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Equity Incentive Plans and Stock-Based Compensation (Tables) | 9 Months Ended
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Sep. 30, 2011
Equity Incentive Plans and Stock-Based Compensation |
Shares available for grant under stock-based incentive plans |
|  | Shares Available for Grant |
Shares available as of December 31, 2010 |  | 5,348,162 |
Stock options granted |  | (2,199,761 | )
Stock options forfeited |  | 770,903 |
Stock options expired under former plans |  | (471,913 | )
Nonvested equity stock and stock units granted (1) |  | (440,331 | )
Nonvested equity stock and stock units forfeited (1) |  | 22,401 |
Total available for grant as of September 30, 2011 |  | 3,029,461 |
(1) For purposes of determining the number of shares available for grant under the 2006 Plan against the maximum number of shares authorized, each restricted stock granted reduces the number of shares available for grant by 1.5 shares and each restricted stock forfeited increases shares available for grant by 1.5 shares.
Schedule of stock option activity |
|  | Options Outstanding |  | Weighted |  |  |
|  | Number of Shares |  | Weighted Average Exercise Price Per Share |  | Average Remaining Contractual Term (in years) |  | Aggregate Intrinsic Value |
|  | (Dollars in thousands, except per share amounts) |
Outstanding as of December 31, 2010 |  | 13,969,383 |  | $ | 18.85 |  |  |  |  |
Options granted |  | 2,199,761 |  | 19.27 |  |  |  |  |
Options exercised |  | (757,888 | ) | 8.50 |  |  |  |  |
Options forfeited |  | (770,903 | ) | 13.42 |  |  |  |  |
Outstanding as of September 30, 2011 |  | 14,640,353 |  | 19.74 |  | 5.67 |  | $ | 10,378 |
Vested or expected to vest at September 30, 2011 |  | 14,098,821 |  | 19.77 |  | 5.55 |  | 10,063 |
Options exercisable at September 30, 2011 |  | 10,196,979 |  | 20.22 |  | 4.47 |  | 6,990
Weighted-average assumptions for Stock Option Plans |
|  | Stock Option Plans |
|  | Three Months Ended September 30, |  | Nine Months Ended September 30, |
|  | 2011 |  | 2010 |  | 2011 |  | 2010 |
Stock Option Plans |  |  |  |  |  |  |  |  |
Expected stock price volatility |  | 75 | % | 60 | % | 50-75% |  | 60-69% |
Risk free interest rate |  | 2.3 | % | 2.3 | % | 2.3-2.8% |  | 2.3-3.2% |
Expected term (in years) |  | 6.1 |  | 6.1 |  | 6.0 - 6.1 |  | 5.9 – 6.1 |
Weighted-average fair value of stock options granted |  | $ | 9.48 |  | $ | 10.88 |  | $10.43 |  | $13.15 |
Weighted-average assumptions for Employee Stock Purchase Plan |
|  | Employee Stock Purchase Plan |
|  | Three Months Ended September 30, |  | Nine Months Ended September 30, |
|  | 2011* |  | 2010* |  | 2011 |  | 2010 |
Employee Stock Purchase Plan |  |  |  |  |  |  |  |  |
Expected stock price volatility |  | — |  | — |  | 56 | % | 54 | %
Risk free interest rate |  | — |  | — |  | 0.1 | % | 0.3 | %
Expected term (in years) |  | — |  | — |  | 0.5 |  | 0.5 |
Weighted-average fair value of purchase rights granted under the purchase plan |  | — |  | — |  | $ | 5.96 |  | $ | 7.46 |
* No shares were issued under the Employee Stock Purchase Plans during the three months ended September 30, 2011 and 2010, respectively.
Activity related to nonvested equity stock and stock units |
Nonvested Equity Stock and Stock Units |  | Shares |  | Weighted-Average Grant-Date Fair Value |
Nonvested at December 31, 2010 |  | 718,007 |  | $ | 18.23 |
Granted |  | 293,554 |  | 18.99 |
Vested |  | (245,697 | ) | 17.59 |
Forfeited |  | (14,934 | ) | 21.76 |
Nonvested at September 30, 2011 |  | 750,930 |  | 18.67 |

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