STOCK PLANS AND SHARE-BASED COMPENSATION (Stock-Based Compensation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 3,636	$ 3,031
Unrecognized Compensation Expense for Unvested Awards	24,112
Cost of revenues [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	264	245
Research and development [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,106	1,120
Sales and marketing [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	829	747
General and administrative [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,437	919
Stock Options [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,000	900
Unrecognized Compensation Expense for Unvested Awards	3,042
Weighted Average Remaining Recognition Period (in years)	1 year 10 months 21 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	400	400
Unrecognized Compensation Expense for Unvested Awards	1,662
Weighted Average Remaining Recognition Period (in years)	9 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	1,900	1,400
Unrecognized Compensation Expense for Unvested Awards	19,029
Weighted Average Remaining Recognition Period (in years)	2 years 8 months 16 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
Unrecognized Compensation Expense for Unvested Awards	$ 379
Weighted Average Remaining Recognition Period (in years)	6 months