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Employee Benefit Plans and Other Postretirement Benefits - Additional Information (Details) - USD ($)
shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax):      
Accumulated benefit obligation for plans with obligations in excess of plan assets $ 1,400.0    
Weighted-Average expected return on plan assets for 2021 4.91%    
Pension Contributions [Abstract]      
Company's common stock 1.2 1.5  
Deferred compensation liability $ 22.6 $ 17.4  
Minimum      
Pension Contributions [Abstract]      
Company's contribution to pension plan, percentage 3.00%    
Maximum      
Pension Contributions [Abstract]      
Company's contribution to pension plan, percentage 5.00%    
Pension Plans      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax):      
Weighted-Average expected return on plan assets for 2021 5.29% 6.06% 6.06%
Pension Contributions [Abstract]      
Contributions to pension plan $ 83.7 $ 58.9  
Pension Plans | Qualified Plan      
Pension Contributions [Abstract]      
Contributions to pension plan 82.5 57.9 $ 21.8
Matching Contributions      
Pension Contributions [Abstract]      
Company's contribution to defined contribution plans 40.8 39.0 36.8
Service Related Contributions      
Pension Contributions [Abstract]      
Company's contribution to defined contribution plans $ 39.4 $ 36.7 $ 33.3