Segment Information (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010		Dec. 31, 2010
Segment Financial Information
External revenues	$ 4,048,000,000		$ 3,139,000,000		$ 7,592,000,000		$ 6,371,000,000
Internal revenues	12,000,000				44,000,000		67,000,000
Total revenues	4,060,000,000	[1]	3,139,000,000	[1]	7,636,000,000	[1]	6,438,000,000	[1]
Depreciation and amortization	372,000,000		351,000,000		724,000,000		756,000,000
Investment income (loss), net	31,000,000		31,000,000		52,000,000		47,000,000
Net interest charges	245,000,000		167,000,000		458,000,000		339,000,000
Income taxes	101,000,000		134,000,000		179,000,000		245,000,000
Net income (loss)	171,000,000		256,000,000		216,000,000		405,000,000
Total assets	47,596,000,000		34,466,000,000		47,596,000,000		34,466,000,000		34,805,000,000
Total goodwill	6,456,000,000		5,575,000,000		6,456,000,000		5,575,000,000		5,575,000,000
Property additions	569,000,000		489,000,000		1,018,000,000		997,000,000
Regulated Distribution
Segment Financial Information
External revenues	2,485,000,000		2,314,000,000		4,753,000,000		4,798,000,000
Internal revenues			19,000,000				19,000,000
Total revenues	2,485,000,000		2,333,000,000		4,753,000,000		4,817,000,000
Depreciation and amortization	240,000,000		264,000,000		485,000,000		577,000,000
Investment income (loss), net	27,000,000		28,000,000		52,000,000		54,000,000
Net interest charges	145,000,000		124,000,000		276,000,000		248,000,000
Income taxes	108,000,000		81,000,000		164,000,000		143,000,000
Net income (loss)	184,000,000		132,000,000		280,000,000		235,000,000
Total assets	26,932,000,000		21,457,000,000		26,932,000,000		21,457,000,000
Total goodwill	5,551,000,000		5,551,000,000		5,551,000,000		5,551,000,000		5,551,000,000
Property additions	302,000,000		157,000,000		479,000,000		309,000,000
Competitive Energy Services
Segment Financial Information
External revenues	1,495,000,000		795,000,000		2,736,000,000		1,514,000,000
Internal revenues	318,000,000		539,000,000		661,000,000		1,213,000,000
Total revenues	1,813,000,000		1,334,000,000		3,397,000,000		2,727,000,000
Depreciation and amortization	107,000,000		71,000,000		195,000,000		148,000,000
Investment income (loss), net	15,000,000		13,000,000		21,000,000		14,000,000
Net interest charges	67,000,000		33,000,000		122,000,000		66,000,000
Income taxes	7,000,000		75,000,000		10,000,000		117,000,000
Net income (loss)	12,000,000		121,000,000		17,000,000		190,000,000
Total assets	17,146,000,000		11,102,000,000		17,146,000,000		11,102,000,000
Total goodwill	905,000,000		24,000,000		905,000,000		24,000,000		24,000,000
Property additions	197,000,000		290,000,000		411,000,000		619,000,000
Regulated Independent Transmission
Segment Financial Information
External revenues	105,000,000		59,000,000		172,000,000		116,000,000
Total revenues	105,000,000		59,000,000		172,000,000		116,000,000
Depreciation and amortization	18,000,000		13,000,000		31,000,000		25,000,000
Net interest charges	11,000,000		5,000,000		20,000,000		10,000,000
Income taxes	18,000,000		7,000,000		25,000,000		14,000,000
Net income (loss)	31,000,000		11,000,000		44,000,000		23,000,000
Total assets	2,339,000,000		993,000,000		2,339,000,000		993,000,000
Total goodwill	0				0				0
Property additions	45,000,000		15,000,000		72,000,000		29,000,000
Other/Corporate
Segment Financial Information
External revenues	(30,000,000)		(21,000,000)		(53,000,000)		(43,000,000)
Total revenues	(30,000,000)		(21,000,000)		(53,000,000)		(43,000,000)
Depreciation and amortization	7,000,000		3,000,000		13,000,000		6,000,000
Investment income (loss), net	1,000,000				1,000,000		1,000,000
Net interest charges	21,000,000		9,000,000		40,000,000		22,000,000
Income taxes	(30,000,000)		(12,000,000)		(50,000,000)		(24,000,000)
Net income (loss)	(51,000,000)		(20,000,000)		(86,000,000)		(39,000,000)
Total assets	1,179,000,000		914,000,000		1,179,000,000		914,000,000
Total goodwill	0				0				0
Property additions	25,000,000		27,000,000		56,000,000		40,000,000
Reconciling Adjustments
Segment Financial Information
External revenues	(7,000,000)		(8,000,000)		(16,000,000)		(14,000,000)
Internal revenues	(306,000,000)		(558,000,000)		(617,000,000)		(1,165,000,000)
Total revenues	(313,000,000)		(566,000,000)		(633,000,000)		(1,179,000,000)
Investment income (loss), net	(12,000,000)		(10,000,000)		(22,000,000)		(22,000,000)
Net interest charges	1,000,000		(4,000,000)				(7,000,000)
Income taxes	(2,000,000)		(17,000,000)		30,000,000		(5,000,000)
Net income (loss)	$ (5,000,000)		$ 12,000,000		$ (39,000,000)		$ (4,000,000)

[1] *Includes excise tax collections of $116 million and $99 million in the three months ended June 30,2011 and 2010, respectively, and $235 million and $208 million in the six months ended June 30, 2011 and 2010, respectively.