Investments (Details Textuals 17) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Investments [Abstract]
Increase (decrease) in estimated fair value of derivatives related to economic hedges in equity method international joint investments that do not qualify for hedge accounting	$ 0	$ (12)	$ 23	$ 65

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