Annual report pursuant to Section 13 and 15(d)

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

v3.6.0.2
Employee Benefits and Share-Based Compensation - Fair value assumptions of Share Option Awards (Details)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Time Based Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield
Expected stock price volatility, minimum 30.36% 32.32% 48.30%
Expected stock price volatility, maximum 33.01% 45.33% 49.90%
Risk-free interest rate, minimum 1.20% 1.34% 1.80%
Risk-free interest rate, maximum 1.48% 1.92% 2.02%
Expected term 6 years   6 years 3 months
Time Based Options | Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term   6 years  
Time Based Options | Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term   6 years 6 months  
Performance Based Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield  
Expected stock price volatility, minimum 25.97% 29.31%  
Expected stock price volatility, maximum 30.21% 29.86%  
Risk-free interest rate, minimum 1.01%    
Risk-free interest rate, maximum 1.93%    
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 4 months 17 days 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 1 month 17 days 5 years 4 months 17 days  
Market Based Share Option Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield    
Expected share price volatility   30.00%  
Risk-free interest rate   1.34%  
Expected term   Mid-point from vesting to assumed options expiration