DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Effect of derivative instruments on the Condensed Consolidated Statement of Operations
Ineffectiveness related to derivative instruments	$ 0	$ 0	$ 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	(342)	0	(300)
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)	1,822	72,842	17,192	128,512
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)	(272)	69,732	13,056	126,728
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)	2,094	3,110	4,136	1,784
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)	$ 115,113	$ 18,376	$ 54,167	$ 89,104