Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - 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, 2018	$ 690,200	$ 51,382,585	$ (36,971,124)	$ 65,829,687	$ (452,756)	$ 80,478,592
Net income	0	0	0	2,120,364	0	2,120,364
Other comprehensive income (loss)	0	0	0	0	380,791	380,791
Dividends on common stock	0	0	0	(582,817)	0	(582,817)
Stock award plans	0	(53,689)	222,789	0	0	169,100
Net income	0	0	0	2,120,364	0	2,120,364
Stock award plans	0	(53,689)	222,789	0	0	169,100
Stock options exercised	1,000	50,900	0	0	0	51,900
Balance at Mar. 31, 2019	691,200	51,379,796	(36,748,335)	67,367,234	(71,965)	82,617,930
Balance at Dec. 31, 2018	690,200	51,382,585	(36,971,124)	65,829,687	(452,756)	80,478,592
Net income						4,548,863
Other comprehensive income (loss)						(223,469)
Net income						4,548,863
Balance at Jun. 30, 2019	691,200	51,575,395	(37,066,810)	69,214,712	(676,225)	83,738,272
Balance at Mar. 31, 2019	691,200	51,379,796	(36,748,335)	67,367,234	(71,965)	82,617,930
Net income	0	0	0	2,428,499	0	2,428,499
Other comprehensive income (loss)	0	0	0	0	(604,260)	(604,260)
Dividends on common stock	0	0	0	(581,021)	0	(581,021)
Treasury stock purchased	0	0	(312,892)	0	0	(312,892)
Stock award plans	0	195,599	(5,583)	0	0	190,016
Net income	0	0	0	2,428,499	0	2,428,499
Stock award plans	0	195,599	(5,583)	0	0	190,016
Stock options exercised	0	0	0	0	0	0
Treasury stock purchased	0	0	(312,892)	0	0	(312,892)
Balance at Jun. 30, 2019	691,200	51,575,395	(37,066,810)	69,214,712	(676,225)	83,738,272
Net income	0	0	0	2,550,542	0	2,550,542
Other comprehensive income (loss)	0	0	0	0	(24,711)	(24,711)
Dividends on common stock	0	0	0	(569,784)	0	(569,784)
Treasury stock purchased	0	0	(2,151,696)	0	0	(2,151,696)
Stock award plans	0	187,157	(24,950)	0	0	162,207
Net income	0	0	0	2,550,542	0	2,550,542
Stock award plans	0	187,157	(24,950)	0	0	162,207
Stock options exercised	400	19,920	0	0	0	20,320
Treasury stock purchased	0	0	(2,151,696)	0	0	(2,151,696)
Balance at Sep. 30, 2019	691,600	51,782,472	(39,243,456)	71,195,470	(700,936)	83,725,150
Net income	0	0	0	2,315,685	0	2,315,685
Other comprehensive income (loss)	0	0	0	0	269,901	269,901
Dividends on common stock	0	0	0	(650,405)	0	(650,405)
Treasury stock purchased	0	0	(1,140,291)	0	0	(1,140,291)
Stock award plans	0	108,965	(14,903)	0	0	94,062
Net income	0	0	0	2,315,685	0	2,315,685
Stock award plans	0	108,965	(14,903)	0	0	94,062
Stock options exercised	350	17,430	0	0	0	17,780
Treasury stock purchased	0	0	(1,140,291)	0	0	(1,140,291)
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	2,104,845	0	2,104,845
Other comprehensive income (loss)	0	0	0	0	(1,985,859)	(1,985,859)
Dividends on common stock	0	0	0	(654,735)	0	(654,735)
Treasury stock purchased	0	0	(390,268)	0	0	(390,268)
Stock award plans	0	(636,438)	693,787	0	0	57,349
Net income	0	0	0	2,104,845	0	2,104,845
Stock award plans	0	(636,438)	693,787	0	0	57,349
Treasury stock purchased	0	0	(390,268)	0	0	(390,268)
Balance at Mar. 31, 2020	691,950	51,272,429	(40,095,131)	74,310,860	(2,416,894)	83,763,214
Balance at Dec. 31, 2019	691,950	51,908,867	(40,398,650)	72,860,750	(431,035)	84,631,882
Net income						3,988,228
Other comprehensive income (loss)						(1,139,423)
Net income						3,988,228
Balance at Jun. 30, 2020	691,950	51,188,585	(40,068,788)	75,539,116	(1,570,458)	85,780,405
Balance at Mar. 31, 2020	691,950	51,272,429	(40,095,131)	74,310,860	(2,416,894)	83,763,214
Net income	0	0	0	1,883,383	0	1,883,383
Other comprehensive income (loss)	0	0	0	0	846,436	846,436
Dividends on common stock	0	0	0	(655,127)	0	(655,127)
Stock award plans	0	(83,844)	26,343	0	0	(57,501)
Net income	0	0	0	1,883,383	0	1,883,383
Stock award plans	0	(83,844)	26,343	0	0	(57,501)
Balance at Jun. 30, 2020	$ 691,950	$ 51,188,585	$ (40,068,788)	$ 75,539,116	$ (1,570,458)	$ 85,780,405