DERIVATIVE INSTRUMENTS (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Commodity derivatives:
Realized losses (gains)	$ 1,106	$ (31,067)	$ (8,543)	$ (52,395)
Unrealized (gains) losses	(32,823)	(2,126)	2,338	(8,572)
Interest rate derivatives:
Realized gains	(9,803)	(2,837)	(12,885)	(5,721)
Unrealized losses	9,910	2,015	13,060	3,149
Realized and unrealized gains on derivative instruments, net	$ (31,610)	$ (34,015)	$ (6,030)	$ (63,539)