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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 3,012	$ 2,997	$ 9,036	$ 8,990
Interest Cost		10,304	10,893	30,913	32,681
Expected Return on Plan Assets		(14,904)	(14,993)	(44,712)	(44,980)
Amortization of Prior Service Cost (Credit)		46	52	137	157
Amortization of Losses		9,032	9,002	27,097	27,005
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	[1]	88	456	8,434	10,591
Net Periodic Benefit Cost		7,578	8,407	30,905	34,444
Other Post-Retirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		673	735	2,019	2,204
Interest Cost		4,821	5,327	14,464	15,981
Expected Return on Plan Assets		(8,522)	(9,356)	(25,566)	(28,067)
Amortization of Prior Service Cost (Credit)		(478)	(534)	(1,435)	(1,604)
Amortization of Losses		1,037	661	3,111	1,984
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	[1]	4,739	5,325	17,055	19,314
Net Periodic Benefit Cost		$ 2,270	$ 2,158	$ 9,648	$ 9,812

[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.