Fair Value Measurements (Schedule Of Face And Fair Value Of Debt) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Face Value	$ 2,067,300,000	$ 2,005,300,000
Fair Value	2,372,000,000	2,281,200,000
Fixed Rate [Member]
Debt Instrument [Line Items]
Face Value	1,955,300,000	1,955,300,000
Fair Value	2,260,000,000	2,231,200,000
Variable Rate [Member]
Debt Instrument [Line Items]
Face Value	112,000,000	50,000,000
Fair Value	$ 112,000,000	$ 50,000,000