Note 9 - Options and Warrants to Purchase Common Stock - Summary of the Status of the Warrants Outstanding (Details)	9 Months Ended
	Sep. 30, 2016 $ / shares shares
Exercise Price 1 [Member]
Warrants Outstanding and Exercisable Number Outstanding (in shares) | shares	461,340
Warrants Outstanding and Exercisable Weighted Average Remaining Contractual Life	4 years 211 days
Warrants Outstanding and Exercisable Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 1.15
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	4 years 273 days
Warrants Outstanding and Exercisable Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0.25
Warrants Outstanding and Exercisable Number Outstanding (in shares) | shares	3,744,623
Warrants Outstanding and Exercisable Weighted Average Remaining Contractual Life	4 years 266 days
Warrants Outstanding and Exercisable Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0.36