DERIVATIVE INSTRUMENTS 2 (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	$ 41,651	$ 45,596
Fair value Derivative Liabilities	39,735	60,151
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	41,651	45,596
Fair value Derivative Liabilities	35,911	56,789
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	0	0
Fair value Derivative Liabilities	3,824	3,362
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Derivatives-Energy Related-Current [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	31,254	37,461
Fair value Derivative Liabilities	19,340	38,738
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Derivatives-Energy Related-NonCurrent [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	10,397	8,135
Fair value Derivative Liabilities	5,574	7,367
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	10,997	10,684
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	$ 3,824	$ 3,362