Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Summary Of Significant Accounting Policies [Line Items]
Prepayments	$ 3,568	$ 8,316
Prepaid Property and Other Taxes	20,858	14,455
Fair Values of Firm Commitments	0	1,291
Regulatory Assets	25,671	29,726
Other Current Assets	51,731	56,121
Federal [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable	749	268
State [Member]
Summary Of Significant Accounting Policies [Line Items]
Income Taxes Receivable	$ 885	$ 2,065

Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

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Carrying amount as of the balance sheet date of payments made in advance for income and other taxes, which will be charged against earnings within one year or the normal operating cycle, if longer.

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

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