Retirement Plan And Other Post-Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 2,928	$ 3,012
Interest Cost		10,579	10,304
Expected Return on Plan Assets		(14,842)	(14,904)
Amortization of Prior Service Cost (Credit)		308	46
Amortization of Losses		8,062	9,032
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	[1]	1,906	1,292
Net Periodic Benefit Cost		8,941	8,782
Other Post-Retirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		583	673
Interest Cost		5,096	4,821
Expected Return on Plan Assets		(7,883)	(8,522)
Amortization of Prior Service Cost (Credit)		(228)	(478)
Amortization of Losses		1,382	1,037
Net Amortization and Deferral For Regulatory Purposes (Including Volumetric Adjustments)	[1]	4,121	4,920
Net Periodic Benefit Cost		$ 3,071	$ 2,451

[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.