Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 75,340	$ (54,864)	$ (55,060)	$ (625,733)
Other Comprehensive Gains and Losses Before Reclassifications	(15,850)	47,359	172,249	488,726
Amounts Reclassified From Other Comprehensive Income (Loss)	(54,440)	(41,879)	(112,139)	87,623
Ending balance	5,050	(49,384)	5,050	(49,384)
Gains and Losses on Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	135,023	(1,294)	4,623	(572,163)
Other Comprehensive Gains and Losses Before Reclassifications	(15,850)	47,359	172,249	488,726
Amounts Reclassified From Other Comprehensive Income (Loss)	(54,440)	(41,879)	(112,139)	87,623
Ending balance	64,733	4,186	64,733	4,186
Funded Status of the Pension and Other Post-Retirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(59,683)	(53,570)	(59,683)	(53,570)
Other Comprehensive Gains and Losses Before Reclassifications	0	0	0	0
Amounts Reclassified From Other Comprehensive Income (Loss)	0	0	0	0
Ending balance	$ (59,683)	$ (53,570)	$ (59,683)	$ (53,570)