Retirement Plan And Other Post-Retirement Benefits (Schedule Of Benefit Obligation And Plan Assets And Funded Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Other Post-Retirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 1,176		$ 1,004
Interest Cost	4,803		5,329
Expected Return on Plan Assets	(8,218)		(7,243)
Amortization of Prior Service Cost	(534)		(534)
Amortization of Transition Amount	2		3
Amortization of Losses	5,223		6,014
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	2,703	[1]	2,132	[1]
Net Periodic Benefit Cost	5,155		6,705
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	3,961		3,551
Interest Cost	9,124		10,381
Expected Return on Plan Assets	(14,336)		(14,925)
Amortization of Prior Service Cost	60		67
Amortization of Transition Amount	0		0
Amortization of Losses	13,194		9,904
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	(3,682)	[1]	(1,802)	[1]
Net Periodic Benefit Cost	$ 8,321		$ 7,176

[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.