Note 7 - Options and Warrants to Purchase Common Stock - Summary of the Status of the Warrants Outstanding (Details)	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Warrants Outstanding and Exercisable Number Outstanding (in shares) | shares	10,000,873
Warrants Outstanding and Exercisable Weighted Average Remaining Contractual Life (Year)	4 years 175 days
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 0.36
Exercise Price 1 [Member]
Warrants Outstanding and Exercisable Number Outstanding (in shares) | shares	6,256,250
Warrants Outstanding and Exercisable Weighted Average Remaining Contractual Life (Year)	4 years 335 days
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 0.04
Exercise Price 2 [Member]
Warrants Outstanding and Exercisable Number Outstanding (in shares) | shares	3,283,283
Warrants Outstanding and Exercisable Weighted Average Remaining Contractual Life (Year)	3 years 273 days
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 0.25
Exercise Price 3 [Member]
Warrants Outstanding and Exercisable Number Outstanding (in shares) | shares	461,340
Warrants Outstanding and Exercisable Weighted Average Remaining Contractual Life (Year)	3 years 211 days
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 1.15