SEGMENT AND GEOGRAPHIC INFORMATION - Total Revenue by Major Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 250,332	$ 226,367	$ 736,411	$ 641,574
United States
Segment Reporting Information [Line Items]
Revenues	194,346	178,290	567,103	493,559
Europe
Segment Reporting Information [Line Items]
Revenues	28,553	24,275	89,623	75,046
Rest of World
Segment Reporting Information [Line Items]
Revenues	$ 27,433	$ 23,802	$ 79,685	$ 72,969