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					456,716		456,716
Other comprehensive income				(289,996)			(289,996)
Grant of stock options			193,032				193,032
Sale of treasury stock			(45,303)			255,218	209,915
Stock dividends	218	2	(29)		(191)
Conversion Class C to Class A	1,370	(1,371)	1
Balance at Sep. 30, 2011	18,359,478	1,930,662	19,837,694	898,250	22,364,104	(2,892,053)	60,498,135
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					9,245,262		9,245,262
Other comprehensive income				(161,557)			(161,557)
Grant of stock options			187,510				187,510
Sale of treasury stock			(97,983)			344,961	246,978
Conversion Class C to Class A	646	(645)	(1)
Balance at Sep. 30, 2012	$ 19,278,242	$ 2,026,550	$ 19,577,091	$ 492,886	$ 31,791,885	$ (2,417,874)	$ 70,748,780