Retirement Plan And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 1,297	$ 2,190	$ 3,891	$ 6,568
Interest Cost		10,629	5,707	31,887	17,121
Expected Return on Plan Assets		(16,648)	(13,074)	(49,945)	(39,221)
Amortization of Prior Service Cost (Credit)		109	134	327	403
Amortization of (Gains) Losses		(1,920)	6,601	(5,760)	19,803
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	5,378	3,470	16,134	16,308
Net Periodic Benefit Cost (Income)		(1,155)	5,028	(3,466)	20,982
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		147	332	440	996
Interest Cost		3,912	2,267	11,736	6,800
Expected Return on Plan Assets		(6,403)	(7,340)	(19,210)	(22,020)
Amortization of Prior Service Cost (Credit)		(107)	(107)	(321)	(321)
Amortization of (Gains) Losses		(2,189)	(1,903)	(6,566)	(5,708)
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	3,829	5,351	11,143	15,870
Net Periodic Benefit Cost (Income)		$ (811)	$ (1,400)	$ (2,778)	$ (4,383)

[1] The Company’s policy is to record retirement plan and other post-retirement benefit costs in the Utility segment on a volumetric basis to reflect the fact that the Utility segment experiences higher throughput of natural gas in the winter months and lower throughput of natural gas in the summer months.