Note 8 - Stockholders' Equity - Computation of Comprehensive Earnings (Loss) Per Share (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Net income	$ 1,610,954	$ 29,410	$ 1,714,155	$ 183,061	$ 636,814
Weighted average shares outstanding - basic (in shares)	2,191,689	2,191,689	2,191,689	2,191,689
Effect of dilutive potential shares (in shares)	175,000	0	175,000	0
Shares outstanding - diluted (in shares)	2,366,689	2,191,689	2,366,689	2,191,689
Net comprehensive income per share - basic (in dollars per share)	$ 0.74	$ 0.01	$ 0.78	$ 0.08
Net comprehensive income per share - diluted (in dollars per share)	$ 0.68	$ 0.01	$ 0.72	$ 0.08