Organization, Basis of Presentation and Significant Accounting Policies (Details 5) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of changes in goodwill
Goodwill, Ending Balance	$ 6,418	$ 6,418	$ 6,447
Regulated Distribution
Summary of changes in goodwill
Goodwill, Ending Balance	5,092	5,092	5,025
Competitive Energy Services
Summary of changes in goodwill
Goodwill, Ending Balance	800	800	896
Scenario, Previously Reported [Member]
Summary of changes in goodwill
Goodwill, Ending Balance	6,418
Scenario, Previously Reported [Member] | Regulated Distribution
Summary of changes in goodwill
Goodwill, Ending Balance	5,092
Scenario, Previously Reported [Member] | Regulated Transmission
Summary of changes in goodwill
Goodwill, Ending Balance	526
Scenario, Previously Reported [Member] | Competitive Energy Services
Summary of changes in goodwill
Goodwill, Ending Balance	$ 800