Note 7 - Financial Instruments (Details Textual) $ / shares in Units, shares in Millions	Mar. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Sep. 02, 2016 USD ($) $ / shares shares
Warrants and Rights Outstanding | $	$ 6,132,947	$ 6,116,882
The 2016 Warrant [Member]
Class of Warrant or Right Outstanding, Common Stock Value Used to Determine Number of Shares Called | $			$ 4,000,000
Class of Warrant or Right Outstanding, Common Stock Price Per Share Used to Determine Number of Shares Called (in dollars per share) | $ / shares			$ 2.29
Warrants and Rights Outstanding, Term (Year)			10 years
Class of Warrant or Right, Subscription Price of Warrants or Rights (in dollars per share) | $ / shares			$ 1.50
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares			$ 1.50
Class of Warrant or Right, Outstanding (in shares) | shares	1.5		2.7
Warrants and Rights Outstanding | $	$ 6,100,000
The 2016 Warrant [Member] | Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input	0.5
The 2016 Warrant [Member] | Measurement Input, Expected Dividend Rate [Member]
Warrants and Rights Outstanding, Measurement Input	0
The 2016 Warrant [Member] | Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input	6.42
The 2016 Warrant [Member] | Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input	75