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Share-Based Compensation - Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted (Detail)
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12 Months Ended | ||
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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| Weighted-Average Assumptions | |||
| Dividend yield | |||
| Expected Volatility | 65.23% | 103.76% | |
| Expected Term | 3 years | 3 years 2 months 12 days | |
| Risk-Free Interest Rate | 0.32% | 1.04% | |
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- 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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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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- 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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- 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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