SEGMENT AND GEOGRAPHIC INFORMATION - Revenue by Geographic Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	[1]	Dec. 31, 2013	[1]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 359,786	$ 349,019		$ 330,399
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	193,785	172,607		163,366
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	92,546	109,959		109,228
APAC [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	53,833	47,863		41,063
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 19,622	$ 18,590		$ 16,742

[1] The revenue by region for the years ended December 31, 2014 and 2013 have been corrected from amounts previously reported.