Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Income Taxes [Line Items]
Other tax credit carryforwards	$ 136,000,000
Undistributed earnings	1,359,000,000
Unrecognized tax benefits	20,000,000	$ 159,000,000	$ 21,000,000	$ 23,000,000
Unrecognized tax benefits, offset against deferred tax assets	14,000,000
Non cash income tax expense (benefit)	152,000,000
Accruals for penalties and interest	5,000,000
Total penalties and interest	2,000,000	2,000,000	1,000,000
Favorable impact on tax provision	$ 20,000,000
Earliest Tax Year [Member] | United States Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2020
Latest Tax Year [Member] | United States Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2022
Purification Solutions [Member]
Income Taxes [Line Items]
Income tax benefit from tax loss related to divestiture	$ 137,000,000	137,000,000
Other Liabilities [Member]
Income Taxes [Line Items]
Unrecognized tax benefits, recorded	6,000,000
Maximum [Member]
Income Taxes [Line Items]
Other tax credit carryforwards	1,000,000
Foreign Jurisdictions [Member]
Income Taxes [Line Items]
NOLs	$ 24,000,000
Foreign Jurisdictions [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2006
Foreign Jurisdictions [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2022
State Tax Authorities [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2010
State Tax Authorities [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination	2022
U.S. Defined Benefit Plans [Member]
Income Taxes [Line Items]
Increased/(decreased) valuation in allowance	$ (498,000,000)
U.S. Defined Benefit Plans [Member] | Maximum [Member]
Income Taxes [Line Items]
Increased/(decreased) valuation in allowance		580,000,000	470,000,000
U.S. Defined Benefit Plans [Member] | Minimum [Member]
Income Taxes [Line Items]
Increased/(decreased) valuation in allowance		$ (82,000,000)	$ 110,000,000