INVESTMENTS IN EQUITY INVESTEES (Details) (USD $)	12 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Schedule of Equity Method Investments [Line Items]
Investments in equity investees	$ 159,063,000	$ 158,944,000
Steckman Ridge [Member] \| Equity Method Investee [Member]
Equity Method Investment, Summarized Financial Information [Abstract]
Outstanding principal balance	70,400,000
Steckman Ridge [Member]
Schedule of Equity Method Investments [Line Items]
Investments in equity investees	135,130,000	134,359,000
Equity Method Investment, Summarized Financial Information [Abstract]
Operating revenues	29,172,000	25,910,000	8,725,000
Operating income	21,767,000	18,568,000	5,480,000
Net income	20,053,000	16,772,000	4,262,000
Current assets	10,236,000	6,553,000	10,937,000
Noncurrent assets	247,943,000	250,720,000	250,186,000
Current liabilities	1,046,000	1,993,000	11,715,000
Noncurrent liabilities	140,811,000	140,811,000	135,011,000
Iroquois [Member]
Schedule of Equity Method Investments [Line Items]
Investments in equity investees	23,933,000	24,585,000
Equity Method Investment, Summarized Financial Information [Abstract]
Operating revenues	202,581,000	204,059,000	195,185,000
Operating income	111,540,000	116,760,000	111,703,000
Net income	88,208,000	83,359,000	84,376,000
Current assets	101,575,000	102,585,000	92,000,000
Noncurrent assets	716,686,000	746,286,000	769,327,000
Current liabilities	31,158,000	33,664,000	240,512,000
Noncurrent liabilities	$ 378,099,000	$ 394,627,000	$ 264,578,000

Aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due after one year (or one business cycle).

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- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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The amount of current assets reported by an equity method investment of the entity.

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-Name Statement of Financial Accounting Standard (FAS)

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The amount of current liabilities reported by an equity method investment of the entity.

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- Definition

The amount of gross profit (loss) reported by an equity method investment of the entity.

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The amount of net income (loss) reported by an equity method investment of the entity.

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The amount of noncurrent assets reported by an equity method investment of the entity.

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The amount of noncurrent liabilities reported by an equity method investment of the entity.

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- Definition

The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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