Summary Of Significant Accounting Policies (Reclassification Out Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating Revenues	$ 375,195	$ 523,909
Purchased Gas	(42,068)	(127,091)
Operation and Maintenance	112,692	112,582
Other Income	2,418	1,183
Income Before Income Taxes	(333,459)	139,900
Income Tax Expense	144,350	(55,160)
Net Income (Loss) Available for Common Stock	(189,109)	84,740
Amount Of Gain Or (Loss) Reclassified From Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income Before Income Taxes	57,170	24,265
Income Tax Expense	(18,005)	(10,089)
Net Income (Loss) Available for Common Stock	39,165	14,176
Amount Of Gain Or (Loss) Reclassified From Accumulated Other Comprehensive Income [Member] | Commodity Contracts [Member] | Gains And Losses On Derivative Financial Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating Revenues	56,327	20,036
Purchased Gas	920	4,229
Foreign Currency Contracts [Member] | Amount Of Gain Or (Loss) Reclassified From Accumulated Other Comprehensive Income [Member] | Gains And Losses On Derivative Financial Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operation and Maintenance	$ (77)	$ 0