Investment In Oncor Holdings (Oncor Holdings Financial Statements) (Details) (Variable Interest Entity, Primary Beneficiary [Member], Oncor Holdings [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Variable Interest Entity, Primary Beneficiary [Member] | Oncor Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Operating revenues	$ 1,054	$ 966	$ 2,883	$ 2,640
Operation and maintenance expenses	(376)	(315)	(1,074)	(919)
Depreciation and amortization	(218)	(207)	(638)	(608)
Taxes other than income taxes	(115)	(112)	(330)	(315)
Other income	3	4	10	14
Other deductions	(4)	(2)	(11)	(11)
Interest income	1	0	3	2
Interest expense and related charges	(89)	(94)	(266)	(283)
Income before income taxes	256	240	577	520
Income tax expense	(101)	(97)	(230)	(199)
Net income	155	143	347	321
Net income attributable to noncontrolling interests	(32)	(29)	(71)	(66)
Net income attributable to Oncor Holdings	123	114	276	255
Current assets:
Cash and cash equivalents	17		17		28
Restricted cash	67		67		52
Trade accounts receivable — net	469		469		385
Trade accounts and other receivables from affiliates	152		152		135
Income taxes receivable from EFH Corp.	0		0		16
Inventories	76		76		65
Accumulated deferred income taxes	11		11		32
Prepayments and other current assets	89		89		82
Total current assets	881		881		795
Restricted cash	16		16		16
Other investments	96		96		91
Property, plant and equipment — net	12,270		12,270		11,902
Goodwill	4,064		4,064		4,064
Regulatory assets — net	1,111		1,111		1,324
Other noncurrent assets	69		69		71
Total assets	18,507		18,507		18,263
Current liabilities:
Short-term borrowings	720		720		745
Long-term debt due currently	636		636		131
Trade accounts payable — nonaffiliates	133		133		178
Income taxes payable to EFH Corp.	56		56		23
Accrued taxes other than income	145		145		169
Accrued interest	65		65		95
Other current liabilities	150		150		135
Total current liabilities	1,905		1,905		1,476
Accumulated deferred income taxes	1,839		1,839		1,905
Long-term debt, less amounts due currently	5,041		5,041		5,381
Other noncurrent liabilities and deferred credits	1,837		1,837		1,822
Total liabilities	$ 10,622		$ 10,622		$ 10,584