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Restructuring - Restructuring Activities and Related Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Restructuring Cost and Reserve [Line Items]
Reserve balance	$ 1	$ 0
Charges	11	13	$ 4
Costs charged against assets		(6)
Cash paid	(4)	(6)
Reserve balance	8	1	0
Severance and Employee Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance	0	0
Charges	10	5
Cash paid	(3)	(5)
Reserve balance	7	0	0
Accelerated Depreciation on Assets [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance	0	0
Charges		6
Costs charged against assets		(6)
Reserve balance	0	0	0
Other [Member]
Restructuring Cost and Reserve [Line Items]
Reserve balance	1	0
Charges	1	2
Cash paid	(1)	(1)
Reserve balance	$ 1	$ 1	$ 0

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Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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