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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Assumptions used to estimate fair value of awards
Stock-based compensation expense included in operating expenses	$ 1,222	$ 1,263	$ 3,456	$ 4,016
Stock options
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)			0.00%	0.00%
Expected volatility range, minimum (as a percent)			74.20%	63.10%
Expected volatility range, maximum (as a percent)			75.90%	72.60%
Risk-free interest rate range, minimum (as a percent)			0.80%	0.81%
Risk-free interest rate range, maximum (as a percent)			1.81%	1.25%
Expected term			6 years	6 years
Vesting period of awards			4 years
Restricted stock awards
Assumptions used to estimate fair value of awards
Types of vesting schedules (in count)			3
Service-based restricted stock awards
Assumptions used to estimate fair value of awards
Vesting period of awards			4 years
Performance-based restricted stock awards
Assumptions used to estimate fair value of awards
Vesting period of awards			3 years
Stock-based compensation expense included in operating expenses	$ 0	$ 0	$ 0	$ 0
Market-based restricted stock awards
Assumptions used to estimate fair value of awards
Vesting period of awards			3 years
Employee Stock Purchase Plan
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)			0.00%	0.00%
Expected volatility range, minimum (as a percent)			50.60%	45.80%
Expected volatility range, maximum (as a percent)			139.10%	77.40%
Risk-free interest rate range, minimum (as a percent)			0.09%	0.06%
Risk-free interest rate range, maximum (as a percent)			0.21%	0.21%
Employee Stock Purchase Plan | Minimum
Assumptions used to estimate fair value of awards
Expected term			6 months	6 months
Employee Stock Purchase Plan | Maximum
Assumptions used to estimate fair value of awards
Expected term			12 months	12 months

X

- Definition

Represents the types of vesting schedules.

+ 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 50

-Paragraph 1

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-Name Staff Accounting Bulletin (SAB)

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

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.

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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

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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.

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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.

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

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