Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (513,597)	$ (114,757)
Other Comprehensive Gains and Losses Before Reclassifications	(755,831)	(472,553)
Amounts Reclassified From Other Comprehensive Income (Loss)	649,502	73,713
Other Post-Retirement Adjustment for Regulatory Proceeding After Tax	(5,807)
Ending balance	(625,733)	(513,597)
Gains and Losses on Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(449,962)	(24,865)
Other Comprehensive Gains and Losses Before Reclassifications	(763,223)	(486,343)
Amounts Reclassified From Other Comprehensive Income (Loss)	641,022	61,246
Other Post-Retirement Adjustment for Regulatory Proceeding After Tax	0
Ending balance	(572,163)	(449,962)
Funded Status of the Pension and Other Post-Retirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(63,635)	(89,892)
Other Comprehensive Gains and Losses Before Reclassifications	7,392	13,790
Amounts Reclassified From Other Comprehensive Income (Loss)	8,480	12,467
Other Post-Retirement Adjustment for Regulatory Proceeding After Tax	(5,807)
Ending balance	$ (53,570)	$ (63,635)