Debt (Narrative) (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended
	May 03, 2013
Debt Instrument [Line Items]
Debt Instrument, Issuance Date	May 03, 2013
Proceeds from Debt, Net of Issuance Costs	$ 494
0.95% Due May 15, 2018
Debt Instrument [Line Items]
Debt Instrument, Face Amount	350
Debt Instrument, Maturity Date	May 15, 2018
Debt Instrument, Interest Rate, Stated Percentage	0.95%
Floating Rate Due November 3, 2014 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 150
Debt Instrument, Maturity Date	Nov. 03, 2014
Debt Instrument, Description of Variable Rate Basis	three-month LIBOR
Debt Instrument, Basis Spread on Variable Rate	0.01%