SEGMENT AND GEOGRAPHICAL INFORMATION - Revenue by Geography (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 461,554	$ 379,269
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	444,899	367,164
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 16,655	$ 12,105