Retirement Benefits - Schedule of Accumulated and Project Benefit Obligations (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Sep. 30, 2025 |
|---|---|---|
| Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract] | ||
| Projected benefit obligation | $ 300 | $ 2,185 |
| Fair value of plan assets | 22 | 1,842 |
| Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract] | ||
| Accumulated benefit obligation | 231 | 274 |
| Fair value of plan assets | $ 2 | $ 9 |
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- Definition Amount of plan asset for defined benefit pension plan with projected benefit obligation in excess of plan assets. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- References No definition available.
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- Definition Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of projected benefit obligation for defined benefit pension plan with accumulated benefit obligation in excess of plan assets. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- References No definition available.
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