Financial Instruments - Schedule of Financial Instruments on the Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, assets	$ 96,288	$ 385,664
Gross/net financial instruments, liabilities	(7,637)	(15,408)
Designated As Hedges:
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, assets	91,981	379,101
Gross/net financial instruments, liabilities	0	0
Designated As Hedges: | Deferred charges and other assets | Interest rate contracts
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, assets	91,981	379,101
Designated As Hedges: | Deferred credits and other liabilities | Interest rate contracts
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, liabilities	0	0
Not Designated As Hedges:
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, assets	4,307	6,563
Gross/net financial instruments, liabilities	(7,637)	(15,408)
Not Designated As Hedges: | Other current assets | Commodity contracts
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, assets	2,091	4,071
Not Designated As Hedges: | Other current liabilities | Commodity contracts
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, liabilities	(7,324)	(14,584)
Not Designated As Hedges: | Deferred charges and other assets | Commodity contracts
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, assets	2,216	2,492
Not Designated As Hedges: | Deferred credits and other liabilities | Commodity contracts
Derivatives, Fair Value [Line Items]
Gross/net financial instruments, liabilities	$ (313)	$ (824)