Retirement Plan And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 3,961		$ 3,551		$ 11,884		$ 10,652
Interest Cost	9,124		10,381		27,373		31,144
Expected Return on Plan Assets	(14,336)		(14,925)		(43,009)		(44,776)
Amortization of Prior Service Cost	60		67		179		202
Amortization of Transition Amount	0		0		0		0
Amortization of Losses	13,194		9,904		39,582		29,711
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	(3,854)	[1]	(2,252)	[1]	(5,813)	[1]	(1,896)	[1]
Net Periodic Benefit Cost	8,149		6,726		30,196		25,037
Other Post-Retirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1,176		1,004		3,529		3,012
Interest Cost	4,803		5,329		14,409		15,986
Expected Return on Plan Assets	(8,218)		(7,243)		(24,654)		(21,728)
Amortization of Prior Service Cost	(534)		(534)		(1,604)		(1,604)
Amortization of Transition Amount	2		3		6		8
Amortization of Losses	5,223		6,014		15,669		18,043
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	2,393	[1]	718	[1]	11,555	[1]	7,993	[1]
Net Periodic Benefit Cost	$ 4,845		$ 5,291		$ 18,910		$ 21,710

[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.