STOCK PLANS (Details 2) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-Based Compensation
Stock-based compensation expense	$ 31,601	$ 31,248	$ 33,368
Compensation expense from stock options, employees	24,056	24,505	27,262
Compensation expense from stock options, non-employee awards	167	841	2,367
Restricted Stock or Unit Expense	6,698	5,117	2,887
Compensation expense from employee stock purchase plan	680	785	852
Stock-based compensation	31,601	31,248	33,368
Cost of revenues
Share-Based Compensation
Stock-based compensation expense	5,467	6,438	6,012
Research and development
Share-Based Compensation
Stock-based compensation expense	3,341	3,297	5,134
Selling, general and administrative
Share-Based Compensation
Stock-based compensation expense	$ 22,793	$ 21,513	$ 22,222

Compensation expense from employee stock purchase plan

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- Definition

Compensation expense from stock options (employee and board of director awards)

+ References

No definition available.

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- Definition

Compensation expense from stock options, non-employee awards

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
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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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No definition available.

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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

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