Note 6 - Income Per Common Share - Income Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effect of Dilutive Securities (in shares)	51,686	53,977	54,439	52,028
Effect of Dilutive Securities (in shares)	51,686	53,977	54,439	52,028
Diluted Income Per Common Share	$ 1,592,573	$ 1,256,152	$ 3,021,814	$ 2,532,757
Diluted Income Per Common Share (in shares)	4,426,411	4,420,484	4,423,360	4,415,403
Diluted Income Per Common Share (in dollars per share)	$ 0.36	$ 0.28	$ 0.68	$ 0.57
Basic Income Per Common Share	$ 1,592,573	$ 1,256,152	$ 3,021,814	$ 2,532,757
Basic Income Per Common Share (in shares)	4,374,725	4,366,507	4,368,921	4,363,375
Basic Income Per Common Share (in dollars per share)	$ 0.36	$ 0.29	$ 0.69	$ 0.58