SEGMENT AND GEOGRAPHIC INFORMATION (Total Revenue by Major Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total revenue, net	$ 255,664	$ 250,332	$ 249,309	$ 236,770	$ 241,160	$ 226,367	$ 212,673	$ 202,534	$ 992,075	$ 882,734	$ 796,717
Total long-lived assets	234,103				213,147				234,103	213,147
United States
Segment Reporting Information [Line Items]
Total revenue, net									765,608	680,824	596,303
Total long-lived assets	213,898				192,900				213,898	192,900
Europe
Segment Reporting Information [Line Items]
Total revenue, net									120,588	103,057	99,207
Total long-lived assets	18,970				19,169				18,970	19,169
Rest of the World
Segment Reporting Information [Line Items]
Total revenue, net									105,879	98,853	$ 101,207
Total long-lived assets	$ 1,235				$ 1,078				$ 1,235	$ 1,078