INVENTORIES (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
INVENTORIES
Coal	$ 56,366	$ 83,682
Supplies (net of reserve for obsolescence of $3,729 and $3,841, respectively)	33,538	37,399
Total inventory	89,904	121,081
Reserve for obsolescence	4,005	$ 3,841
Adjustment to reduce carrying value of coal inventories to market	$ 16,100