Postretirement Benefit Plans (Postretirement Amounts Recognized in AOCI) (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|---|---|---|---|
| Pension Benefits [Member] | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Net actuarial gains (losses) | $ 1 | $ (46) | |
| Prior service credit | 9 | 12 | |
| Total postretirement amounts recognized in accumulated other comprehensive loss | 10 | (34) | $ (18) |
| Other Benefits [Member] | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Net actuarial gains (losses) | 40 | 37 | |
| Prior service credit | 28 | 31 | |
| Total postretirement amounts recognized in accumulated other comprehensive loss | $ 68 | $ 68 | $ 72 |
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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit). Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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. No definition available.
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