SEGMENT AND GEOGRAPHICAL INFORMATION - Long-lived Assets by Geography (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 167,511	$ 164,793
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	164,906	162,118
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 2,605	$ 2,675