Summary Of Significant Accounting Policies (Schedule Of Depreciable Plant By Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Depreciable plant	$ 12,547,784	$ 11,906,360
Exploration And Production [Member]
Segment Reporting Information [Line Items]
Depreciable plant	6,827,122	6,384,086
Pipeline And Storage [Member]
Segment Reporting Information [Line Items]
Depreciable plant	2,467,891	2,418,265
Gathering [Member]
Segment Reporting Information [Line Items]
Depreciable plant	932,583	849,204
Utility [Member]
Segment Reporting Information [Line Items]
Depreciable plant	2,306,603	2,234,433
All Other And Corporate [Member]
Segment Reporting Information [Line Items]
Depreciable plant	$ 13,585	$ 20,372