Share Based Compensation (Details) - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2019
Sep. 30, 2018
Restricted shares      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total number of restricted shares granted 196,476 1,192,145 1,904,595
Estimated fair value (in dollars per share)   $ 16.27 $ 13.81
Vested (in shares) 3,660 212,929 209,765
Restricted shares | Vesting based on time      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total number of restricted shares granted 192,816    
Vesting period from grant date 3 years    
Stock options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Granted (in shares)   31,178 359,618
Stock options | Vesting based on time      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Granted (in shares) 31,178    
Vesting period from grant date 3 years