DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Details 2) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Asset	$ 65,539,000	$ 50,824,000
Fair Value Liability		192,000
Unrealized gains included in Accumulated Other Comprehensive Income, net of tax	39,800,000	30,700,000
Expected reclassification of income from commodity hedges over the next 12 months	34,500,000
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	65,500,000	50,600,000
Derivatives Designated as Hedging Instruments
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Asset	65,539,000	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	56,831,000	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	8,708,000
Derivatives Designated as Hedging Instruments | Commodity contracts | Accrued liabilities
Effect of derivative instruments on the Condensed Consolidated Balance Sheet
Fair Value Liability		$ 192,000