PROPERTY AND EQUIPMENT - Property and Equipment by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 24,780	$ 11,741
United States
Property, Plant and Equipment [Line Items]
Property and equipment, net	17,576	7,939
Canada
Property, Plant and Equipment [Line Items]
Property and equipment, net	1,740	246
Asia/Pacific
Property, Plant and Equipment [Line Items]
Property and equipment, net	3,853	2,963
Europe
Property, Plant and Equipment [Line Items]
Property and equipment, net	1,400	593
Other
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 211	$ 0