Supplementary Financial Information (Schedule Of Intangible Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,718	$ 1,707
Accumulated Amortization	587	568
Net	1,131	1,139
Land Easements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	643	641
Accumulated Amortization	119	117
Net	524	524
Capitalized Software [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,075	1,066
Accumulated Amortization	468	451
Net	$ 607	$ 615