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Share-based Payments Share-Based Payments Fair Value Assumptions (Details) (USD $)
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12 Months Ended | ||
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Dec. 31, 2011
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Dec. 31, 2010
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Dec. 31, 2009
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| Share-based Compensation Arrangement by Share-based Payment Award | |||
| Stock option awards, fair value assumptions, expected dividends | 0.00% | 0.00% | 0.00% |
| Stock option awards, fair value assumptions, expected volatility rate | 49.88% | 54.74% | 50.01% |
| Stock option awards, fair value assumptions, risk-free interest rate | 2.06% | 2.24% | 1.99% |
| Stock options awards, fair value assumptions, expected term | 5 | 5 | 5 |
| Stock option awards, grants in period, weighted average grant date fair value | $ 6.49 | $ 3.23 | $ 6.43 |
| Stock option awards, grants in period, weighted average exercise price | $ 14.37 | $ 6.62 | $ 14.23 |
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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
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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- 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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- Details
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- Definition
The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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