Litigation, Claims and Contingencies - Schedule of Progression of Activity in the Asbestos Reserve (Parenthetical) (Details) - USD ($) $ in Millions	Mar. 31, 2023		Sep. 30, 2022		Mar. 31, 2022		Sep. 30, 2021		Sep. 30, 2020		Sep. 30, 2019
Ashland [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	$ 285	[1]	$ 305	[1]	$ 301	[1]	$ 320	[1]	$ 335	[1]	$ 352
Ashland [Member] | Other Current Liabilities [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	29		29
Hercules [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve	205	[2]	213	[2]	$ 207	[2]	$ 217	[2]	$ 229	[2]	$ 252
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 March 31, 2023 and September 30, 2022.

[2] Included $18 million classified in accrued expenses and other liabilities on the Condensed Consolidated Balance Sheets as of March 31, 2023 and September 30, 2022.