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Share-Based Compensation Plans - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares available to be granted 4,000,000.0    
Unrecognized share-based compensation expense $ 55.2    
Unrecognized share-based compensation expense, period of recognition 1 year 4 months 24 days    
Service-based Restricted Share Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vested, total fair value $ 25.9 $ 25.6 $ 24.6
Granted, weighted average grant date fair value (in dollars per share) $ 54.68 $ 47.48 $ 81.51
Performance-based Restricted Share Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vested, total fair value $ 12.7 $ 8.0 $ 2.4
Granted, weighted average grant date fair value (in dollars per share) $ 55.08 $ 47.54 $ 85.01
RTSR      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vested, total fair value $ 1.5 $ 0.0 $ 0.0
Granted, weighted average grant date fair value (in dollars per share) $ 67.72 $ 55.61 $ 101.13
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 1 year    
Maximum | RTSR      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 10 years