Note 10 - Income Per Common Share - Income Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic Income Per Common Share	$ 2,550,542	$ 3,934,242	$ 7,099,405	$ 4,947,003
Weighted average common shares outstanding, basic (in shares)	4,396,241	4,418,196	4,429,066	4,406,830
Basic Income Per Common Share (in dollars per share)	$ 0.58	$ 0.89	$ 1.60	$ 1.12
Effect of Dilutive Securities, Average Common Shares Outstanding (in shares)	58,091	72,389	56,532	72,058
Diluted Income Per Common Share	$ 2,550,542	$ 3,934,242	$ 7,099,405	$ 4,947,003
Weighted average common shares outstanding, diluted (in shares)	4,454,332	4,490,585	4,485,598	4,478,888
Diluted Income Per Common Share (in dollars per share)	$ 0.57	$ 0.88	$ 1.58	$ 1.10