Financial Instruments (Schedule Of Derivatives And Hedged Items In Fair Value Hedging Relationships) (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2016 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) on the Derivative Recognized in the Consolidated Statement of Income	$ 5,403
Amount of Gain or (Loss) on the Hedged Item Recognized in the Consolidated Statement of Income	(5,403)
Operating Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) on the Derivative Recognized in the Consolidated Statement of Income	5,557
Amount of Gain or (Loss) on the Hedged Item Recognized in the Consolidated Statement of Income	(5,557)
Purchased Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) on the Derivative Recognized in the Consolidated Statement of Income	(154)
Amount of Gain or (Loss) on the Hedged Item Recognized in the Consolidated Statement of Income	$ 154