Retirement Plan And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 3,012		$ 2,997
Interest Cost	10,304		10,893
Expected Return on Plan Assets	(14,904)		(14,993)
Amortization of Prior Service Cost (Credit)	46		52
Amortization of Losses	9,032		9,002
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	1,292	[1]	1,578	[1]
Net Periodic Benefit Cost	8,782		9,529
Other Post-Retirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	673		735
Interest Cost	4,821		5,327
Expected Return on Plan Assets	(8,522)		(9,356)
Amortization of Prior Service Cost (Credit)	(478)		(534)
Amortization of Losses	1,037		661
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	4,920	[1]	6,060	[1]
Net Periodic Benefit Cost	$ 2,451		$ 2,893

[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.