Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liability	$ 34,262	$ 62,124
Other Accruals and Current Liabilities	74,430	96,557
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	26,796	53,652
Regulatory Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liability	14,725	5,346
Other Accruals [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	32,909	30,703
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	0	5,686
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	$ 0	$ 1,170