Restructuring Activities - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Life Sciences [Member]
Restructuring Cost And Reserve [Line Items]
Accelerated depreciation		$ 8		$ 21
Specialty Additives [Member]
Restructuring Cost And Reserve [Line Items]
Accelerated depreciation		19	$ 3	19
Fiscal 2025 and 2023 Restructuring Severance Costs [Member] \| Life Sciences, Personal Care and Specialty Additives [Member]
Restructuring Cost And Reserve [Line Items]
Accelerated depreciation		$ 27		$ 40
Fiscal 2025 and 2023 Restructuring Severance Costs [Member] \| Specialty Additives [Member]
Restructuring Cost And Reserve [Line Items]
Accelerated depreciation	$ 0		$ 4

- Definition

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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