Note 4 - Stock-based Compensation - Summary of Stock Options (Details)	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares
Shares outstanding (in shares) | shares	304,500
Shares outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 2.06
Shares outstanding, weighted average remaining contractual life	5 years 182 days
Shares outstanding, aggregate intrinsic value | $	$ 495,300
Shares vested and exercisable (in shares) | shares	256,500
Shares vested and exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 1.76
Shares vested and exercisable, weighted average remaining contractual life	4 years 255 days
Shares vested and exercisable, aggregate intrinsic value | $	$ 489,240