Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Retirement Benefits [Abstract]
Employee benefit plan obligation	$ 56	$ 58
Aggregate pension liability recorded in balance sheet	38	38
Pension expense	3	3	$ 3
Employers contribution plan expense	$ 16	$ 16	$ 14

No definition available.

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- Definition

Amount of liability, recognized in statement of financial position, for defined benefit pension plan. Excludes other postretirement benefit plan.

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

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- Definition

Amount of cost for defined contribution plan.

+ References

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- Definition

Amount of cost (reversal of cost) for pension benefits. Excludes other postretirement benefits.

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