SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property, Plant, and Equipment (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 142,892	$ 122,232
Less accumulated depreciation	(65,264)	(62,619)
Property, plant and equipment, net	77,628	59,613
Land and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	11,333	10,027
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	66,826	57,697
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	44,161	34,984
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	10,227	9,243
Software costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 10,345	$ 10,281