Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 39,662	$ 31,293
Reserve for Gas Replacement	6,554	32,364
Liability for Royalty and Working Interests	14,365	86,206
Other Accruals and Current Liabilities	257,923	257,327
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	39,232	64,720
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	106,835	0
Other Accruals [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	40,355	57,634
Non-Qualified [Member] | Current [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-Qualified Benefit Plan Liability	$ 17,474	$ 17,474