Litigation, Claims and Contingencies - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended				12 Months Ended
	Jun. 30, 2022 USD ($) ServiceStationProperty Facility WasteTreatmentOrDisposalSite		Jun. 30, 2022 USD ($) ServiceStationProperty Facility WasteTreatmentOrDisposalSite		Jun. 30, 2021 USD ($)		Sep. 30, 2021 USD ($)		Sep. 30, 2020 USD ($)		Sep. 30, 2019 USD ($)		Sep. 30, 2018 USD ($)
Asbestos litigation cost projection [Abstract]
Number of Years Included in Asbestos Assumption			40 years
Environmental Remediation Costs Recognized [Abstract]
Number of waste treatment or disposal sites were company is identified as a potentially responsible party under the superfund or similar state laws | WasteTreatmentOrDisposalSite	76		76
Number of current and former operating facilities subject to various environmental laws | Facility	111		111
Total number of service station properties subject to various environmental laws | ServiceStationProperty	1,225		1,225
Number of service stations being actively remediated | ServiceStationProperty	17		17
Accrual for environmental loss contingencies	$ 226		$ 226		$ 205		$ 207		$ 200
Accrued environmental loss contingencies, noncurrent	171		171				152
Recorded third-party environmental recoveries receivable	20		20				16
Recorded third-party environmental recoveries, noncurrent	$ 17		17				13
Environmental exit costs, reasonably possible additional loss			$ 480
Maximum reserve for remediation reserve related to any one site (in hundredths)	12.00%		12.00%
Ashland [Member]
Asbestos reserve [Roll Forward]
Increase (decrease) in asbestos related reserve			$ 16		12		12		13		$ 1
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable	$ 102	[1]	102	[1]	102	[1]	100	[1]	103	[1]	123	[1]	$ 140
Receivable adjustment	7
Asbestos litigation cost projection [Abstract]
Possible total future litigation defense and claim settlement costs	456		456
Total reserves for asbestos claims	310	[2]	310	[2]	326	[2]	320	[2]	335	[2]	352	[2]	380
Hercules [Member]
Asbestos reserve [Roll Forward]
Increase (decrease) in asbestos related reserve	15		15		8		8		(3)		(10)
Movement in Loss Contingency Receivable, Increase (Decrease) [Roll Forward]
Insurance receivable	53	[3]	53	[3]	48	[3]	47	[3]	47	[3]	49	[3]	54
Receivable adjustment			7
Asbestos litigation cost projection [Abstract]
Possible total future litigation defense and claim settlement costs	317		317
Total reserves for asbestos claims	$ 220	[4]	$ 220	[4]	$ 221	[4]	$ 217	[4]	$ 229	[4]	$ 252	[4]	$ 282

[1] Includes $12 million classified in accounts receivable on the Condensed Consolidated Balance Sheets as of June 30, 2022 and September 30, 2021.

[2] 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.

[3] Includes $3 million and $1 million classified in accounts receivable on the Condensed Consolidated Balance Sheets as of June 30, 2022 and September 30, 2021, respectively.

[4] 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.