Financial Information by Segment - Schedule of Details of Certain Items (Detail) - Certain Items [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting [Line Items]
Global restructuring activities (Note I)	$ (42)	$ (3)	$ (57)	$ (6)
Employee benefit plan settlement and other charges (Note E)	(30)		(30)
Legal and environmental matters and reserves (Note F)	(5)		(5)	(6)
Acquisition and integration-related charges (Note C)	(1)		(2)
Other certain items				(1)
Total certain items	$ (78)	$ (3)	$ (94)	$ (13)

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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+ Details