Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Sep. 30, 2021
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 31,959	$ 60,860
Reserve for Gas Replacement	12,336	33,669
Liability for Royalty and Working Interests	63,755	31,483
Other Accruals and Current Liabilities	254,383	194,169
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	59,849	42,541
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	21,775	0
Other Accruals [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	61,483	43,723
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	154	154
Non-Qualified [Member] | Current [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-Qualified Benefit Plan Liability	$ 15,408	$ 15,408