INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Income tax benefit	$ (651)	$ (1,049)	$ (749)
Acquisitions in Canada | Foreign Tax Authority | Canada Revenue Agency
Business Acquisition [Line Items]
Income tax benefit	1,300	700	700
Valuation allowance	$ 1,200	$ 700	$ 700