Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
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| Components of net periodic benefit cost for postretirement benefit plans | ||
| Net periodic benefit cost | $ 1 | $ 2 |
| Pension Benefit Plans | ||
| Components of net periodic benefit cost for postretirement benefit plans | ||
| Service cost | 6 | 5 |
| Interest cost | 18 | 18 |
| Expected return on assets | (19) | (20) |
| Amortization — losses (gains), net | 0 | 1 |
| Amortization — prior service credit, net | 0 | (1) |
| Settlement and curtailment gain | 0 | 0 |
| Net periodic benefit cost | 5 | 3 |
| Other Benefit Plans | ||
| Components of net periodic benefit cost for postretirement benefit plans | ||
| Service cost | 1 | 0 |
| Interest cost | 2 | 1 |
| Expected return on assets | 0 | 0 |
| Amortization — losses (gains), net | (1) | 0 |
| Amortization — prior service credit, net | (1) | (1) |
| Settlement and curtailment gain | 0 | (11) |
| Net periodic benefit cost | $ 1 | $ (11) |
| X | ||||||||||
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from settlement and curtailment. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- References No definition available.
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