Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income [Roll Forward]
Balance at Beginning of Period	$ (34,091)	$ 82,186	$ (5,640)	$ 93,372
Other Comprehensive Gains and Losses Before Reclassification	11,546	(40,588)	7,385	23,251
Amounts Reclassified From Other Comprehensive Income (Loss)	(10,759)	(33,859)	(35,049)	(108,884)
Balance at End of Period	(33,304)	7,739	(33,304)	7,739
Gains And Losses On Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Balance at Beginning of Period	36,257	146,671	64,782	157,197
Other Comprehensive Gains and Losses Before Reclassification	10,641	(40,842)	5,937	23,432
Amounts Reclassified From Other Comprehensive Income (Loss)	(10,759)	(33,859)	(34,580)	(108,659)
Balance at End of Period	36,139	71,970	36,139	71,970
Gains And Losses On Securities Available For Sale [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Balance at Beginning of Period	6,128	5,309	6,054	5,969
Other Comprehensive Gains and Losses Before Reclassification	905	254	1,448	(181)
Amounts Reclassified From Other Comprehensive Income (Loss)	0	0	(469)	(225)
Balance at End of Period	7,033	5,563	7,033	5,563
Funded Status Of The Pension And Other Post-Retirement Benefit Plans [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Balance at Beginning of Period	(76,476)	(69,794)	(76,476)	(69,794)
Other Comprehensive Gains and Losses Before Reclassification	0	0	0	0
Amounts Reclassified From Other Comprehensive Income (Loss)	0	0	0	0
Balance at End of Period	$ (76,476)	$ (69,794)	$ (76,476)	$ (69,794)