Debt (Balances Outstanding) (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Revolving Credit Facility [Member] 4 Year Revolving Credit Facility [Member]	Dec. 31, 2013 Revolving Credit Facility [Member] 5 Year Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Long-term Debt, Excluding Current Maturities	$ 6,106	$ 6,806
Commercial Paper and Revolving Credit Facility
Maximum amount available under the line of credit facility	$ 2,000
Term of Credit Facility			4 years	5 years