Note 4 - Loss Per Share - Shares Used in Basic and Diluted Loss Per Common Share Computations (Details) - USD ($)		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Net loss available in basic and diluted calculation		$ (2,543,670)	$ (2,561,281)	$ (3,885,517)	$ (4,737,650)	$ (6,526,014)
Unrealized gain from marketable securities			3,028		5,878	$ 1,501
Comprehensive (loss)		$ (2,543,670)	$ (2,558,253)	$ (3,885,517)	$ (4,731,772)
Effect of diluted stock options, warrants and preferred stock (1) (in shares)	[1]
Weighted average common shares outstanding-basic (in shares)		6,167,689	2,695,203	6,308,554	1,709,526
Loss per common share - basic and diluted (in dollars per share)		$ (0.41)	$ (0.95)	$ (0.62)	$ (2.77)

[1] The number of shares underlying options and warrants outstanding as of June 30, 2017 and June 30, 2016 are 3,850,878 and 398,775 respectively. The number of shares underlying the preferred stock as of June 30, 2017 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.