STOCK PLANS AND SHARE-BASED COMPENSATION (Stock-Based Compensation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 4,175	$ 4,328	$ 8,090	$ 7,964
Unrecognized Compensation Expense for Unvested Awards	29,759		29,759
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	700	1,000	1,700
Unrecognized Compensation Expense for Unvested Awards	1,215		1,215
Weighted Average Remaining Recognition Period (in years)			1 year 6 months 3 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	700	900	1,300	1,300
Unrecognized Compensation Expense for Unvested Awards	1,948		1,948
Weighted Average Remaining Recognition Period (in years)			6 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	1,961		1,961
Weighted Average Remaining Recognition Period (in years)			2 years 6 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	2,700	2,400	5,200	4,400
Unrecognized Compensation Expense for Unvested Awards	24,534		24,534
Weighted Average Remaining Recognition Period (in years)			2 years 9 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	300	300	600	600
Unrecognized Compensation Expense for Unvested Awards	101		101
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	298	264	517	528
Research and development [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,339	1,640	2,551	2,746
Sales and marketing [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	864	795	1,799	1,624
General and administrative [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 1,674	$ 1,629	$ 3,223	$ 3,066