Retirement Plan And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 1,297	$ 2,190	$ 2,594	$ 4,379
Interest Cost		10,629	5,707	21,258	11,414
Expected Return on Plan Assets		(16,648)	(13,074)	(33,297)	(26,147)
Amortization of Prior Service Cost (Credit)		109	134	218	268
Amortization of (Gains) Losses		(1,920)	6,601	(3,840)	13,202
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	5,378	8,418	10,756	12,838
Net Periodic Benefit Cost (Income)		(1,155)	9,976	(2,311)	15,954
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		147	332	293	664
Interest Cost		3,912	2,267	7,824	4,533
Expected Return on Plan Assets		(6,403)	(7,340)	(12,806)	(14,680)
Amortization of Prior Service Cost (Credit)		(107)	(107)	(214)	(214)
Amortization of (Gains) Losses		(2,189)	(1,903)	(4,378)	(3,805)
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	3,493	4,274	7,314	10,519
Net Periodic Benefit Cost (Income)		$ (1,147)	$ (2,477)	$ (1,967)	$ (2,983)

[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.