Fair Value Of Financial Instruments (Carrying And Fair Values Of Our Other Financial Assets And Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Marketable securities:
Long-term debt, including current portion	$ (3,930)		$ (3,203)
Carrying Value [Member]
Marketable securities:
Available-for-sale	70	[1]	47	[1]
Held-to-maturity	178	[1]	165	[1]
Other investments	145	[1]	113	[1]
Derivatives	34	[1]	130	[1]
Long-term debt, including current portion	(3,930)	[1]	(3,203)	[1]
Fair Value [Member]
Marketable securities:
Available-for-sale	70	[1]	47	[1]
Held-to-maturity	175	[1]	165	[1]
Other investments	145	[1]	113	[1]
Derivatives	34	[1]	130	[1]
Long-term debt, including current portion	(4,199)	[1]	(3,436)	[1]
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Marketable securities:
Available-for-sale	70	[1]	47	[1]
Other investments	89	[1]	55	[1]
Significant Other Observable Inputs (Level 2) [Member]
Marketable securities:
Held-to-maturity	175	[1],[2]	165	[1],[2]
Other investments	56	[1],[2]	58	[1],[2]
Derivatives	34	[1],[2]	130	[1],[2]
Long-term debt, including current portion	$ (4,199)	[1],[2]	$ (3,436)	[1],[2]

[1] We had no Level 3 financial instruments on December 31, 2010 or 2011.

[2] Determined under a market approach using valuation models that incorporate observable inputs such as interest rates, bond yields and quoted prices for similar assets and liabilities.