Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ (5,640)	$ 93,372
Other Comprehensive Gains and Losses Before Reclassifications	15,327	29,750
Amounts Reclassified From Other Comprehensive Loss	(39,810)	(128,762)
Ending balance	(30,123)	(5,640)
Gains and Losses on Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	64,782	157,197
Other Comprehensive Gains and Losses Before Reclassifications	3,338	41,845
Amounts Reclassified From Other Comprehensive Loss	(47,319)	(134,260)
Ending balance	20,801	64,782
Gains and Losses on Securities Available for Sale [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	6,054	5,969
Other Comprehensive Gains and Losses Before Reclassifications	2,503	932
Amounts Reclassified From Other Comprehensive Loss	(995)	(847)
Ending balance	7,562	6,054
Funded Status of the Pension and Other Post-Retirement Benefit Plans [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(76,476)	(69,794)
Other Comprehensive Gains and Losses Before Reclassifications	9,486	(13,027)
Amounts Reclassified From Other Comprehensive Loss	8,504	6,345
Ending balance	$ (58,486)	$ (76,476)