Note 7 - Outstanding Stock Purchase Warrants (Details)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Outstanding at December 31, 2015 (in shares) | shares	56,442,157
Outstanding at December 31, 2015 (in dollars per share) | $ / shares	$ 0.14
Exercised (in shares) | shares	(3,664,588)
Exercised (in dollars per share) | $ / shares	$ 0.065
Outstanding at March 31, 2016 (in shares) | shares	52,777,569
Outstanding at March 31, 2016 (in dollars per share) | $ / shares	$ 0.14
Exercisable at March 31, 2016 (in shares) | shares	39,775,491
Exercisable at March 31, 2016 (in dollars per share) | $ / shares	$ 0.15