Annual report pursuant to Section 13 and 15(d)

Pension And Other Postretirement Benefit Programs - Benefit Obligations in Excess of Assets (Details)

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Pension And Other Postretirement Benefit Programs - Benefit Obligations in Excess of Assets (Details) - Pension Plan - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
United States    
Defined-benefit pension plans with benefit obligations in excess of assets    
Projected benefit obligation, December 31 $ 2.3 $ 394.6
Accumulated benefit obligation, December 31 2.3 393.2
Fair value of plan assets, December 31 0.0 380.7
Canadian Pension Plan    
Defined-benefit pension plans with benefit obligations in excess of assets    
Projected benefit obligation, December 31 16.7 15.8
Accumulated benefit obligation, December 31 16.7 15.8
Fair value of plan assets, December 31 $ 14.4 $ 13.7