Note 5 - Stockholders' Equity and Common Stock Warrants (Details Textual) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Deemed Dividend From Warrant Exchange		$ 1,950,378		$ 1,950,378
Class of Warrant or Rights, Expired (in shares)				0
Class of Warrant or Right, Exercised During Period (in shares)				19,089,361
Stock Issued During Period, Shares, Exercise Of Warrants (in shares)				19,089,361
Proceeds From Warrant Exercises, Net				$ 7,800,000
The May 2020 Offering Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	571,429
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 1.3125	$ 1.3125		$ 1.3125
Warrants and Rights Outstanding, Term (Year)	5 years
Prior Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	5,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 0.35
Class of Warrant or Right, Exchange, Additional Consideration Per Share (in dollars per share)	$ 0.125
New Warrants Issued May 8, 2020 [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	5,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 0.5263
The May 2020 PA Warrants [Member] | H.C Wainwright & Co., LLC [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	250,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 0.5938
The May 2020 Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)	11,428,572
Shares Issued, Price Per Share (in dollars per share)	$ 1.05
Proceeds from Issuance of Common Stock	$ 10,300,000