Note 5 - Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Stock Option [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	16,933	23,442	17,279	27,036
Restricted Stock [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	966		762
Net income	$ 1,000,350	$ 1,111,344	$ 4,342,262	$ 4,063,647
Numerator for basic and diluted earnings per share	$ 1,000,350	$ 1,111,344	$ 4,342,262	$ 4,063,647
Weighted-average shares outstanding-basic (in shares)	9,188,483	10,175,650	9,341,364	10,199,841
Effect of dilutive securities (in shares)	17,899	23,442	18,041	27,036
Denominator for diluted earnings per share-weighted-average shares (in shares)	9,206,382	10,199,092	9,359,405	10,226,877
Basic earnings per share (in dollars per share)	$ 0.11	$ 0.11	$ 0.46	$ 0.40
Diluted earnings per share (in dollars per share)	$ 0.11	$ 0.11	$ 0.46	$ 0.40