Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 4,695	$ 5,346
Reserve for Gas Replacement	(28,811)	(34,252)
Other	28,046	30,703
Other Accruals and Current Liabilities	95,830	96,557
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	61,362	53,652
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	976	0
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	$ 751	$ 1,170