Related-Party Transactions (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Sep. 30, 2014
Related Party Transaction [Line Items]
Revenue from related party		$ 224	$ 225	$ 460	$ 465
Electricity delivery fee revenues				460
TCEH [Member]
Related Party Transaction [Line Items]
Revenue from related party				1	1
Electricity delivery fee revenues		224	225		465
Delivery fee surcharges		4	4	8	8
Letter of credit		9		9		$ 9
EFH Corp [Member]
Related Party Transaction [Line Items]
Cash income tax refund 2007 audit							$ 45
Cash income tax refund 2003 to 2006 audit						$ 11
Cash income tax refund 2008 to 2009 audit		8		8
Noncurrent liability related to taxes		4		4
Amounts receivable from members under tax agreement		4		4
Administrative and services costs		4	7	9	15
Shared facilities expense		1	1	2	2
Reimbursement payment amount	$ 1
Maximum [Member] | EFH Corp [Member]
Related Party Transaction [Line Items]
Shared facilities payments received		$ 1	$ 1	$ 1	$ 1