Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Segment Financial Information
External revenues	$ 4,076		$ 3,544
Internal revenues	2		32
Total revenues	4,078	[1]	3,576	[1]
Depreciation and amortization	360		357
Investment income	11		21
Net interest charges	229		213
Income taxes	222		111
Net income	306		47
Total assets	47,691		48,565		47,326
Total goodwill	6,444		6,507		6,441
Property additions	589		449
Regulated Distribution
Segment Financial Information
External revenues	2,383		2,268
Internal revenues	0		0
Total revenues	2,383		2,268
Depreciation and amortization	234		250
Investment income	24		25
Net interest charges	142		131
Income taxes	108		64
Net income	183		109
Total assets	27,551		27,766
Total goodwill	5,551		5,551
Property additions	301		177
Competitive Energy Services
Segment Financial Information
External revenues	1,607		1,254
Internal revenues	268		343
Total revenues	1,875		1,597
Depreciation and amortization	100		88
Investment income	6		6
Net interest charges	54		68
Income taxes	83		9
Net income	141		15
Total assets	17,187		17,399
Total goodwill	893		956
Property additions	243		214
Regulated Independent Transmission
Segment Financial Information
External revenues	109		67
Internal revenues	0		0
Total revenues	109		67
Depreciation and amortization	18		13
Investment income	0		0
Net interest charges	12		9
Income taxes	20		7
Net income	34		12
Total assets	2,452		2,486
Total goodwill	0		0
Property additions	28		27
Other/Corporate
Segment Financial Information
External revenues	(24)		(23)
Internal revenues	0		0
Total revenues	(24)		(23)
Depreciation and amortization	8		6
Investment income	0		0
Net interest charges	21		19
Income taxes	(16)		0
Net income	(28)		(55)
Total assets	501		914
Total goodwill	0		0
Property additions	17		31
Reconciling Adjustments
Segment Financial Information
External revenues	1		(22)
Internal revenues	(266)		(311)
Total revenues	(265)		(333)
Depreciation and amortization	0		0
Investment income	(19)		(10)
Net interest charges	0		(14)
Income taxes	27		31
Net income	(24)		(34)
Total assets	0		0
Total goodwill	0		0
Property additions	$ 0		$ 0

[1] Includes excise tax collections of $121 million and $119 million in the three months ended March 31, 2012 and 2011, respectively.