STOCK-BASED COMPENSATION Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	$ 4,416	$ 4,391
Stock Options
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	100	200
Performance Based Awards and Long Term Performance based Units
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	700	600
Restricted Stock Units (RSUs)
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	3,300	3,300
Employee Stock Purchase Plan
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	300	300
Cost of revenues
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	90	249
Research and development
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	1,469	1,391
Sales and marketing
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	1,027	1,012
General and administrative
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	$ 1,830	$ 1,739