PROPERTY AND EQUIPMENT (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
PROPERTY AND EQUIPMENT
Total property and equipment	$ 202,160		$ 202,160		$ 182,087
Accumulated depreciation and amortization	(91,402)		(91,402)		(82,112)
Property and equipment, net	110,758		110,758		99,975
Depreciation expense	3,400	3,600	10,222	9,911
Cell development costs
PROPERTY AND EQUIPMENT
Total property and equipment	65,042		65,042		61,749
Land and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	14,832		14,832		13,929
Building and improvements
PROPERTY AND EQUIPMENT
Total property and equipment	55,355		55,355		51,409
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	38,330		38,330		33,594
Construction in progress
PROPERTY AND EQUIPMENT
Total property and equipment	$ 11,226		$ 11,226		$ 4,031