DERIVATIVE FINANCIAL INSTRUMENTS (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Amount of gains (losses) recognized in income from derivative instruments not designated as hedging instruments
Total	$ (1,205)	$ (3,383)	$ 491	$ (3,772)
Commodity derivatives | Not designated as hedging instruments
Amount of gains (losses) recognized in income from derivative instruments not designated as hedging instruments
Realized cash settlements on hedges	(181)	(688)	(857)	(1,542)
Unrealized non-cash gain (loss) on hedges	(1,024)	(2,695)	1,348	(2,230)
Total	$ (1,205)	$ (3,383)	$ 491	$ (3,772)