Litigation, Claims and Contingencies - Schedule of Progression of Activity in the Asbestos Reserve (Parenthetical) (Details) - USD ($) $ in Millions	Jun. 30, 2022		Sep. 30, 2021		Jun. 30, 2021		Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2018
Ashland [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	$ 310	[1]	$ 320	[1]	$ 326	[1]	$ 335	[1]	$ 352	[1]	$ 380
Ashland [Member] | Other Current Liabilities [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	29		29
Hercules [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	220	[2]	217	[2]	$ 221	[2]	$ 229	[2]	$ 252	[2]	$ 282
Hercules [Member] | Other Current Liabilities [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	$ 18		$ 18

[1] Included $29 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of June 30, 2022 and September 30, 2021.

[2] Included $18 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of June 30, 2022 and September 30, 2021.