DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Details 2) (USD $)	3 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Asset	$ 87,607,000	$ 50,824,000
Fair Value Liability		192,000
Unrealized gains included in Accumulated Other Comprehensive Income, net of tax	53,100,000	30,700,000
Expected reclassification of income from commodity hedges over the next 12 months	42,300,000
Accumulated Net Gains / (Losses) on Cash Flow Hedges
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Unrealized gains included in Accumulated Other Comprehensive Income, pretax	87,600,000	50,600,000
Derivatives Designated as Hedging Instruments
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Asset	87,607,000	50,824,000
Fair Value Liability		192,000
Derivatives Designated as Hedging Instruments | Commodity contracts | Current Assets
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Asset	69,644,000	50,824,000
Derivatives Designated as Hedging Instruments | Commodity contracts | non-current assets
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Asset	17,963,000
Derivatives Designated as Hedging Instruments | Commodity contracts | Accrued liabilities
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Liability		$ 192,000