Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 31, 2017	$ 687,850	$ 50,856,069	$ (37,125,541)	$ 60,679,308	$ (206,193)	$ 74,891,493
Net income	0	0	0	7,331,879	0	7,331,879
Other comprehensive income (loss)	0	0	0	0	(246,563)	(246,563)
Dividends on common stock	0	0	0	(2,181,500)	0	(2,181,500)
Stock award plans	0	362,636	154,417	0	0	517,053
Stock options exercised	2,350	163,880	0	0	0	166,230
Balance at Dec. 31, 2018	690,200	51,382,585	(36,971,124)	65,829,687	(452,756)	80,478,592
Net income	0	0	0	9,415,090	0	9,415,090
Other comprehensive income (loss)	0	0	0	0	21,721	21,721
Dividends on common stock	0	0	0	(2,384,027)	0	(2,384,027)
Stock award plans	0	438,032	177,353	0	0	615,385
Stock options exercised	1,750	88,250	0	0	0	90,000
Treasury stock purchased	0	0	(3,604,879)	0	0	(3,604,879)
Balance at Dec. 31, 2019	691,950	51,908,867	(40,398,650)	72,860,750	(431,035)	84,631,882
Net income	0	0	0	6,832,214	0	6,832,214
Other comprehensive income (loss)	0	0	0	0	377,657	377,657
Dividends on common stock	0	0	0	(2,619,257)	0	(2,619,257)
Stock award plans	0	(571,648)	707,786	0	0	136,138
Treasury stock purchased	0	0	(390,268)	0	0	(390,268)
Balance at Dec. 31, 2020	$ 691,950	$ 51,337,219	$ (40,081,132)	$ 77,073,707	$ (53,378)	$ 88,968,366