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	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Interest Rate Swaps [Member] | Cash Flow Hedge [Member] | Interest Expense [Member]
Unrealized (Loss) Recognized in Other Comprehensive Income ("OCI") on Derivative (Effective Portion)	$ 0	[1]	$ (0.5)	[1]
Amount of Loss Reclassified from Accumulated OCI into Income (Effective Portion)	0	[1]	5.8	[1]
Amount of Loss Recognized in Statements of Income (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	[1]	0	[1]
Interest Rate Swaps [Member] | Not-Designated [Member] | Other Income Loss [Member]
Amount of (Loss) Recognized in Statements of Income	(0.7)
Interest Rate Cap [Member] | Not-Designated [Member] | Other Income Loss [Member]
Amount of (Loss) Recognized in Statements of Income	$ 0		$ 0

[1] The results include the interest rate swap gain (loss) prior to discontinuation in May 2011.