Financial Information by Segment - Schedule of Income (Loss) from Continuing Operations before Income Taxes and Equity in Earnings of Affiliated Companies for Unallocated and Other (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Interest expense	$ (19)	$ (19)	$ (56)	$ (62)
Less: Equity in earnings of affiliated companies, net of tax	1	2	5	5
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Interest expense	(19)	(19)	(56)	(62)
Unallocated corporate costs	(13)	(16)	(39)	(51)
General unallocated income (expense)	6	6	22	34
Less: Equity in earnings of affiliated companies, net of tax	1	2	5	5
Income from continuing operations before income taxes and equity in earnings of affiliated companies	(30)	(33)	(91)	(140)
Certain Items [Member]
Segment Reporting Information [Line Items]
Global restructuring activities	(3)	(1)	(6)	(13)
Legal and environmental matters and reserves			(6)	(1)
Other certain items		1	(1)	1
Total certain items	$ (3)	(2)	$ (13)	(56)
Certain Items [Member] | Argentina [Member]
Segment Reporting Information [Line Items]
Controlled currency devaluation and other losses		$ (2)		$ (43)