Note 4 - Investment Unit (Details Textual) - USD ($)			1 Months Ended	12 Months Ended
	Apr. 03, 2018	Mar. 12, 2014	Dec. 31, 2013	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)				$ 4.37	$ 1.45	$ 2.36
Stock Issued During Period, Shares, New Issues (in shares)				5,511,599
Fair Value Adjustment of Warrants			$ 2,500,000	$ 0
Conversion of Preferred Stock to Common Stock [Member]
Conversion of Stock, Shares Issued (in shares)	1,235,219			9,324,177
Series B Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)		184,797
Warrant Issued to TETF [Member]
Class of Warrant or Right, Purchase Percentage					80.00%
Warrant Discount Rate					20.00%
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 0.001			$ 0.001
Promissory Note [Member]
Contingent Debt					$ 4,500,000
Contingent Debt, Interest Rate					8.00%