Annual report pursuant to Section 13 and 15(d)

Employee Benefits and Share Option Plans - Fair value assumptions of Share Option Awards (Details)

v3.3.1.900
Employee Benefits and Share Option Plans - Fair value assumptions of Share Option Awards (Details)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Time Based Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield
Expected stock price volatility, minimum 32.32% 48.30% 50.40%
Expected stock price volatility, maximum 45.33% 49.90% 54.80%
Risk-free interest rate, minimum 1.34% 1.80% 0.80%
Risk-free interest rate, maximum 1.92% 2.02% 1.82%
Expected term   6 years 3 months  
Time Based Options | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term 6 years   5 years
Time Based Options | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term 6 years 6 months   6 years 3 months
Performance Based Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield 0.00%    
Expected stock price volatility, minimum 29.31%    
Expected stock price volatility, maximum 29.86%    
Risk-free interest rate 1.76%    
Performance Based Options | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term 4 years 10 months 17 days    
Performance Based Options | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term 5 years 4 months 17 days    
Market Based Share Option Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield 0.00%    
Expected share price volatility 30.00%    
Risk-free interest rate 1.34%    
Expected term Mid-point from vesting to assumed options expiration