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, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 1,049	$ 1,297	$ 2,098	$ 2,594
Interest Cost		10,890	10,629	21,779	21,258
Expected Return on Plan Assets		(17,086)	(16,648)	(34,172)	(33,297)
Amortization of Prior Service Cost (Credit)		91	109	181	218
Amortization of (Gains) Losses		(335)	(1,920)	(669)	(3,840)
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	4,057	5,378	8,116	10,756
Net Periodic Benefit Cost (Income)		(1,334)	(1,155)	(2,667)	(2,311)
Other Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service Cost		109	147	217	293
Interest Cost		3,890	3,912	7,780	7,824
Expected Return on Plan Assets		(6,660)	(6,403)	(13,321)	(12,806)
Amortization of Prior Service Cost (Credit)		(107)	(107)	(214)	(214)
Amortization of (Gains) Losses		(567)	(2,189)	(1,133)	(4,378)
Net Amortization and Deferral for Regulatory Purposes (Including Volumetric Adjustments)	[1]	1,769	3,493	4,008	7,314
Net Periodic Benefit Cost (Income)		$ (1,566)	$ (1,147)	$ (2,663)	$ (1,967)

[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.