Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (114,757)	$ (52,155)
Other Comprehensive Gains and Losses Before Reclassifications	(472,553)	(7,573)
Amounts Reclassified From Other Comprehensive Income (Loss)	73,713	(55,979)
Cumulative Effect of Adoption of Authoritative Guidance for Hedging		950
Ending balance	(513,597)	(114,757)
Gains and Losses on Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(24,865)	34,675
Other Comprehensive Gains and Losses Before Reclassifications	(486,343)	7,284
Amounts Reclassified From Other Comprehensive Income (Loss)	61,246	(67,774)
Cumulative Effect of Adoption of Authoritative Guidance for Hedging		950
Ending balance	(449,962)	(24,865)
Funded Status of the Pension and Other Post-Retirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(89,892)	(86,830)
Other Comprehensive Gains and Losses Before Reclassifications	13,790	(14,857)
Amounts Reclassified From Other Comprehensive Income (Loss)	12,467	11,795
Cumulative Effect of Adoption of Authoritative Guidance for Hedging		0
Ending balance	$ (63,635)	$ (89,892)