Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)		Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class C [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Treasury Stock, Common [Member]	Total
Balance at Dec. 31, 2021		$ 35,285,444	$ 5,733,130	$ 57,985,947	$ 18,070,448	$ 184,537,489	$ (1,845,624)	$ 299,766,834
Net earnings (loss)						3,228,718		3,228,718
Other comprehensive income (loss)					(12,190,330)			(12,190,330)
Stock-based compensation expense				271,747				271,747
Exercise of stock options		100,446		(8,487)				91,959
Sale of treasury stock				24,055			1,880,125	1,904,180
Purchase of treasury stock				106,176			(878,417)	(772,241)
Conversion Class C to Class A		414	(414)
Balance at Mar. 31, 2022		35,386,304	5,732,716	58,379,438	5,880,118	187,766,207	(843,916)	292,300,867
Balance at Dec. 31, 2021		35,285,444	5,733,130	57,985,947	18,070,448	184,537,489	(1,845,624)	299,766,834
Net earnings (loss)								4,449,982
Balance at Sep. 30, 2022		37,435,080	5,779,718	64,840,595	(15,071,680)	180,919,986	(5,041,822)	268,861,877
Balance at Mar. 31, 2022		35,386,304	5,732,716	58,379,438	5,880,118	187,766,207	(843,916)	292,300,867
Net earnings (loss)						3,574,449		3,574,449
Other comprehensive income (loss)					(10,310,485)			(10,310,485)
Stock-based compensation expense				220,175				220,175
Exercise of stock options		37,746		(2,440)				35,306
Sale of treasury stock				50,401			1,119,392	1,169,793
Purchase of treasury stock							(6,505,050)	(6,505,050)
Conversion Class C to Class A		154,218	(154,218)
Stock dividends		1,779,108	278,924	6,009,453		(8,067,485)
Balance at Jun. 30, 2022		37,357,376	5,857,422	64,657,027	(4,430,367)	183,273,171	(6,229,574)	280,485,055
Net earnings (loss)						(2,353,185)		(2,353,185)
Other comprehensive income (loss)					(10,641,313)			(10,641,313)
Stock-based compensation expense				230,853				230,853
Sale of treasury stock				(47,285)			1,187,752	1,140,467
Conversion Class C to Class A		77,704	(77,704)
Balance at Sep. 30, 2022		37,435,080	5,779,718	64,840,595	(15,071,680)	180,919,986	(5,041,822)	268,861,877
Balance at Dec. 31, 2022		37,516,062	5,779,718	64,767,769	(13,070,277)	202,160,306	(4,366,651)	292,786,927
Cumulative effect adjustment upon adoption of new accounting standard (ASU 2016-13)						(671,506)		(671,506)
Net earnings (loss)						1,240,172		1,240,172
Other comprehensive income (loss)					4,127,558			4,127,558
Stock-based compensation expense				143,671				143,671
Exercise of stock options		96,092		(62,073)				34,019
Sale of treasury stock				(43,493)			620,651	577,158
Purchase of treasury stock							(1,204,357)	(1,204,357)
Conversion Class C to Class A		1,872	(1,872)
Balance at Mar. 31, 2023		37,614,026	5,777,846	64,805,874	(8,942,719)	202,728,972	(4,950,357)	297,033,642
Balance at Dec. 31, 2022		37,516,062	5,779,718	64,767,769	(13,070,277)	202,160,306	(4,366,651)	292,786,927
Cumulative effect adjustment upon adoption of new accounting standard (ASU 2016-13)	[1]							665,030
Net earnings (loss)								11,634,171
Balance at Sep. 30, 2023		40,015,222	5,943,708	72,190,361	(18,282,298)	204,117,486	(6,090,935)	297,893,544
Balance at Mar. 31, 2023		37,614,026	5,777,846	64,805,874	(8,942,719)	202,728,972	(4,950,357)	297,033,642
Net earnings (loss)						6,352,706		6,352,706
Other comprehensive income (loss)					(3,952,052)			(3,952,052)
Stock-based compensation expense				141,954				141,954
Exercise of stock options		159,284		(154,424)				4,860
Sale of treasury stock				(54,350)			623,056	568,706
Purchase of treasury stock				126,990			(1,514,049)	(1,387,059)
Conversion Class C to Class A		113,930	(113,930)
Vesting of restricted stock units		810		(810)
Stock dividends		1,899,350	283,188	6,820,431		(9,002,969)
Balance at Jun. 30, 2023		39,787,400	5,947,104	71,685,665	(12,894,771)	200,078,709	(5,841,350)	298,762,757
Net earnings (loss)						4,041,293		4,041,293
Other comprehensive income (loss)					(5,387,527)			(5,387,527)
Stock-based compensation expense				145,973				145,973
Exercise of stock options		223,006		(196,926)				26,080
Sale of treasury stock				98,387			458,530	556,917
Purchase of treasury stock				456,166			(708,115)	(251,949)
Conversion Class C to Class A		3,396	(3,396)
Vesting of restricted stock units		810		(810)
Stock dividends		610		1,906		(2,516)
Balance at Sep. 30, 2023		$ 40,015,222	$ 5,943,708	$ 72,190,361	$ (18,282,298)	$ 204,117,486	$ (6,090,935)	$ 297,893,544

[1] See Note 2 of the notes to the condensed consolidated financial statements