Litigation, Claims and Contingencies - Schedule of Progression of Activity in the Asbestos Reserve (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended				12 Months Ended
		Jun. 30, 2022	Jun. 30, 2022		Jun. 30, 2021		Sep. 30, 2021		Sep. 30, 2020		Sep. 30, 2019
Ashland [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve - beginning of year			$ 320	[1]	$ 335	[1]	$ 335	[1]	$ 352	[1]	$ 380
Reserve adjustment			16		12		12		13		1
Amounts paid			(26)		(21)		(27)		(30)		(29)
Asbestos reserve - end of period	[1]	$ 310	310		326		320		335		352
Hercules [Member]
Asbestos reserve [Roll Forward]
Asbestos reserve - beginning of year			217	[2]	229	[2]	229	[2]	252	[2]	282
Reserve adjustment		15	15		8		8		(3)		(10)
Amounts paid			(12)		(16)		(20)		(20)		(20)
Asbestos reserve - end of period	[2]	$ 220	$ 220		$ 221		$ 217		$ 229		$ 252

[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.