Summary Of Significant Accounting Policies (Reclassification Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenues		$ 2,186,046	$ 1,742,659	$ 1,546,291
Purchased Gas		392,093	171,827	233,890
Income (Loss) Before Income Taxes		682,650	478,329	(105,033)
Income Tax Expense		(116,629)	(114,682)	(18,739)
Net Income (Loss) Available for Common Stock		566,021	363,647	$ (123,772)
Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Income (Loss) Before Income Taxes		(893,635)	(99,940)
Income Tax Expense		244,133	26,227
Net Income (Loss) Available for Common Stock		(649,502)	(73,713)
Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Income (Loss) [Member] | Amortization of Prior Year Funded Status of Pension and Other Post-Retirement Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of Prior Service Cost	[1]	$ (103)	$ (208)
Amortization of Prior Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Income (Deductions)	Other Income (Deductions)
Recognition of Net Actuarial Loss	[1]	$ (10,951)	$ (16,021)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Income (Loss) [Member] | Commodity Contracts [Member] | Gains and Losses on Derivative Financial Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenues		$ (882,594)	$ (83,973)
Foreign Currency Contracts [Member] | Amount of Gain or (Loss) Reclassified From Accumulated Other Comprehensive Income (Loss) [Member] | Gains and Losses on Derivative Financial Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Operating Revenues		$ 13	$ 262

[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.