Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Sep. 30, 2019
Summary Of Significant Accounting Policies [Line Items]
Prepayments		$ 12,851	$ 12,728
Prepaid Property and Other Taxes		14,269	14,361
Fair Values of Firm Commitments		0	7,538
Regulatory Assets	[1]	16,609	11,460
Other Current Assets		47,557	97,054
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable		0	42,388
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable		$ 3,828	$ 8,579

[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.