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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

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- Definition Represents the types of vesting schedules. + References No definition available. + Details
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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 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: 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) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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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. + 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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. + 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 + Details
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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 + Details
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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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