Derivative Instruments And Hedging Activities (Effect Of Derivative Financial Instruments On The Statements Of Income And Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest Rate Cap [Member] | Not-Designated [Member] | Other Income Loss [Member]
Amount of (Loss) Recognized in Statements of Income	$ (0.1)	$ (0.1)	$ 0
Interest Rate Swap [Member] | Cash Flow Hedge [Member] | Interest Expense [Member]
Unrealized (Loss) Recognized in Other Comprehensive Income ("OCI") on Derivative (Effective Portion)	0	(2.7)	(19.1)
Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion)	0	9.9	23.4
Amount of Loss Recognized in Statements of Income (Discontinuation, Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	29.8	0
Interest Rate Swap [Member] | Not-Designated [Member] | Other Income Loss [Member]
Amount of (Loss) Recognized in Statements of Income	$ (0.7)	$ (0.2)	$ 0