Summary Of Significant Accounting Policies (Components Of Other Current Assets) (Details) (USD $) In Thousands	Jun. 30, 2011	Sep. 30, 2010
Prepayments	$ 12,645	$ 13,884
Prepaid Property and Other Taxes	10,653	12,413
Fair Values of Firm Commitments	4,072	15,331
Other Current Assets	44,786	115,969
Federal [Member]
Income Taxes Receivable	9,514	56,334
State [Member]
Income Taxes Receivable	$ 7,902	$ 18,007

Firm Commitments to purchase or sell natural gas that are hedged and accounted for as fair value hedges in accordance with SFAS 133.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 109
-Section Appendix E
-Paragraph 289

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 8
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 5
-Subparagraph c
-Article 7

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- Definition

Aggregate carrying amount, as of the balance sheet date, of current assets not separately presented elsewhere in the balance sheet. Current assets are expected to be realized or consumed within one year (or the normal operating cycle, if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 8
-Article 5

+ Details

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- Definition

Carrying amount as of the balance sheet date of expenditures made, not otherwise specified in the taxonomy, in advance of the timing of recognition of expenses which are expected to be charged against earnings within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 4

+ Details

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 4

+ Details

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