Membership Interests (Membership Interests) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended										9 Months Ended			9 Months Ended
	Jan. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013		Sep. 30, 2013 Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2014 Capital Accounts [Member]	Sep. 30, 2013 Capital Accounts [Member]		Sep. 30, 2013 Long-Term Debt of Affiliate Held by EFIH [Member]	Sep. 30, 2014 Long-Term Debt of Affiliate Held by EFIH [Member]	Dec. 31, 2013 Long-Term Debt of Affiliate Held by EFIH [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income [Member]	Sep. 30, 2014 Accumulated Other Comprehensive Income [Member]	Dec. 31, 2013 Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Dedesignated Cash Flow Hedges - Oncor [Member] Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Changes in Fair Values of Investment in Debt Securities of Affiliates [Member] Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Pension and Other Postretirement Employee Benefit Liabilities Adjustments - Oncor [Member] Reclassification out of Accumulated Other Comprehensive Income [Member]	Sep. 30, 2013 Additional Paid-in Capital [Member]	Sep. 30, 2014 Senior Notes [Member]	Sep. 30, 2014 Energy Future Holdings Corp. [Member] Senior Notes [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ (179)			$ (1,822)	$ (179)			$ (1,148)	$ 5,049		$ (5,388)	$ (635)	$ (635)	$ 160	$ (39)	$ (39)
Net income		69	(14)	(357)	68			(357)	68		0
Cash distributions to EFH Corp.	(680)				(680)				(680)		0
Push-down of deferred net loss on debt exchanges, net of tax					13				13
Effect of debt push-down from EFH Corp.				16	437	[1]		16	437	[1]	0
Distribution to EFH Corp. of debt held as investment				0	(5,778)				(5,778)
Debt Instrument, Principal Amount of Debt Returned to Affiliate																					5,125
EFH Corp. debt distributed to EFH Corp. ($5.125 billion principal amount)					4,524						4,524
Net effects related to Oncor					1						0			1
Net affiliate debt received in debt exchanges ($31 million principal amount)					(23)						(23)
Principal Amount Of Affiliate Debt Acquired In Exchange Transaction																						31
Interest received on holdings of affiliate debt (Note 10)				0	208						208
Deferred Tax On Interest Received On Holdings Of Long Term Debt Of Affiliates				0	(73)				(73)
Recognition in interest income of mark-to-market valuations of investments in affiliate debt upon distribution to EFH Corp.		0	0	0	(185)									(185)
Stockholders' Equity, Other					(1)						(1)			0						0
Ending Balance		(2,163)	(1,668)	(2,163)	(1,668)			(1,489)	(964)		(680)	(635)	(635)	(24)	(39)	(39)
Effect of Reduction of Push Down Debt					420
Amounts reclassified from accumulated other comprehensive income (loss) and reported in:
Balance at December 31, 2012				(39)			160										(23)	185	(2)
Interest income							(284)										0	(284)	0
Equity in earnings (losses) of unconsolidated subsidiaries		123	114	276	255		1										2	0	(1)
Income tax benefit		25	68	215	100		99										0	99	0
Total amount reclassified from accumulated other comprehensive income (loss) during the period		(1)	1	0	(184)		(184)										2	(185)	(1)
Balance at September 30, 2013		$ (39)		$ (39)			$ (24)										$ (21)	$ 0	$ (3)

[1] (a)Represents the effect of a reduction of $420 million of debt pushed down from EFH Corp and related interest and income tax effects.