Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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STOCK PLANS AND SHARE-BASED COMPENSATION (Stock-Based Compensation) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 3,361	$ 2,580	$ 11,502	$ 10,670
Unrecognized Compensation Expense for Unvested Awards	25,574		25,574
Stock Options [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	100	200	500	1,000
Unrecognized Compensation Expense for Unvested Awards	296		$ 296
Weighted Average Remaining Recognition Period (in years)			6 months 25 days
Performance Based Awards (PSUs) [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Unrecognized Compensation Expense for Unvested Awards	189		$ 189
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	606		$ 606
Weighted Average Remaining Recognition Period (in years)			1 year 9 months 22 days
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	3,200	2,800	$ 9,500	8,400
Unrecognized Compensation Expense for Unvested Awards	24,049		$ 24,049
Weighted Average Remaining Recognition Period (in years)			2 years 5 months 15 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	400	$ 900	900
Unrecognized Compensation Expense for Unvested Awards	434		$ 434
Weighted Average Remaining Recognition Period (in years)			4 months 2 days
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	131	$ 725	648
Research and development [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	1,277	971	3,974	3,522
Sales and marketing [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	877	779	2,767	2,578
General and administrative [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 988	$ 699	$ 4,036	$ 3,922