Membership Interests (Schedule Of Changes To Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (131,000,000)
Balance at end of period	(129,000,000)
Tax expense cash flow hedges reclassified from AOCI	0	$ 0
Cash Flow Hedges - Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(36,000,000)	(39,000,000)
Defined benefit pension plans
Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax $-)	1,000,000	1,000,000
Balance at end of period	(35,000,000)	(38,000,000)
Defined Benefit Pension and OPEB Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(95,000,000)	(112,000,000)
Defined benefit pension plans	1,000,000	1,000,000
Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax $-)
Balance at end of period	(94,000,000)	(111,000,000)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(131,000,000)	(151,000,000)
Defined benefit pension plans	1,000,000	1,000,000
Cash flow hedge amounts reclassified from AOCI and reported in interest expense and related charges (net of tax $-)	1,000,000	1,000,000
Balance at end of period	$ (129,000,000)	$ (149,000,000)