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           Employee Benefit Plan (Details) (USD $) 
        In Millions, unless otherwise specified  | 
        12 Months Ended | ||
|---|---|---|---|
| 
           Dec. 31, 2011 
         | 
        
           Dec. 31, 2010 
         | 
        
           Dec. 31, 2009 
         | 
      |
| Employee Benefit Plan [Abstract] | |||
| Percentage of matching contribution of each participants | 100.00% | 100.00% | 100.00% | 
| Maximum contribution percentage of participating employees | 5.00% | 5.00% | 5.00% | 
| Company's contribution to the 401K plan | $ 1.8 | $ 1.4 | $ 1.5 | 
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- Details 
          
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- Definition 
          The increase in the fair value of plan assets from contributions made by the employer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Percentage Of Company Matches Of Employees Contributions Maximum No definition available. 
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- Definition 
          Percentage Of Employees Contributions Maximum No definition available. 
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