Retirement Benefits (Schedule Of Allocation Of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
DB Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 3,599	$ 3,402	$ 2,546
DB Pension Plans | Plan Assets Excluding Pooled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,698	1,828
DB Pension Plans | Plan Assets Excluding Pooled Funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	815	1,086
DB Pension Plans | Plan Assets Excluding Pooled Funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	883	742
DB Pension Plans | Cash and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets	30	115
DB Pension Plans | Cash and short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	30	115
DB Pension Plans | U.S. government and agencies securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	209	150
DB Pension Plans | U.S. government and agencies securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	209	150
DB Pension Plans | Corporate debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	595	540
DB Pension Plans | Corporate debt | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	595	540
DB Pension Plans | State and municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13	11
DB Pension Plans | State and municipal bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13	11
DB Pension Plans | Foreign corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	66	41
DB Pension Plans | Foreign corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	66	41
DB Pension Plans | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	785	971
DB Pension Plans | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	785	971
DB Pension Plans | Pooled funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,901	1,574
OPEB Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,787	1,645	$ 1,509
OPEB Plan | Plan Assets Excluding Pooled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,155	995
OPEB Plan | Plan Assets Excluding Pooled Funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,047	906
OPEB Plan | Plan Assets Excluding Pooled Funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	108	89
OPEB Plan | Cash and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets	21	33
OPEB Plan | Cash and short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	21	33
OPEB Plan | U.S. government and agencies securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	25	18
OPEB Plan | U.S. government and agencies securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	25	18
OPEB Plan | Corporate debt
Defined Benefit Plan Disclosure [Line Items]
Plan assets	73	64
OPEB Plan | Corporate debt | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	73	64
OPEB Plan | State and municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2	2
OPEB Plan | State and municipal bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	2	2
OPEB Plan | Foreign corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	8	5
OPEB Plan | Foreign corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	8	5
OPEB Plan | Common stocks
Defined Benefit Plan Disclosure [Line Items]
Plan assets	85	66
OPEB Plan | Common stocks | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	85	66
OPEB Plan | Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	941	807
OPEB Plan | Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	941	807
OPEB Plan | Pooled funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 632	$ 650