Note 4 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.17	$ 5.16
Outstanding, Number of Shares (in shares)	68,400	72,400
Cancelled, Weighted Average Exercise Price (in dollars per share)	$ (5.30)	$ (4.96)
Cancelled (in shares)	(12,000)	(2,000)
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.27	$ 5.17
Outstanding, Number of Shares (in shares)	56,400	68,400
Outstanding, Weighted Average Remaining Contractual Term	4 years 171 days	5 years 255 days
Outstanding, Aggregate Intrinsic Value	$ 70,545	$ 83,933
Exercisable, Weighted Average Exercise Price (in dollars per share)			$ 6.27
Exercisable, Number of Shares (in shares)			56,400	68,400
Exercisable, Weighted Average Remaining Contractual Term	4 years 171 days	5 years 255 days
Exercisable, Aggregate Intrinsic Value			$ 70,545	$ 83,933
Exercised, Weighted Average Exercise Price (in dollars per share)		$ (4.96)
Exercised, Number of Shares (in shares)		(2,000)
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 5.17	$ 5.16	$ 6.27	$ 5.17