Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member] Class A Common Stock [Member]	Common Stock [Member] Class B Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Beginning balance at Dec. 31, 2018	$ 258,194	$ 56,492	$ 261,258,423	$ (14,228,059)	$ 192,751,208	$ (41,226,357)	$ 398,869,901
Beginning balance (in shares) at Dec. 31, 2018	25,819,341	5,649,240
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (stock compensation plans)	$ 1,671		2,225,527				2,227,198
Issuance of common stock (stock compensation plans) (in shares)	167,096
Stock-based compensation	$ 2,175		4,251,665				4,253,840
Stock-based compensation (in shares)	217,498
Net income					47,151,744		47,151,744
Cash dividends					(16,219,393)		(16,219,393)
Grant of stock options			415,986		(415,986)		0
Other comprehensive income (loss)				14,732,229			14,732,229
Ending balance at Dec. 31, 2019	$ 262,040	$ 56,492	268,151,601	504,170	223,267,573	(41,226,357)	451,015,519
Ending balance (in shares) at Dec. 31, 2019	26,203,935	5,649,240
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (stock compensation plans)	$ 1,532		2,057,504				2,059,036
Issuance of common stock (stock compensation plans) (in shares)	153,233
Stock-based compensation	$ 12,946		18,582,085				18,595,031
Stock-based compensation (in shares)	1,294,606
Net income					52,815,252		52,815,252
Cash dividends					(17,337,160)		(17,337,160)
Grant of stock options			358,377		(358,377)		0
Other comprehensive income (loss)				10,626,442			10,626,442
Ending balance at Dec. 31, 2020	$ 276,518	$ 56,492	289,149,567	11,130,612	258,387,288	(41,226,357)	517,774,120
Ending balance (in shares) at Dec. 31, 2020	27,651,774	5,649,240
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (stock compensation plans)	$ 1,578		2,161,142				2,162,720
Issuance of common stock (stock compensation plans) (in shares)	157,783
Stock-based compensation	$ 9,466		13,260,855				13,270,321
Stock-based compensation (in shares)	946,646
Net income					25,254,174		25,254,174
Cash dividends					(19,578,187)		(19,578,187)
Grant of stock options			317,917		(317,917)		0
Other comprehensive income (loss)				(7,847,061)			(7,847,061)
Ending balance at Dec. 31, 2021	$ 287,562	$ 56,492	$ 304,889,481	$ 3,283,551	$ 263,745,358	$ (41,226,357)	$ 531,036,087
Ending balance (in shares) at Dec. 31, 2021	28,756,203	5,649,240