Note 3 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.17	$ 5.04	$ 5.16	$ 5.04
Outstanding, Number of Shares (in shares)	72,400	84,600
Outstanding, Number of Shares (in shares)	70,400	84,600
Outstanding, Weighted Average Remaining Contractual Term	5 years 302 days	6 years 171 days
Outstanding, Aggregate Intrinsic Value	$ 86,886	$ 104,656
Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.17	$ 5.04
Exercisable, Number of Shares (in shares)	70,400	84,600
Exercisable, Weighted Average Remaining Contractual Term	5 years 302 days	6 years 171 days
Exercisable, Aggregate Intrinsic Value	$ 86,886	$ 104,656
Exercised, Weighted Average Exercise Price (in dollars per share)	$ (4.96)
Exercised (in shares)	(2,000)