Note 5 - Loss Per Share - Shares Used in Basic and Diluted Loss Per Common Share Computations (Details) - USD ($)		3 Months Ended		12 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Net loss available in basic and diluted calculation		$ (1,760,022)	$ (1,341,847)	$ (7,746,593)
Unrealized gain from marketable securities				$ (1,501)
Comprehensive (loss)		$ (1,760,022)	$ (1,341,847)
Weighted average common shares outstanding-basic (in shares)		11,383,217	6,450,967
Effect of diluted stock options, warrants and preferred stock (1) (in shares)	[1]
Loss per common share - basic and diluted (in dollars per share)		$ (0.15)	$ (0.21)

[1] The number of shares underlying options and warrants outstanding as of March 31, 2018 and March 31, 2017 are 5,950,631 and 1,427,558 respectively. The number of shares underlying the preferred stock as of March 31, 2018 is 79,246. The effect of the shares that would be issued upon exercise of such options, warrants and preferred stock has been excluded from the calculation of diluted loss per share because those shares are anti-dilutive.