Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 22,138	$ 5,346
Reserve for Gas Replacement	(15,944)	(34,252)
Other	24,844	30,703
Other Accruals and Current Liabilities	72,759	96,557
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	19,287	53,652
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	6,490	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	$ 0	$ 1,170