Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liability	$ 34,059	$ 34,262
Other Accruals and Current Liabilities	111,889	74,430
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	37,382	26,796
Regulatory Liabilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liability	34,059	14,725
Other Accruals [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	38,673	32,909
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	$ 1,775	$ 0