Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Stock Options (Schedule of Stock Options Assumptions) (Details)

v2.4.0.8
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