Basis of Presentation (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010		Jun. 30, 2010 As Reported [Member]	Jun. 30, 2010 Correction [Member]	Dec. 31, 2008 Correction [Member]	Dec. 31, 2007 Correction [Member]
Assets
Current deferred income taxes	$ 44,794,000	$ 53,794,000	$ 57,575,000	[1]	$ 59,525,000	$ (1,950,000)
Prepaid expenses	21,659,000	19,374,000	33,972,000	[1]	42,422,000	(8,450,000)
Total current assets	892,353,000	772,106,000	856,903,000	[1]	867,303,000	(10,400,000)
Goodwill	3,097,016,000	3,097,016,000	3,096,300,000	[1]	3,093,979,000	2,321,000	2,321,000
Total assets	8,385,610,000	8,337,891,000	8,486,965,000	[1]	8,495,044,000	(8,079,000)
Liabilities
Noncurrent deferred income taxes	762,406,000	849,448,000	843,408,000	[1]	836,702,000	6,706,000		(14,785,000)
Total liabilities	4,504,345,000	4,372,911,000	4,457,646,000	[1]	4,450,940,000	6,706,000
Equity
Retained earnings	1,385,208,000	1,512,863,000	1,610,835,000	[1]	1,625,620,000	(14,785,000)		14,785,000
Total shareholders' equity			4,029,319,000		4,044,104,000	(14,785,000)
Total liabilities and equity	$ 8,385,610,000	$ 8,337,891,000	$ 8,486,965,000	[1]	$ 8,495,044,000	$ (8,079,000)

[1] As Restated, See Note 1