Statements of Stockholders' Equity (USD $)	Class A Common Stock	Class C Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock	Total
Balance at Dec. 31, 2010	$ 18,357,890	$ 1,932,031	$ 19,689,993	$ 1,188,246	$ 21,907,579	$ (3,147,271)	$ 59,928,468
Net earnings					1,298,758		1,298,758
Other comprehensive loss				(533,803)			(533,803)
Grant of stock options			253,934				253,934
Sale of treasury stock			(101,206)			384,436	283,230
Stock dividends	918,336	96,535	(355,157)		(659,714)
Conversion Class C to Class A	1,370	(1,371)	1
Balance at Dec. 31, 2011	19,277,596	2,027,195	19,487,565	654,443	22,546,623	(2,762,835)	61,230,587
Net earnings					16,712,518		16,712,518
Other comprehensive loss				1,279,916			1,279,916
Grant of stock options			251,031				251,031
Exercise stock options	1,371,506	63,782	(1,416,982)				18,306
Sale of treasury stock			(62,650)			382,401	319,751
Stock dividends	1,037,404	104,488	3,003,177		(4,145,069)
Conversion Class C to Class A	646	(645)	(1)
Balance at Dec. 31, 2012	21,687,152	2,194,820	21,262,140	1,934,359	35,114,072	(2,380,434)	79,812,109
Net earnings					7,585,921		7,585,921
Other comprehensive loss				(715,963)			(715,963)
Grant of stock options			88,369				88,369
Exercise stock options	719,572	422,422	(345,845)			(543,334)	252,815
Sale of treasury stock			428,794			299,143	727,937
Stock dividends	1,124,304	126,685	1,782,418		(3,033,406)		1
Conversion Class C to Class A	83,546	(83,545)	(1)
Balance at Dec. 31, 2013	$ 23,614,574	$ 2,660,382	$ 23,215,875	$ 1,218,396	$ 39,666,587	$ (2,624,625)	$ 87,751,189