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Pension Plans and Other Postretirement Benefits - Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2024 USD ($)
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | $ 3,141
Fair value of plan assets at end of year | 3,203
Level 3 |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 444
Net Purchases (Sales) | (10)
Realized and unrealized gains (losses) | 51
Fair value of plan assets at end of year | 485
Real estate partnerships |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 29
Fair value of plan assets at end of year | 31
Real estate partnerships | Level 3 |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 22
Net Purchases (Sales) | 3
Realized and unrealized gains (losses) | 1
Fair value of plan assets at end of year | 26
Private equity/debt |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 235
Fair value of plan assets at end of year | 265
Private equity/debt | Level 3 |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 235
Net Purchases (Sales) | 5
Realized and unrealized gains (losses) | 25
Fair value of plan assets at end of year | 265
Hedge funds |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 285
Fair value of plan assets at end of year | 267
Hedge funds | Level 3 |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 178
Net Purchases (Sales) | (18)
Realized and unrealized gains (losses) | 24
Fair value of plan assets at end of year | 184
Guaranteed deposit fund |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 9
Fair value of plan assets at end of year | 10
Guaranteed deposit fund | Level 3 |
Defined Benefit Plan Disclosure [Line Items] |
Fair value of plan assets at beginning of year | 9
Net Purchases (Sales) | 0
Realized and unrealized gains (losses) | 1
Fair value of plan assets at end of year | $ 10

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- Definition Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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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 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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