PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
PROPERTY AND EQUIPMENT
Total property and equipment	$ 381,486		$ 381,486		$ 354,308
Accumulated depreciation and amortization	(162,184)		(162,184)		(143,974)
Property and equipment, net	219,302		219,302		210,334
Depreciation and amortization expense	6,454	$ 6,591	18,561	$ 21,726
Cell development costs
PROPERTY AND EQUIPMENT
Total property and equipment	123,036		123,036		121,473
Land and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	33,503		33,503		31,606
Buildings and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	76,680		76,680		70,990
Railcars
PROPERTY AND EQUIPMENT
Total property and equipment	17,299		17,299		17,375
Vehicles and other equipment
PROPERTY AND EQUIPMENT
Total property and equipment	104,546		104,546		92,797
Construction in progress
PROPERTY AND EQUIPMENT
Total property and equipment	$ 26,422		$ 26,422		$ 20,067