SEGMENT AND GEOGRAPHIC INFORMATION (Total Revenue by Major Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total revenue, net	$ 368,602	$ 278,834	$ 282,164	$ 258,636	$ 255,664	$ 250,332	$ 249,309	$ 236,770	$ 1,188,236	$ 992,075	$ 882,734
Total long-lived assets	285,329				234,103				285,329	234,103
United States (Includes long-lived assets in Puerto Rico)
Segment Reporting Information [Line Items]
Total revenue, net									894,260	765,608	680,824
Total long-lived assets	247,154				213,898				247,154	213,898
Europe
Segment Reporting Information [Line Items]
Total revenue, net									150,147	120,588	103,057
Total long-lived assets	30,942				18,970				30,942	18,970
Rest of the World
Segment Reporting Information [Line Items]
Total revenue, net									143,829	105,879	$ 98,853
Total long-lived assets	$ 7,233				$ 1,235				$ 7,233	$ 1,235