Note 8 - Earnings (Loss) Per Share - Reconciliation of the Amounts Used in Calculating Basic and Diluted Net Loss per Common Share (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income (loss) available to common shareholders	$ 270,815	$ (126,339)
Income (loss) available to common shareholders, shares (in shares)	11,282,671	11,211,760
Income (loss) available to common shareholders, per share amount (in dollars per share)	$ 0.02	$ (0.01)
Effect of dilutive stock options, shares (in shares)	1,003,545
Diluted net loss per common share	$ 270,815	$ (126,339)
Diluted net loss per common share, shares (in shares)	12,286,216	11,211,760
Diluted net loss per common share, per share amount (in dollars per share)	$ 0.02	$ (0.01)