Income Taxes (Significant Components Of Deferred Tax Liabilities And Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Deferred Tax Liabilities [Abstract]
Property, Plant and Equipment	$ 954,757	$ 920,692
Pension and Other Post-Retirement Benefit Costs	30,132	23,240
Other	48,893	35,081
Total Deferred Tax Liabilities	1,033,782	979,013
Deferred Tax Assets [Abstract]
Unrealized Hedging Losses	(215,187)	(170,155)
Tax Loss and Credit Carryforwards	(50,686)	(120,725)
Pension and Other Post-Retirement Benefit Costs	(37,250)	(53,765)
Other	(32,430)	(31,593)
Total Gross Deferred Tax Assets	(335,553)	(376,238)
Valuation Allowance	0	57,645	$ 63,205	$ 0
Total Deferred Tax Assets	(335,553)	(318,593)
Total Net Deferred Income Taxes	$ 698,229	$ 660,420