Investments In Unconsolidated Affiliates And Related Party Transactions (Investments In Equity Method Unconsolidated Affiliates) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Investments in unconsolidated affiliates	$ 460	$ 444
U.S. Franchised Electric And Gas [Member]
Investments in unconsolidated affiliates	5	5
Commercial Power [Member]
Investments in unconsolidated affiliates	188	175
International Energy [Member]
Investments in unconsolidated affiliates	91	83
Other Investment Companies [Member]
Investments in unconsolidated affiliates	176	181
Domestic Equity Method Investments [Member]
Investments in unconsolidated affiliates	360	352
Domestic Equity Method Investments [Member] | U.S. Franchised Electric And Gas [Member]
Investments in unconsolidated affiliates	5	5
Domestic Equity Method Investments [Member] | Commercial Power [Member]
Investments in unconsolidated affiliates	188	174
Domestic Equity Method Investments [Member] | Other Investment Companies [Member]
Investments in unconsolidated affiliates	167	173
International Equity Method Investments [Member]
Investments in unconsolidated affiliates	100	92
International Equity Method Investments [Member] | Commercial Power [Member]
Investments in unconsolidated affiliates		1
International Equity Method Investments [Member] | International Energy [Member]
Investments in unconsolidated affiliates	91	83
International Equity Method Investments [Member] | Other Investment Companies [Member]
Investments in unconsolidated affiliates	$ 9	$ 8