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Stock Options (Schedule of Stock Options Assumptions) (Details) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate, Minimum 0.40%    
Risk-free interest rate, Maximum 0.50%    
Expected price volitility   22.36%  
Expected price volatility, Minimum 60.70%    
Expected price volatility, Maximum 62.60%    
Dividend yield 0.00%    
Stock Options [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate   0.80%  
Risk-free interest rate, Minimum 1.40%   0.90%
Risk-free interest rate, Maximum 1.70%   1.50%
Expected option term   4 years 6 months 4 years 6 months
Expected price volitility   62.00% 55.00%
Expected price volatility, Minimum 56.00%    
Expected price volatility, Maximum 57.00%    
Dividend yield         
Weighted average grant date fair value (in dollars per share) $ 40.94 $ 22.36 $ 10.67
Minimum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected option term 2 years 6 months    
Minimum [Member] | Stock Options [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate     0.90%
Expected option term 5 years 1 month 6 days    
Maximum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected option term 3 years 8 months 12 days    
Maximum [Member] | Stock Options [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate     1.50%
Expected option term 5 years 2 months 12 days