STOCK PLANS AND SHARE-BASED COMPENSATION (Stock-Based Compensation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 4,191	$ 3,847	$ 12,155	$ 10,520
Unrecognized Compensation Expense for Unvested Awards	24,236		24,236
Cost of revenues [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	296	271	824	772
Research and development [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,485	1,467	4,231	4,154
Sales and marketing [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	964	940	2,588	2,433
General and administrative [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,446	1,169	4,512	3,161
Stock Options [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	600	1,100	2,300	3,000
Unrecognized Compensation Expense for Unvested Awards	2,204		2,204
Weighted Average Remaining Recognition Period (in years)			1 year 8 months 5 days
Performance Based Awards [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	800	400	2,200	1,600
Unrecognized Compensation Expense for Unvested Awards	928		928
Weighted Average Remaining Recognition Period (in 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	2,500	2,000	6,800	5,100
Unrecognized Compensation Expense for Unvested Awards	20,665		20,665
Weighted Average Remaining Recognition Period (in years)			2 years 7 months 28 days
Employee Stock [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	300	300	900	800
Unrecognized Compensation Expense for Unvested Awards	$ 439		$ 439
Weighted Average Remaining Recognition Period (in years)			6 months