DERIVATIVE FINANCIAL INSTRUMENTS (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Amount of gains (losses) recognized in income from derivative instruments not designated as hedging instruments
Total	$ 10,644	$ 3,699	$ 11,304	$ 1,038
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	2,644	11	7,778	(3,267)
Mark-to-market gain on hedges	8,000	3,688	3,526	4,305
Total	$ 10,644	$ 3,699	$ 11,304	$ 1,038