Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at Beginning of Period	$ (52,155)	$ (67,750)
Other Comprehensive Gains and Losses Before Reclassifications	376	31,774
Amounts Reclassified From Other Comprehensive Income (Loss)	(5,321)	14,723
Cumulative Effect of Adoption of Authoritative Guidance for Hedging	950
Reclassification Adjustment for the Cumulative Effect of Adoption of Authoritative Guidance for Financial Assets and Liabilities		(7,437)
Balance at End of Period	(56,150)	(28,690)
Gains And Losses On Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at Beginning of Period	34,675
Other Comprehensive Gains and Losses Before Reclassifications	376
Amounts Reclassified From Other Comprehensive Income (Loss)	(5,321)
Cumulative Effect of Adoption of Authoritative Guidance for Hedging	950
Balance at End of Period	30,680
Gains And Losses On Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at Beginning of Period		(28,611)
Other Comprehensive Gains and Losses Before Reclassifications		31,774
Amounts Reclassified From Other Comprehensive Income (Loss)		14,723
Reclassification Adjustment for the Cumulative Effect of Adoption of Authoritative Guidance for Financial Assets and Liabilities		0
Balance at End of Period		17,886
Gains And Losses On Securities Available For Sale [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at Beginning of Period	0	7,437
Other Comprehensive Gains and Losses Before Reclassifications	0	0
Amounts Reclassified From Other Comprehensive Income (Loss)	0	0
Cumulative Effect of Adoption of Authoritative Guidance for Hedging	0
Reclassification Adjustment for the Cumulative Effect of Adoption of Authoritative Guidance for Financial Assets and Liabilities		(7,437)
Balance at End of Period	0	0
Funded Status Of The Pension And Other Post-Retirement Benefit Plans [Member]
Accumulated Other Comprehensive Loss [Roll Forward]
Balance at Beginning of Period	(86,830)	(46,576)
Other Comprehensive Gains and Losses Before Reclassifications	0	0
Amounts Reclassified From Other Comprehensive Income (Loss)	0	0
Cumulative Effect of Adoption of Authoritative Guidance for Hedging	0
Reclassification Adjustment for the Cumulative Effect of Adoption of Authoritative Guidance for Financial Assets and Liabilities		0
Balance at End of Period	$ (86,830)	$ (46,576)