PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
PROPERTY AND EQUIPMENT
Total property and equipment	$ 363,910		$ 363,910		$ 355,481
Accumulated depreciation and amortization	(139,353)		(139,353)		(127,797)
Property and equipment, net	224,557		224,557		227,684
Depreciation and amortization expense	7,656	$ 4,573	15,135	$ 8,412
Cell development costs
PROPERTY AND EQUIPMENT
Total property and equipment	120,766		120,766		120,878
Land and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	33,399		33,399		33,002
Buildings and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	73,355		73,355		74,518
Railcars
PROPERTY AND EQUIPMENT
Total property and equipment	17,375		17,375		17,375
Vehicles and other equipment
PROPERTY AND EQUIPMENT
Total property and equipment	104,187		104,187		98,877
Construction in progress
PROPERTY AND EQUIPMENT
Total property and equipment	$ 14,828		$ 14,828		$ 10,831