DERIVATIVE INSTRUMENTS 2 (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	$ 36,539	$ 45,596
Fair value Derivative Liabilities	42,693	60,151
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	36,539	45,596
Fair value Derivative Liabilities	42,693	56,789
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value Derivative Assets	0	0
Fair value Derivative Liabilities	0	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	24,242	37,461
Fair value Derivative Liabilities	23,828	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	12,297	8,135
Fair value Derivative Liabilities	5,403	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	13,462	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	$ 0	$ 3,362