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Stockholders' Equity (Details 1)
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12 Months Ended | ||
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Jan. 31, 2013
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Jan. 31, 2012
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Jan. 31, 2011
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| Expected volatility (range) | 52.00% | ||
| Expected volatility (range), Minimum | 49.00% | 51.00% | |
| Expected volatility (range), Maximum | 52.00% | 53.00% | |
| Weighted average volatility | 52.00% | 52.00% | 53.00% |
| Risk-free interest rate | 0.80% | ||
| Weighted average interest rate | 1.20% | 0.80% | 1.60% |
| Expected dividend yield | 0.00% | 0.00% | 0.00% |
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Maximum [Member]
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| Expected term (in years) | 7 years | 5 years | 5 years |
| Risk-free interest rate | 1.20% | 1.60% | |
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Minimum [Member]
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| Expected term (in years) | 3 years | 4 years | 4 years |
| Risk-free interest rate | 0.70% | 1.50% | |
| X | ||||||||||
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- Definition
The range of expected interest rates used and the weighted-average expected interest rates for an entity using a valuation technique with different interests during the contractual term. No definition available.
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| X | ||||||||||
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The estimated measure of the 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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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. No definition available.
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| X | ||||||||||
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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. No definition available.
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| X | ||||||||||
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- Definition
The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The range of expected volatilities used and the weighted-average expected volatility for an entity using a valuation technique with different volatilities during the contractual term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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