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Reportable Segment Information - Summary of Financial Information for Each Reportable Segment (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Loss on sale of divestiture business	$ 115	$ (6)	$ (42)
Accelerated depreciation	57
Specialty Additives facility [Member]
Segment Reporting Information [Line Items]
Impairment charge		$ 4
Discontinued Operations, Held-for-sale [Member]
Segment Reporting Information [Line Items]
Impairment charge	99
Loss on sale of divestiture business	(8)
Personal Care [Member]
Segment Reporting Information [Line Items]
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]		Operating Income (Loss)
Capital project impairment	11
Accelerated depreciation	2
Specialty Additives [Member]
Segment Reporting Information [Line Items]
Accelerated depreciation	$ 55