SEGMENT AND GEOGRAPHIC INFORMATION - Total Revenue by Major Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total Revenues	$ 365,854	$ 278,834	$ 1,089,126	$ 819,634
United States
Segment Reporting Information [Line Items]
Total Revenues	260,870	213,685	769,509	634,047
Europe
Segment Reporting Information [Line Items]
Total Revenues	47,472	32,609	150,650	93,924
Asia Pacific
Segment Reporting Information [Line Items]
Total Revenues	37,022	16,887	108,304	48,540
Rest of World
Segment Reporting Information [Line Items]
Total Revenues	$ 20,490	$ 15,653	$ 60,663	$ 43,123