Summary Of Significant Accounting Policies (Schedule Of Depreciable Plant By Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Depreciable plant	$ 8,575,493	$ 7,789,756
Utility [Member]
Segment Reporting Information [Line Items]
Depreciable plant	1,888,489	1,833,104
Pipeline And Storage [Member]
Segment Reporting Information [Line Items]
Depreciable plant	1,710,947	1,609,593
Exploration And Production [Member]
Segment Reporting Information [Line Items]
Depreciable plant	4,556,096	3,995,200
Energy Marketing [Member]
Segment Reporting Information [Line Items]
Depreciable plant	3,494	3,366
Gathering [Member]
Segment Reporting Information [Line Items]
Depreciable plant	307,274	239,507
All Other And Corporate [Member]
Segment Reporting Information [Line Items]
Depreciable plant	$ 109,193	$ 108,986