STOCK-BASED COMPENSATION Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	$ 5,789	$ 3,361	$ 15,217	$ 11,502
Stock Options
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense		100	200	500
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	2,100	(200)	4,400	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	3,400	3,200	9,700	9,500
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	900	900
Cost of revenues
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	348	219	731	725
Research and development
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	1,934	1,277	5,343	3,974
Sales and marketing
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	1,303	877	3,229	2,767
General and administrative
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-Based Compensation Expense	$ 2,204	$ 988	$ 5,914	$ 4,036