Note 11 - Subsequent Event (Details Textual) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 17, 2020	Dec. 31, 2019	Dec. 31, 2018
Proceeds from Warrant Exercises		$ 3,888,425
Subsequent Event [Member]
Class of Warrant or Right, Exercised	1,124,071
Class of Warrant or Right, Exercised During Period, Exercise Price	$ 0.35
Proceeds from Warrant Exercises	$ 400,000