Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	$ 3,413	$ 9,897
Gross/net financial instruments, liabilities	(805)	(6,485)
Not Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets		9,897
Gross/net financial instruments, liabilities		(6,485)
Not Designated As Hedges: \| Other current assets \| Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	3,413	5,303
Not Designated As Hedges: \| Other current liabilities \| Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, liabilities	$ (805)	(6,339)
Not Designated As Hedges: \| Deferred charges and other assets \| Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets		4,594
Not Designated As Hedges: \| Deferred credits and other liabilities \| Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, liabilities		$ (146)

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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