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Summary of Significant Accounting Policies (Details 3)
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3 Months Ended | |
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Mar. 31, 2012
Y
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Mar. 31, 2011
Y
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| Stock-Based Compensation | ||
| Time period of historical volatility of stock used to estimate expected volatility (in years) | 5.82 | |
| Weighted-average assumptions used in the Black-Scholes option-pricing model | ||
| Risk-free interest rate (as a percent) | 1.04% | 2.27% |
| Expected volatility (as a percent) | 47.60% | 48.02% |
| Weighted-average expected life (in years) | 5.82 | 5.73 |
| Forfeiture rate (as a percent) | 5.00% | 5.00% |
| X | ||||||||||
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- Definition
Represents the time period of historical volatility of stock used to estimate expected volatility, in years. No definition available.
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- Definition
The percentage estimated forfeiture rate based on historical experience at the date of the grant. No definition available.
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- Details
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- Details
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- Definition
The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior. 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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- 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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