SEGMENT REPORTING (Details 5) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue and long-lived assets excluding intangible assets, by geographical area
Revenue	$ 474,470	$ 482,083	$ 373,085
Long-lived assets	85,292	88,319
United States
Revenue and long-lived assets excluding intangible assets, by geographical area
Revenue	410,768	431,615	346,454
Long-lived assets	78,921	84,384
United Kingdom
Revenue and long-lived assets excluding intangible assets, by geographical area
Revenue	49,710	45,962	23,356
Other countries
Revenue and long-lived assets excluding intangible assets, by geographical area
Revenue	13,992	4,506	3,275
Long-lived assets	$ 6,371	$ 3,935