INFORMATION ABOUT REVENUE AND GEOGRAPHIC AREAS (Long-Lived Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 114,800	$ 103,651	$ 92,440
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	112,984	100,990	89,362
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 1,816	$ 2,661	$ 3,078