Retirement Plan And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2014		Mar. 31, 2013
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 2,997		$ 3,961		$ 5,993		$ 7,923
Interest Cost	10,893		9,124		21,787		18,249
Expected Return on Plan Assets	(14,993)		(14,336)		(29,986)		(28,673)
Amortization of Prior Service Cost (Credit)	52		60		105		119
Amortization of Transition Amount	0		0		0		0
Amortization of Losses	9,002		13,194		18,003		26,388
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	8,557	[1]	1,724	[1]	10,135	[1]	(1,958)	[1]
Net Periodic Benefit Cost	16,508		13,727		26,037		22,048
Other Post-Retirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	735		1,176		1,469		2,352
Interest Cost	5,327		4,803		10,654		9,606
Expected Return on Plan Assets	(9,356)		(8,218)		(18,712)		(16,436)
Amortization of Prior Service Cost (Credit)	(534)		(534)		(1,069)		(1,069)
Amortization of Transition Amount	0		2		0		4
Amortization of Losses	661		5,223		1,323		10,446
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	7,928	[1]	6,459	[1]	13,988	[1]	9,162	[1]
Net Periodic Benefit Cost	$ 4,761		$ 8,911		$ 7,653		$ 14,065

[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.