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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 2,190	$ 2,466	$ 6,568	$ 7,399
Interest Cost		5,707	5,422	17,121	16,265
Expected Return on Plan Assets		(13,074)	(14,537)	(39,221)	(43,611)
Amortization of Prior Service Cost (Credit)		134	158	403	473
Amortization of (Gains) Losses		6,601	9,203	19,803	27,610
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	3,470	2,772	16,308	14,194
Net Periodic Benefit Cost (Income)		5,028	5,484	20,982	22,330
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		332	400	996	1,202
Interest Cost		2,267	2,326	6,800	6,977
Expected Return on Plan Assets		(7,340)	(7,241)	(22,020)	(21,723)
Amortization of Prior Service Cost (Credit)		(107)	(107)	(321)	(321)
Amortization of (Gains) Losses		(1,903)	212	(5,708)	636
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	5,351	6,639	15,870	22,942
Net Periodic Benefit Cost (Income)		$ (1,400)	$ 2,229	$ (4,383)	$ 9,713

[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.