Other Material Contingencies (Total Guarantees) (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 862	$ 859
Guarantee Duration, 0-3 Years [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	692
Guarantee Duration, 0-3 Years [Member] | Financial And Performance Guarantee For Commodity Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	652
Guarantee Duration, 0-3 Years [Member] | Financial And Performance Guarantee For Intra-Company [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	15
Guarantee Duration, 0-3 Years [Member] | Financial And Performance Guarantee Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	25
Guarantee Duration, 4-10 Years [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	16
Guarantee Duration, 4-10 Years [Member] | Financial And Performance Guarantee For Commodity Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	3
Guarantee Duration, 4-10 Years [Member] | Financial And Performance Guarantee For Intra-Company [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term
Guarantee Duration, 4-10 Years [Member] | Financial And Performance Guarantee Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	13
Guarantee Duration, Greater Than 10 Years [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	154
Guarantee Duration, Greater Than 10 Years [Member] | Financial And Performance Guarantee For Commodity Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	153
Guarantee Duration, Greater Than 10 Years [Member] | Financial And Performance Guarantee For Intra-Company [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	1
Guarantee Duration, Greater Than 10 Years [Member] | Financial And Performance Guarantee Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term
Financial And Performance Guarantee For Commodity Transactions [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	808
Financial And Performance Guarantee For Intra-Company [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	16
Financial And Performance Guarantee Other [Member]
Guarantor Obligations [Line Items]
Total guarantees, by type and term	$ 38