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, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 2,190	$ 2,466	$ 4,379	$ 4,932
Interest Cost		5,707	5,422	11,414	10,843
Expected Return on Plan Assets		(13,074)	(14,537)	(26,147)	(29,074)
Amortization of Prior Service Cost (Credit)		134	158	268	316
Amortization of (Gains) Losses		6,601	9,203	13,202	18,407
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	8,418	7,710	12,838	11,422
Net Periodic Benefit Cost (Income)		9,976	10,422	15,954	16,846
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		332	400	664	801
Interest Cost		2,267	2,326	4,533	4,652
Expected Return on Plan Assets		(7,340)	(7,241)	(14,680)	(14,482)
Amortization of Prior Service Cost (Credit)		(107)	(107)	(214)	(214)
Amortization of (Gains) Losses		(1,903)	212	(3,805)	424
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	4,274	9,451	10,519	16,303
Net Periodic Benefit Cost (Income)		$ (2,477)	$ 5,041	$ (2,983)	$ 7,484

[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.