EQUITY INVESTMENTS - White Oak (Details) - ARLP - White Oak - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Jul. 31, 2015	Dec. 31, 2014
Equity method investments results
Total revenues	$ 108,256	$ 42,748
Gross loss	(2,919)	(1,134)
Loss from operations	(38,148)	(21,018)
Net loss	$ (69,075)	$ (46,324)