Membership Interests (Schedule Of Changes To Membership Interests) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Balance			$ 7,518	$ 7,409
Net income	$ 98	$ 94	196	197
Distributions			(165)	(110)
Net effects of cash flow hedges (net of tax)	1	1	1	1
Defined benefit pension plans (net of tax)			1
Balance	7,551	7,497	7,551	7,497
Capital Accounts [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Balance			7,625	7,457
Net income			196	197
Distributions			$ (165)	$ (110)
Net effects of cash flow hedges (net of tax)
Defined benefit pension plans (net of tax)
Balance	7,656	7,544	$ 7,656	$ 7,544
Accumulated Other Comprehensive Income (Loss) [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Balance			$ (107)	$ (48)
Net income
Distributions
Net effects of cash flow hedges (net of tax)			$ 1	$ 1
Defined benefit pension plans (net of tax)			1
Balance	$ (105)	$ (47)	$ (105)	$ (47)