Note 12 - Stockholders' Equity - Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Options Outstanding (in shares) | shares	2,256,000
Weighted Average Remaining Contractual Term (Year)	9 years 18 days
Weighted Average Exercise Price (in dollars per share)	$ 0.83
Option Exercisabl (in shares) | shares	1,327,667
Weighted Average Exercise Price of Options Exercisable (in dollars per share)	$ 0.89
Exercise Price Range 1 [Member]
Exercise Price, Lower Limit (in dollars per share)	0.65
Exercise Price, Upper Limit (in dollars per share)	$ 0.70
Options Outstanding (in shares) | shares	1,865,000
Weighted Average Remaining Contractual Term (Year)	9 years 277 days
Weighted Average Exercise Price (in dollars per share)	$ 0.67
Option Exercisabl (in shares) | shares	996,667
Weighted Average Exercise Price of Options Exercisable (in dollars per share)	$ 0.66
Exercise Price Range 2 [Member]
Exercise Price, Lower Limit (in dollars per share)	1.10
Exercise Price, Upper Limit (in dollars per share)	$ 1.32
Options Outstanding (in shares) | shares	25,000
Weighted Average Remaining Contractual Term (Year)	6 years 306 days
Weighted Average Exercise Price (in dollars per share)	$ 1.28
Option Exercisabl (in shares) | shares	15,000
Weighted Average Exercise Price of Options Exercisable (in dollars per share)	$ 1.25
Exercise Price Range 3 [Member]
Exercise Price, Lower Limit (in dollars per share)	1.51
Exercise Price, Upper Limit (in dollars per share)	$ 1.69
Options Outstanding (in shares) | shares	366,000
Weighted Average Remaining Contractual Term (Year)	5 years 208 days
Weighted Average Exercise Price (in dollars per share)	$ 1.60
Option Exercisabl (in shares) | shares	316,000
Weighted Average Exercise Price of Options Exercisable (in dollars per share)	$ 1.59