STOCK-BASED COMPENSATION (Details)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ESPP
Assumptions used to calculate the fair value of awards granted
Risk-free interest rate, minimum (as a percent)	0.06%	0.08%	0.12%
Risk-free interest rate, maximum (as a percent)	0.08%	0.10%	0.16%
Dividend yield	0.00%	0.00%	0.00%
Expected option term	6 months	6 months
Expected stock price volatility, minimum (as a percent)	44.80%	28.80%	35.60%
Expected stock price volatility, maximum (as a percent)	61.40%	35.00%	44.30%
ESPP \| Minimum
Assumptions used to calculate the fair value of awards granted
Expected option term			6 months
ESPP \| Maximum
Assumptions used to calculate the fair value of awards granted
Expected option term			6 months
Stock options
Assumptions used to calculate the fair value of awards granted
Risk-free interest rate, minimum (as a percent)	1.26%	0.67%	0.51%
Risk-free interest rate, maximum (as a percent)	1.51%	1.38%	0.78%
Dividend yield	0.00%	0.00%	0.00%
Expected stock price volatility, minimum (as a percent)	42.60%	49.20%	64.10%
Expected stock price volatility, maximum (as a percent)	49.00%	63.50%	67.50%
Stock options \| Minimum
Assumptions used to calculate the fair value of awards granted
Expected option term	4 years 3 months 29 days	4 years 5 months 23 days	4 years 6 months
Stock options \| Maximum
Assumptions used to calculate the fair value of awards granted
Expected option term	4 years 4 months 28 days	4 years 6 months 4 days	4 years 6 months 15 days

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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.D.2)

-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section D

-Subsection 2

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- Definition

The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

+ Details

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- Definition

The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

No definition available.

+ Details

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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