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Stock-based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation expense $ 37.3 $ 38.5 $ 41.1
Tax benefit from compensation expense $ 6.7 $ 12.1 $ 14.0
Grant date fair value (in dollars per share) $ 6.78 $ 7.69 $ 5.69
Award vesting period (in years) 3 years    
Proceeds from option exercises $ 17.4 $ 24.8 $ 16.7
Tax benefit from exercise of stock options 6.6    
Intrinsic value on options exercised 33.6 42.2 42.5
Vested in period, fair value 6.8 5.2 3.4
Unrecognized compensation cost $ 3.6    
Period for recognition of compensation not yet recognized (in years) 1 year 4 months 24 days    
Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expiration period (in years) 10 years    
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 (in years) 1 year 7 months 6 days    
Restricted stock grants in period (in shares) 1.1    
Unrecognized compensation cost $ 19.3    
Aggregate intrinsic value, vested 36.2 30.1 5.5
Vested in period, fair value $ 35.3 $ 29.4 $ 6.2
Restricted Stock and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche One [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 3 years    
Restricted Stock and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Two [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 1 year    
Restricted Stock and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Three [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 2 years    
Restricted Stock and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Four [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 3 years    
Restricted Stock and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Five [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 4 years    
Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (in years) 3 years    
Period for recognition of compensation not yet recognized (in years) 1 year 8 months 12 days    
Restricted stock grants in period (in shares) 0.3    
Unrecognized compensation cost $ 10.5    
Award requisite service period (in years) 3 years    
Performance Shares [Member] | Minimum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Actual award percent 0.00%    
Performance Shares [Member] | Maximum [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Actual award percent 200.00%    
2014 Plan [Member] | Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted average dividend rate 0.00% 0.00% 0.00%