Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 31,712	$ 60,881
Liability for Royalty and Working Interests	86,206	31,483
Other Accruals and Current Liabilities	257,327	194,169
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	64,720	42,541
Regulatory Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	31,293	60,860
Other Accruals [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	57,634	43,877
Non-Qualified [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-Qualified Benefit Plan Liability	77,200	95,800	$ 98,100
Non-Qualified [Member] | Current [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-Qualified Benefit Plan Liability	$ 17,474	$ 15,408	$ 14,500