DERIVATIVE INSTRUMENTS (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commodity derivatives:
Realized gains	$ (14,252)	$ (100,420)	$ (37,535)
Unrealized losses (gains)	17,863	31,630	(37,542)
Interest rate derivatives:
Realized gains	(12,885)	(11,352)	(11,442)
Unrealized losses (gains)	13,060	7,496	(1,545)
Realized and unrealized losses (gains) on derivative instruments, net	$ 3,786	$ (72,646)	$ (88,064)