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Stock-based Compensation - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense $ 10.9 $ 11.4 $ 21.3 $ 21.6
Tax benefit from compensation expense 3.4 $ 1.6 6.3 $ 5.5
Proceeds from stock options exercised     12.9  
Tax benefit realized from exercise of stock options     9.3  
Unrecognized compensation cost 7.6   $ 7.6  
Employee Stock Option [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Period for recognition of compensation not yet recognized     2 years 2 months 26 days  
Performance Shares [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Period for recognition of compensation not yet recognized     2 years 4 months 9 days  
Compensation not yet recognized, share-based awards other than options 14.7   $ 14.7  
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     2 years 1 month 24 days  
Tax benefit realized on the vesting of restricted stock     $ 11.2  
Compensation not yet recognized, share-based awards other than options $ 29.9   $ 29.9