SEGMENT AND GEOGRAPHIC INFORMATION (Total Revenue by Major Geographic Area) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Total revenue, net	$ 252,176	$ 229,719	$ 231,351	$ 215,059	$ 220,769	$ 213,246	$ 205,547	$ 196,652	$ 928,305	$ 836,214	$ 830,871
Total long-lived assets	220,354				208,648				220,354	208,648
United States
Segment Reporting Information [Line Items]
Total revenue, net									714,040	642,694	642,830
Total long-lived assets	197,897				187,608				197,897	187,608
Europe
Segment Reporting Information [Line Items]
Total revenue, net									105,697	93,977	90,920
Total long-lived assets	21,218				20,010				21,218	20,010
Rest of the World
Segment Reporting Information [Line Items]
Total revenue, net									108,568	99,543	97,121
Total long-lived assets	$ 1,239				$ 1,030				$ 1,239	$ 1,030