Note 5 - Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 1,231,265	$ 1,520,997
Numerator for basic and diluted earnings per share	$ 1,231,265	$ 1,520,997
Denominator for basic earnings per share – weighted-average shares (in shares)	9,308,726	9,698,951
Effect of dilutive securities:
Effect of dilutive securities (in shares)	22,193	19,502
Denominator for diluted earnings per share – weighted-average shares (in shares)	9,330,919	9,718,453
Basic earnings per share (in dollars per share)	$ 0.13	$ 0.16
Diluted earnings per share (in dollars per share)	$ 0.13	$ 0.16
Employee Stock Option [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	19,729	19,461
Restricted Stock [Member]
Effect of dilutive securities:
Effect of dilutive securities (in shares)	2,464	41