, Inputs, Level 3 [Member]
Fair value	$ 6,414
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Expected Term [Member] | Minimum [Member]
Warrants and Rights Outstanding, Measurement Input	1.04
Fair Value, Inputs, Level 3 [Member] | Measurement Input, Expected Term [Member] | Maximum [Member]
Warrants and Rights Outstanding, Measurement Input	1.6