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Stock-Based Compensation (Details 2) (Employee Stock [Member])
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Summary of fair value of the employee stock options and ESPP plan      
Expected dividend yield of stock 0.00% 0.00% 0.00%
Maximum [Member]
     
Summary of fair value of the employee stock options and ESPP plan      
Risk-free interest rate 0.30% 0.61% 1.00%
Expected life of option (in years) 2 years 2 years 2 years
Expected volatility 1.37% 0.85% 1.14%
Minimum [Member]
     
Summary of fair value of the employee stock options and ESPP plan      
Risk-free interest rate 0.05% 0.05% 0.20%
Expected life of option (in years) 6 months 6 months 6 months
Expected volatility 0.93% 0.58% 0.62%