Summary Of Significant Accounting Policies (Components Of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ (55,060)	$ (625,733)
Other Comprehensive Gains and Losses Before Reclassifications	136,681	216,216
Amounts Reclassified From Other Comprehensive Income	(14,240)	115,771
Ending balance	67,381	(293,746)
Gains and Losses on Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	4,623	(572,163)
Other Comprehensive Gains and Losses Before Reclassifications	136,681	216,216
Amounts Reclassified From Other Comprehensive Income	(14,240)	115,771
Ending balance	127,064	(240,176)
Funded Status of the Pension and Other Post-Retirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(59,683)	(53,570)
Other Comprehensive Gains and Losses Before Reclassifications	0	0
Amounts Reclassified From Other Comprehensive Income	0	0
Ending balance	$ (59,683)	$ (53,570)