Debt Key Components of Long-term Debt (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		3 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Long-term Notes $2.5B	Sep. 30, 2013 Long-term Notes $2.0B	Sep. 30, 2013 Long-term Notes $1.0B	Sep. 30, 2013 Long-term Notes $5.5B [Member]
Debt Instrument [Line Items]
Fair Value Inputs, Discount Rate	1.00%		99.943%	99.76%	99.925%
Long-term Debt	$ 5,493	$ 0	$ 2,499	$ 1,995	$ 999	$ 5,493