Summary Of Significant Accounting Policies (Schedule Of Other Accruals And Current Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Sep. 30, 2016
Summary Of Significant Accounting Policies [Line Items]
Regulatory Liabilities	$ 17,984	$ 14,725
Reserve for Gas Replacement	(23,431)	(34,332)
Fair Values of Firm Commitments	3,832	0
Other	35,951	32,909
Other Accruals and Current Liabilities	88,519	74,430
Accrued Capital Expenditures [Member]
Summary Of Significant Accounting Policies [Line Items]
Other	29,052	26,796
Reserve For Gas Replacement [Member]
Summary Of Significant Accounting Policies [Line Items]
Reserve for Gas Replacement	$ 1,700	$ 0