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Retirement Benefits (Schedule of Allocation of Plan Assets) (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
DB Pension Plans |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 2,964 | $ 3,004 | $ 2,820
DB Pension Plans | Plan Assets Excluding Pooled Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 148 | 225 |
DB Pension Plans | Plan Assets Excluding Pooled Funds | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 148 | 225 |
DB Pension Plans | Plan Assets Excluding Pooled Funds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
DB Pension Plans | Cash and short-term investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 148 | 178 |
DB Pension Plans | Cash and short-term investments | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 148 | 178 |
DB Pension Plans | Cash and short-term investments | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
DB Pension Plans | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 47 |
DB Pension Plans | Mutual funds | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 47 |
DB Pension Plans | Mutual funds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
DB Pension Plans | Pooled funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 2,816 | 2,779 |
OPEB Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 1,588 | 1,559 | $ 1,446
OPEB Plan | Plan Assets Excluding Pooled Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 356 | 402 |
OPEB Plan | Plan Assets Excluding Pooled Funds | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 258 | 303 |
OPEB Plan | Plan Assets Excluding Pooled Funds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 98 | 99 |
OPEB Plan | Cash and short-term investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 35 | 82 |
OPEB Plan | Cash and short-term investments | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 35 | 82 |
OPEB Plan | Cash and short-term investments | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | U.S. government and agencies securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 13 | 16 |
OPEB Plan | U.S. government and agencies securities | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | U.S. government and agencies securities | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 13 | 16 |
OPEB Plan | Corporate debt |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 68 | 67 |
OPEB Plan | Corporate debt | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | Corporate debt | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 68 | 67 |
OPEB Plan | State and municipal bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 2 | 1 |
OPEB Plan | State and municipal bonds | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | State and municipal bonds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 2 | 1 |
OPEB Plan | Foreign bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 15 | 15 |
OPEB Plan | Foreign bonds | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | Foreign bonds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 15 | 15 |
OPEB Plan | Common stocks |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 170 | 161 |
OPEB Plan | Common stocks | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 170 | 161 |
OPEB Plan | Common stocks | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 53 | 60 |
OPEB Plan | Mutual funds | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 53 | 60 |
OPEB Plan | Mutual funds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
OPEB Plan | Pooled funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 1,232 | $ 1,157 |

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