Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 93,372	$ (3,979)
Other Comprehensive Gains and Losses Before Reclassifications	29,750	198,491
Amounts Reclassified From Other Comprehensive Income (Loss)	(128,762)	(101,140)
Ending balance	(5,640)	93,372
Gains and Losses on Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	157,197	43,659
Other Comprehensive Gains and Losses Before Reclassifications	41,845	220,146
Amounts Reclassified From Other Comprehensive Income (Loss)	(134,260)	(106,608)
Ending balance	64,782	157,197
Gains and Losses on Securities Available for Sale [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	5,969	8,382
Other Comprehensive Gains and Losses Before Reclassifications	932	(2,039)
Amounts Reclassified From Other Comprehensive Income (Loss)	(847)	(374)
Ending balance	6,054	5,969
Funded Status of the Pension and Other Post-Retirement Benefit Plans [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(69,794)	(56,020)
Other Comprehensive Gains and Losses Before Reclassifications	(13,027)	(19,616)
Amounts Reclassified From Other Comprehensive Income (Loss)	6,345	5,842
Ending balance	$ (76,476)	$ (69,794)