Organization, Basis of Presentation and Significant Accounting Policies (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2009
Summary of changes in goodwill
Goodwill, Beginning Balance	$ 5,575,000,000	$ 5,575,000,000
Merger with Allegheny	866,000,000
Goodwill, Ending Balance	6,441,000,000	5,575,000,000
Regulated Distribution [Member]
Summary of changes in goodwill
Goodwill, Beginning Balance	5,551,000,000	5,551,000,000
Merger with Allegheny	0
Goodwill, Ending Balance	5,551,000,000	5,551,000,000
Competitive Energy Services
Summary of changes in goodwill
Goodwill, Beginning Balance	24,000,000	24,000,000
Merger with Allegheny	866,000,000
Goodwill, Ending Balance	890,000,000	24,000,000
Regulated Independent Transmission [Member]
Summary of changes in goodwill
Goodwill, Beginning Balance	0	0
Merger with Allegheny	0
Goodwill, Ending Balance	0	0
Unallocated Amount to Segment [Member]
Summary of changes in goodwill
Goodwill, Beginning Balance	0
Merger with Allegheny	0
Goodwill, Ending Balance	$ 0