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Share-based Compensation (Details) (Stock options, USD $)
|
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
|
Jun. 30, 2012
year
|
Jun. 30, 2011
year
|
Jun. 30, 2012
year
|
Jun. 30, 2011
year
|
|
|
Stock options
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| Fair value assumptions used in computation of grant date fair value of options | ||||
| Number of options granted (in shares) | 195,000 | 22,000 | 235,000 | 34,000 |
| Grant date fair value of options granted per share (in dollars per share) | $ 5.17 | $ 17.76 | $ 5.68 | $ 17.53 |
| Weighted average exercise price of options granted (in dollars per share) | $ 9.19 | $ 31.16 | $ 10.06 | $ 30.61 |
| Volatility (as a percent) | 59.00% | 59.00% | 60.00% | 59.00% |
| Risk free interest rate (as a percent) | 1.40% | 2.40% | 1.40% | 2.50% |
| Expected term (in years) | 6.3 | 6.3 | 6.3 | 6.3 |