Financial Instruments (Schedule Of Derivatives And Hedged Items In Fair Value Hedging Relationships) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) on the Derivative Recognized in the Consolidated Statement of Income	$ (12,503)
Amount of Gain or (Loss) on the Hedged Item Recognized in the Consolidated Statement of Income	12,503
Operating Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) on the Derivative Recognized in the Consolidated Statement of Income	(12,549)
Amount of Gain or (Loss) on the Hedged Item Recognized in the Consolidated Statement of Income	12,549
Purchased Gas [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) on the Derivative Recognized in the Consolidated Statement of Income	46
Amount of Gain or (Loss) on the Hedged Item Recognized in the Consolidated Statement of Income	$ (46)