PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, plant and equipment
Subtotal	$ 438,559	$ 429,567
Less: accumulated depreciation	(182,233)	(174,748)
Total property, plant and equipment, net	256,326	254,819
Land
Property, plant and equipment
Subtotal	5,913	5,913
Buildings and improvements
Property, plant and equipment
Subtotal	138,789	136,797
Furniture, fixtures and equipment
Property, plant and equipment
Subtotal	222,958	218,718
Leasehold improvements
Property, plant and equipment
Subtotal	16,632	16,597
Construction in progress
Property, plant and equipment
Subtotal	$ 54,267	$ 51,542