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Share-based Compensation - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expenses $ 3.6 $ 3.4 $ 7.1 $ 6.7
Restricted Stock Units        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Maximum unrecognized cost for stocks and RSU's $ 23.6   $ 23.6  
Unrecognized compensation cost, weighted average period of recognition     2 years 1 month 6 days  
Time Based Awards        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period     3 years  
Awards with Performance Conditions        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Performance adjustment percent     25.00%  
Awards with Performance Conditions | 2018 LTIP        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period     3 years  
Performance measurement period     1 year  
Requisite service period     2 years