STOCK PLANS AND SHARE-BASED COMPENSATION (Stock-Based Compensation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 3,915	$ 3,636
Unrecognized Compensation Expense for Unvested Awards	26,266
Cost of revenues [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	219	264
Research and development [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,212	1,106
Sales and marketing [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	935	829
General and administrative [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,549	1,437
Employee Stock Option [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	500	1,000
Unrecognized Compensation Expense for Unvested Awards	1,497
Weighted Average Remaining Recognition Period (in years)	1 year 5 months 8 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	500	400
Unrecognized Compensation Expense for Unvested Awards	1,706
Weighted Average Remaining Recognition Period (in years)	9 months
Long-Term Performance-based Awards [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Unrecognized Compensation Expense for Unvested Awards	2,156
Weighted Average Remaining Recognition Period (in years)	2 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	2,600	1,900
Unrecognized Compensation Expense for Unvested Awards	20,511
Weighted Average Remaining Recognition Period (in years)	2 years 4 months 17 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	$ 396
Weighted Average Remaining Recognition Period (in years)	6 months