STOCK PLANS AND SHARE-BASED COMPENSATION (Stock-Based Compensation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 2,580	$ 4,191	$ 10,670	$ 12,155
Unrecognized Compensation Expense for Unvested Awards	25,158		25,158
Employee Stock Option [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	200	600	1,000	2,300
Unrecognized Compensation Expense for Unvested Awards	999		999
Weighted Average Remaining Recognition Period (in years)			1 year 3 months 18 days
Performance Based Awards (PSUs) [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	(800)	800	400	2,200
Unrecognized Compensation Expense for Unvested Awards	164		164
Weighted Average Remaining Recognition Period (in years)			3 months
Long-Term Performance-based Awards (PRSUs) [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Unrecognized Compensation Expense for Unvested Awards	1,076		1,076
Weighted Average Remaining Recognition Period (in years)			2 years 3 months
Restricted Stock Units (RSUs) [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	2,800	2,500	8,400	6,800
Unrecognized Compensation Expense for Unvested Awards	22,349		22,349
Weighted Average Remaining Recognition Period (in years)			2 years 6 months 3 days
Employee Stock [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	400	300	900	900
Unrecognized Compensation Expense for Unvested Awards	570		570
Weighted Average Remaining Recognition Period (in years)			6 months
Cost of revenues [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	131	296	648	824
Research and development [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	971	1,485	3,522	4,231
Sales and marketing [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	779	964	2,578	2,588
General and administrative [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 699	$ 1,446	$ 3,922	$ 4,512