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Stock-based Compensation - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based compensation $ 4.2 $ 9.4 $ 9.5 $ 27.5
Tax benefit from compensation expense 0.4 $ 1.8 1.5 5.2
Proceeds from stock options exercised     46.0 $ 17.2
Tax benefit realized from exercise of stock options     11.3  
Unrecognized compensation cost 3.9   3.9  
Employee Stock Option [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Proceeds from stock options exercised     $ 46.0  
Period for recognition of compensation not yet recognized     1 year 6 months  
Restricted Stock and Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Period for recognition of compensation not yet recognized     1 year 6 months  
Tax benefit realized on the vesting of restricted stock     $ 0.3  
Compensation not yet recognized, share-based awards other than options 16.4   $ 16.4  
Performance Shares [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Period for recognition of compensation not yet recognized     2 years 1 month 6 days  
Compensation not yet recognized, share-based awards other than options $ 8.2   $ 8.2