Summary of Significant Accounting Policies - Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenues		$ 2,173,771	$ 2,186,046	$ 1,742,659
Total Before Income Tax		641,399	682,650	478,329
Income Tax Expense		(164,533)	(116,629)	(114,682)
Net of Tax		476,866	566,021	$ 363,647
Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Before Income Tax		(90,330)	(893,635)
Income Tax Expense		6,217	244,133
Net of Tax		(84,113)	(649,502)
Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Loss | Amortization of Prior Year Funded Status of the Pension and Other Post-Retirement Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Service Cost	[1]	(82)	(103)
Net Actuarial Loss	[1]	(1,592)	(10,951)
Commodity Contracts | Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Loss | Gains (Losses) on Derivative Financial Instrument Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenues		(88,015)	(882,594)
Foreign Currency Contracts | Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Loss | Gains (Losses) on Derivative Financial Instrument Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenues		$ (641)	$ 13

[1] These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost. Refer to Note K — Retirement Plan and Other Post-Retirement Benefits for additional details.