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.

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-Publisher FASB

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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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.

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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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No definition available.

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

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stock-Based Compensation
Stock-based compensation expense included in operating expenses	$ 2,102	$ 886	$ 3,743	$ 2,234
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)			83.50%	67.40%
Expected volatility range, maximum (as a percent)			106.20%	139.10%
Risk-free interest rate range, minimum (as a percent)			0.09%	0.12%
Risk-free interest rate range, maximum (as a percent)			0.15%	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
Service-based restricted stock awards
Stock-Based Compensation
Vesting period of awards			4 years
Performance-based restricted stock awards
Stock-Based Compensation
Vesting period of awards			3 years
Stock-based compensation expense included in operating expenses	$ 0	$ 0	$ 0	$ 0
Assumptions used to estimate fair value of awards
Non-vested restricted stock at the end of the period (in shares)	0		0
Stock Options
Stock-Based Compensation
Vesting period of awards			4 years
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)			0.00%	0.00%
Expected volatility range, minimum (as a percent)			89.80%	74.20%
Expected volatility range, maximum (as a percent)			92.20%	74.50%
Risk-free interest rate range, minimum (as a percent)			1.64%	0.80%
Risk-free interest rate range, maximum (as a percent)			1.92%	1.26%
Expected term			5 years 6 months	6 years