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		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Interest expense	$ (19)	$ (21)	$ (37)	$ (43)
Less: Equity in earnings of affiliated companies, net of tax	3	2	4	3
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Interest expense	(19)	(21)	(37)	(43)
Unallocated corporate costs	(13)	(18)	(26)	(35)
General unallocated income (expense)	9	15	16	28
Less: Equity in earnings of affiliated companies, net of tax	3	2	4	3
Income from continuing operations before income taxes and equity in earnings of affiliated companies	(30)	(38)	(61)	(107)
Certain Items [Member]
Segment Reporting Information [Line Items]
Legal and environmental matters and reserves	(1)	(1)	(6)	(1)
Global restructuring activities	(3)	(3)	(3)	(12)
Other certain items			(1)
Total certain items	$ (4)	(12)	$ (10)	(54)
Certain Items [Member] | Argentina [Member]
Segment Reporting Information [Line Items]
Controlled currency devaluation and other losses		$ (8)		$ (41)