DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Ineffectiveness related to derivative instruments	$ 0	$ 0
Natural Gas Revenues
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Amount of Gain (Loss) Recognized in Income on Derivatives Not Designated	0	42
Derivatives Designated as Hedging Instruments
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	15,370	55,670
Derivatives Designated as Hedging Instruments \| Natural Gas Revenues
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	13,328	56,996
Derivatives Designated as Hedging Instruments \| Crude Oil and Condensate Revenues
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	2,042	(1,326)
Derivatives Designated as Hedging Instruments \| Commodity contracts
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Amount of Gain (Loss) Recognized In OCI on Derivatives (Effective Portion)	(60,946)	70,728
Derivatives Not Designated as Hedging Instruments \| Commodity contracts \| Natural Gas Revenues
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Amount of Gain (Loss) Recognized in Income on Derivatives Not Designated		$ 42

Before tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

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+ Details

- Definition

Before tax amount of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

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+ Details