Note 10 - Income Per Common Share - Income Per Share (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic Income per Common Share	$ 2,216,016	$ 2,104,845
Basic Income per Common Share (in shares)	4,337,870	4,309,441
Basic Income per Common Share (in dollars per share)	$ 0.51	$ 0.49
Effect of Dilutive Securities, Average Common Shares Outstanding (in shares)	12,226	26,861
Diluted Income per Common Share	$ 2,216,016	$ 2,104,845
Diluted Income per Common Share (in shares)	4,350,096	4,336,302
Diluted Income per Common Share (in dollars per share)	$ 0.51	$ 0.49