PROPERTY, PLANT AND EQUIPMENT - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 5,867,000	$ 5,107,000	$ 2,297,000
Amortization expense	$ 1,663,000	$ 1,663,000	$ 346,000