Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Sep. 30, 2015
Summary Of Significant Accounting Policies [Line Items]
Prepayments		$ 10,919	$ 10,743
Prepaid Property and Other Taxes		13,138	13,709
Fair Values of Firm Commitments		3,962	15,775
Regulatory Assets	[1]	15,616	20,438
Other Current Assets		59,354	60,665
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable		11,758	0
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable		$ 3,961	$ 0

[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.