Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 29,579	$ 14,725
Reserve for Gas Replacement	(9,027)	(34,332)
Other	33,174	32,909
Other Accruals and Current Liabilities	106,287	74,430
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	13,964	26,796
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	20,215	0
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Payable	$ 9,355	$ 0