INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Long-Lived Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 110,899	$ 103,651
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	108,900	100,990
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 1,999	$ 2,661