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Pension and Other Postretirement Benefit Plans - Fair Values of Other Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1,040	$ 1,045	$ 947
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	5	13
Developed markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	49	301
Emerging markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	24	80
Real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3	12
Developed markets
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	41	223
Corporate obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	598	157
Government and agency obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	266	245
Mortgage and asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	54	2
Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	12
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	44	259
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Developed markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3	24
Level 1 | Emerging markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	41	223
Level 1 | Corporate obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Government and agency obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Mortgage and asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	12
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	918	404
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Developed markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Emerging markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Corporate obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	598	157
Level 2 | Government and agency obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	266	245
Level 2 | Mortgage and asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	54	2
Level 2 | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Developed markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Emerging markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Corporate obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Government and agency obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Mortgage and asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	78	382
NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	5	13
NAV | Developed markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	46	277
NAV | Emerging markets equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	24	80
NAV | Real estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3	12
NAV | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value		0
NAV | Corporate obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value		0
NAV | Government and agency obligations
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value		0
NAV | Mortgage and asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
NAV | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 0	$ 0

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- Definition

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+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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