Debt (Fair Value Of Fixed Rate Notes) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Apr. 30, 2015
$612.5 million fixed rate notes due March 2018, interest equal to 4.40% [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 612.5	$ 612.5
Debt Instrument, Maturity Date	Mar. 01, 2018
$750 Million Fixed Rate Notes Due March 2022, Interest Equal To 3.0% [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 750.0
Debt Instrument, Maturity Date	Sep. 01, 2022
$750.0 Million Fixed Rate Notes Due March 2043, Interest Equal To 5.3% [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 750.0
Debt Instrument, Maturity Date	Sep. 01, 2043