Financial Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	$ 123,209	$ 96,288
Gross/net financial instruments, liabilities	(561)	(7,637)
Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	114,996	91,981
Gross/net financial instruments, liabilities	0	0
Designated As Hedges: | Interest rate contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	114,996	91,981
Gross/net financial instruments, liabilities	0	0
Not Designated As Hedges:
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	8,213	4,307
Gross/net financial instruments, liabilities	(561)	(7,637)
Not Designated As Hedges: | Other current assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets	8,213	2,091
Not Designated As Hedges: | Other current liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, liabilities	$ (561)	(7,324)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, assets		2,216
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts
Derivatives Fair Value [Line Items]
Gross/net financial instruments, liabilities		$ (313)