Other Material Contingencies (Total Guarantees) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Guarantee obligations maximum exposure	$ 834	$ 859
Guarantee Duration, 0-3 Years [Member]
Guarantee obligations maximum exposure	671
Guarantee Duration, 0-3 Years [Member] | Financial and Performance Guarantee for Commodity Transactions [Member]
Guarantee obligations maximum exposure	616
Guarantee Duration, 0-3 Years [Member] | Financial and Performance Guarantee for Intra-Company [Member]
Guarantee obligations maximum exposure	15
Guarantee Duration, 0-3 Years [Member] | Financial and Performance Guarantee Other [Member]
Guarantee obligations maximum exposure	40
Guarantee Duration, 4-10 Years [Member]
Guarantee obligations maximum exposure	22
Guarantee Duration, 4-10 Years [Member] | Financial and Performance Guarantee for Commodity Transactions [Member]
Guarantee obligations maximum exposure	8
Guarantee Duration, 4-10 Years [Member] | Financial and Performance Guarantee Other [Member]
Guarantee obligations maximum exposure	14
Guarantee Duration, Greater than 10 Years [Member]
Guarantee obligations maximum exposure	141
Guarantee Duration, Greater than 10 Years [Member] | Financial and Performance Guarantee for Commodity Transactions [Member]
Guarantee obligations maximum exposure	140
Guarantee Duration, Greater than 10 Years [Member] | Financial and Performance Guarantee for Intra-Company [Member]
Guarantee obligations maximum exposure	1
Financial and Performance Guarantee for Commodity Transactions [Member]
Guarantee obligations maximum exposure	764
Financial and Performance Guarantee for Intra-Company [Member]
Guarantee obligations maximum exposure	16
Financial and Performance Guarantee Other [Member]
Guarantee obligations maximum exposure	$ 54