FAIR VALUE - HIERARCHY (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 67,198		$ 50,349
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	11,482	[1]	11,009	[1]
Other	1,096	[2]	30	[2]
Total assets at fair value	79,776		61,388
Total liabilities at fair value	40,327		45,573
Fair Value, Measurements, Recurring [Member] | Physical Forward Commodity Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	8,616		20,248
Liabilities	10,135		9,746
Fair Value, Measurements, Recurring [Member] | Financial Derivative Contracts - Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	58,531		29,915
Liabilities	30,152		35,715
Fair Value, Measurements, Recurring [Member] | Financial Derivative Contracts - Foreign Exchange [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	51		186
Liabilities	40		112
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets, (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	11,482	[1]	11,009	[1]
Other	1,096	[2]	30	[2]
Total assets at fair value	71,109		25,309
Total liabilities at fair value	30,115		16,922
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets, (Level 1) [Member] | Physical Forward Commodity Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0		0
Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets, (Level 1) [Member] | Financial Derivative Contracts - Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	58,531		14,270
Liabilities	30,115		16,922
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets, (Level 1) [Member] | Financial Derivative Contracts - Foreign Exchange [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0		0
Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	0	[1]	0	[1]
Other	0	[2]	0	[2]
Total assets at fair value	8,667		36,079
Total liabilities at fair value	10,212		28,651
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Physical Forward Commodity Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	8,616		20,248
Liabilities	10,135		9,746
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Financial Derivative Contracts - Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0		15,645
Liabilities	37		18,793
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Financial Derivative Contracts - Foreign Exchange [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	51		186
Liabilities	40		112
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale equity securities - energy industry	0	[1]	0	[1]
Other	0	[2]	0	[2]
Total assets at fair value	0		0
Total liabilities at fair value	0		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Physical Forward Commodity Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0		0
Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Financial Derivative Contracts - Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0		0
Liabilities	0		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Financial Derivative Contracts - Foreign Exchange [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0		0
Liabilities	$ 0		$ 0

[1] Included in Other noncurrent assets on the Unaudited Condensed Consolidated Balance Sheets

[2] Includes various money market funds.