DERIVATIVE INSTRUMENTS 2 (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	$ 36,891	$ 51,069
Fair value Derivative Liabilities	53,671	58,342
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Derivatives-Energy Related-Current [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	29,572	39,513
Fair value Derivative Liabilities	32,570	42,297
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Derivatives-Energy Related-NonCurrent [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	7,319	11,556
Fair value Derivative Liabilities	7,318	8,641
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Derivatives-Other [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	0	0
Fair value Derivative Liabilities	10,513	5,539
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Derivatives-Other [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	0	0
Fair value Derivative Liabilities	3,270	1,865
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	36,891	51,069
Fair value Derivative Liabilities	50,401	56,477
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	0	0
Fair value Derivative Liabilities	$ 3,270	$ 1,865