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Pension and Postretirement Benefit Costs - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]          
Net mark-to-market adjustment on actuarially determined liabilities $ 13.0 $ 0.0 $ 13.0 $ 0.0  
Postretirement benefit plans          
Defined Benefit Plan Disclosure [Line Items]          
Net mark-to-market adjustment on actuarially determined liabilities $ 13.0   $ 13.0    
Discount rate 2.70%   2.70%   3.40%
Decrease of benefit obligation for Remeasurement $ 174.5   $ 174.5    
Average remaining service period participating employees (in years)     5 years 1 month 6 days