INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Long-Lived Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 107,889	$ 103,651
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	105,431	100,990
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 2,458	$ 2,661