Consolidated Statement of Stockholders' Equity (Unaudited) (USD $)	Total	Common Class A [Member]	Common Class B [Member]	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings	Treasury Stock
Beginning balance at Dec. 31, 2010	$ 380,102,810	$ 206,566	$ 56,492	$ 167,093,504	$ 8,561,086	$ 213,435,095	$ (9,249,933)
Beginning balance, shares at Dec. 31, 2010		20,656,527	5,649,240
Issuance of common stock (stock compensation plans)	898,507	601		897,906
Issuance of common stock (stock compensation plans), shares		60,147
Net income	1,331,873					1,331,873
Cash dividends declared	(6,006,855)					(6,006,855)
Grant of stock options				2,283,860		(2,283,860)
Repurchase of treasury stock	(1,480,395)						(1,480,395)
Other comprehensive income	12,811,862				12,811,862
Ending balance at Sep. 30, 2011	$ 387,657,802	$ 207,167	$ 56,492	$ 170,275,270	$ 21,372,948	$ 206,476,253	$ (10,730,328)
Ending balance, shares at Sep. 30, 2011		20,716,674	5,649,240