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Employee Benefit Plans - Accumulated Benefit Obligation and Underfunded Pension Plan Detail Narrative (Details) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]    
Defined benefit plan, accumulated benefit obligation $ 796.6 $ 737.8
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation 618.8  
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation 618.8  
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets $ 469.6