Valuation And Qualifying Accounts (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Valuation and Qualifying Accounts Disclosure [Line Items]
Provision for doubtful accounts	$ 13,708,000		$ 19,214,000		$ 20,178,000
Allowance For Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of Year	21,000,000		26,400,000		27,100,000
Provision for doubtful accounts	13,700,000	[1]	19,200,000	[1]	20,200,000	[1]
Write-offs	(17,300,000)		(24,600,000)		(21,100,000)
Acquired through acquisitions					200,000
Balance at end of Year	17,400,000		21,000,000		26,400,000
Allowance For Doubtful Accounts, Discontinued Operations [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Provision for doubtful accounts	200,000		500,000		500,000
Provision for estimated revenue adjustments	300,000		500,000		200,000
Estimated Revenue Adjustments [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of Year	6,500,000		8,700,000		7,200,000
Provision for estimated revenue adjustments	12,100,000	[2]	7,000,000	[2]	8,800,000	[2]
Write-offs	(11,800,000)		(9,200,000)		(7,300,000)
Balance at end of Year	$ 6,800,000		$ 6,500,000		$ 8,700,000

[1] Includes $0.2 million, $0.5 million and $0.5 million from discontinued operations for the years ended December 31, 2011, 2010 and 2009, respectively.

[2] Includes $0.3 million, $0.5 million and $0.2 million from discontinued operations for the years ended December 31, 2011, 2010 and 2009, respectively.