| 
           Stockholders' Equity and Stock Based Compensation (Details) 
         | 
        3 Months Ended | 12 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|
| 
           Mar. 31, 2013
 
          Installment 
         | 
        
           Dec. 31, 2012
 
          Installment 
         | 
        
           Dec. 31, 2011
 
          Customer 
         | 
        
           Dec. 31, 2010
 
          Installment 
         | 
        
           Dec. 31, 2009
 
          Installment 
         | 
        
           Dec. 31, 2008
 
          Installment 
         | 
        
           Dec. 31, 2007
 
          Installment 
         | 
        
           Dec. 31, 2006
 
          Installment 
         | 
      |
| 
           2006 Plan 
         | 
        ||||||||
| Stock-based compensation | ||||||||
| Number of shares of common stock initially available for award | 800,000 | |||||||
| Number of shares of Common Stock available for future award grants | 0 | |||||||
| 
           2006 Plan | Restricted stock 
         | 
        ||||||||
| Stock-based compensation | ||||||||
| Granted (in shares) | 40,000 | 92,000 | 15,000 | 150,500 | 140,000 | 57,500 | 30,000 | 315,000 | 
| Forfeited (in shares) | 3,525 | 8,375 | 5,875 | 3,500 | 12,500 | |||
| Number of equal quarterly installments for vesting of awards | 16 | 20 | 20 | 20 | 20 | 20 | 20 | 20 | 
| 
           2006 Plan | Restricted stock | CEO 
         | 
        ||||||||
| Stock-based compensation | ||||||||
| Granted (in shares) | 200,000 | |||||||
| Number of equal quarterly installments for vesting of awards | 40 | |||||||
| 
           2012 Plan 
         | 
        ||||||||
| Stock-based compensation | ||||||||
| Number of shares of common stock initially available for award | 600,000 | |||||||
| Number of shares of Common Stock available for future award grants | 593,775 | |||||||