PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, plant and equipment
Property, plant and equipment, gross	$ 186,421	$ 184,304
Accumulated depreciation	(124,109)	(122,279)
Property, plant and equipment, net	62,312	62,025
Land, buildings and improvements
Property, plant and equipment
Property, plant and equipment, gross	84,159	82,201
Machinery, equipment and fixtures
Property, plant and equipment
Property, plant and equipment, gross	79,274	79,176
Office furniture, equipment and vehicles
Property, plant and equipment
Property, plant and equipment, gross	22,787	22,689
Construction in progress
Property, plant and equipment
Property, plant and equipment, gross	$ 201	$ 238