Summary Of Significant Accounting Policies (Schedule Of Depreciable Plant By Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Depreciable plant	$ 10,788,616	$ 10,076,671
Utility [Member]
Segment Reporting Information [Line Items]
Depreciable plant	2,159,841	2,104,437
Pipeline And Storage [Member]
Segment Reporting Information [Line Items]
Depreciable plant	2,191,166	2,110,714
Exploration And Production [Member]
Segment Reporting Information [Line Items]
Depreciable plant	5,747,731	5,222,037
Gathering [Member]
Segment Reporting Information [Line Items]
Depreciable plant	577,021	527,188
All Other And Corporate [Member]
Segment Reporting Information [Line Items]
Depreciable plant	$ 112,857	$ 112,295