Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts
Balance at Beginning of the Period	$ 58.1	$ 57.9	$ 48.8
Expense	85.8	86.2	54.6
Deferral	(35.9)	(32.5)	12.9
Net Write-offs	(46.3)	(53.5)	(58.4)
Balance at End of the Period	$ 61.7	$ 58.1	$ 57.9