Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Sep. 30, 2017
Summary Of Significant Accounting Policies [Line Items]
Prepayments		$ 11,126	$ 10,927
Prepaid Property and Other Taxes		14,088	13,974
Fair Values of Firm Commitments		1,739	1,031
Regulatory Assets	[1]	9,792	15,884
Other Current Assets		68,024	51,505
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable		22,457	0
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable		$ 8,822	$ 9,689

[1] The Company recovers the cost of its regulatory assets but generally does not earn a return on them. There are a few exceptions to this rule. For example, the Company does earn a return on Unrecovered Purchased Gas Costs and, in the New York jurisdiction of its Utility segment, earns a return, within certain parameters, on the excess of cumulative funding to the pension plan over the cumulative amount collected in rates.