CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands	Total	Treasury Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Comprehensive Income	Accumulated Other Comprehensive (Loss) Income Foreign Currency Translation	Accumulated Other Comprehensive (Loss) Income Marketable Securities
Beginning Balance at Dec. 31, 2008		$ (47,405)	$ 45,378	$ 179,191	$ 585,827		$ (1,359)	$ (88)
Beginning Balance (in shares) at Dec. 31, 2008		(10,280)
Dividends, $.046, $.049 and $.054 per share in 2009, 2010 and 2011, respectively					(3,739)
Stock-Based Compensation				3,565
Exchange of Common Stock for Class A Common Stock (in shares)		(144)
Exchange of Common Stock for Class A Common Stock		(9,073)		9,073
Reissued Shares (in shares)		1,026
Reissued Shares		7,103		4,840
Net Earnings from Continuing Operations	112,878				112,878	112,878
Loss From Discontinued Operations	(277)				(277)	(277)
Foreign Currency Translation Adjustment, net of Income Taxes of $356 and $187 in 2010 and 2011, respectively						1,346	1,346
Comprehensive Income	113,900					113,947
Ending Balance at Dec. 31, 2009		(49,375)	45,378	196,669	694,689		(13)	(88)
Ending Balance (in shares) at Dec. 31, 2009		(9,398)
Dividends, $.046, $.049 and $.054 per share in 2009, 2010 and 2011, respectively					(3,981)
Stock-Based Compensation				4,759
Reissued Shares (in shares)		212
Reissued Shares		743		324
Repurchased Shares (in shares)		(1,479)
Repurchased Shares		(29,009)
Stock Recombination			(2)
Net Earnings from Continuing Operations	118,376				118,376	118,376
Foreign Currency Translation Adjustment, net of Income Taxes of $356 and $187 in 2010 and 2011, respectively						947	591
Comprehensive Income	119,300					119,323
Ending Balance at Dec. 31, 2010	979,417	(77,641)	45,376	201,752	809,084		578	(88)
Ending Balance (in shares) at Dec. 31, 2010		(10,665)
Dividends, $.046, $.049 and $.054 per share in 2009, 2010 and 2011, respectively					(4,152)
Stock-Based Compensation				8,385
Reissued Shares (in shares)		737
Reissued Shares		7,493		2,174
Repurchased Shares (in shares)		(5,184)
Repurchased Shares		(129,958)
Net Earnings from Continuing Operations	113,767				113,767	113,767
Reclassification Into Earnings of Available for Sale Securities, Net of Tax of $54								88
Foreign Currency Translation Adjustment, net of Income Taxes of $356 and $187 in 2010 and 2011, respectively						(304)	(304)
Comprehensive Income	113,200					113,463
Ending Balance at Dec. 31, 2011	$ 976,554	$ (200,106)	$ 45,376	$ 212,311	$ 918,699		$ 274
Ending Balance (in shares) at Dec. 31, 2011		(15,112)