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.

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Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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-Topic 842
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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Lessee Lease Description [Line Items]
Short term lease costs	$ 7	$ 5	$ 5
Variable lease cost	$ 2	$ 1	$ 1
Minimum [Member]
Lessee Lease Description [Line Items]
Lease term	1 year
Maximum [Member]
Lessee Lease Description [Line Items]
Lease term	16 years
Lease extension period	15 years
Maximum [Member] \| Land [Member]
Lessee Lease Description [Line Items]
Lease term	79 years