Financial Instruments And Derivatives (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Financial Instruments And Derivatives [Line Items]
Estimated fair value of total long-term debt, including capitalized lease obligations	$ 9,800,000,000	$ 12,800,000,000
Recorded book values of total long-term debt, including capitalized lease obligations	9,322,000,000	12,227,000,000
Derivative asset at fair value, net		172,000,000
Derivative liability at fair value, net	3,000,000
Gain (loss) before-tax earnings impact of derivatives	131,000,000	221,000,000	(73,000,000)
Cash Flow Hedges [Member]
Financial Instruments And Derivatives [Line Items]
Gain (loss) before-tax earnings impact of derivatives	$ 136,000,000