Annual report pursuant to Section 13 and 15(d)

Pension And Other Postretirement Benefit Programs - Fair Value Measurement (Details)

v3.20.4
Pension And Other Postretirement Benefit Programs - Fair Value Measurement (Details) - Pension Plan - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
United States      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 417.2 $ 380.7 $ 337.1
United States | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets (0.3) (0.4)  
United States | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 417.5 381.1  
United States | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
United States | Fixed income securities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 226.5 207.9  
United States | Fixed income securities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
United States | Fixed income securities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 226.5 207.9  
United States | Fixed income securities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
United States | Equities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 191.0 173.2  
United States | Equities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
United States | Equities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 191.0 173.2  
United States | Equities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
United States | Other      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets (0.3) (0.4)  
United States | Other | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets (0.3) (0.4)  
United States | Other | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
United States | Other | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14.8 14.2 $ 13.6
Canadian Pension Plan | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.2 0.3  
Canadian Pension Plan | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14.6 13.9  
Canadian Pension Plan | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan | Fixed income securities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7.5 7.0  
Canadian Pension Plan | Fixed income securities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan | Fixed income securities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7.5 7.0  
Canadian Pension Plan | Fixed income securities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan | Equities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7.1 6.9  
Canadian Pension Plan | Equities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan | Equities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7.1 6.9  
Canadian Pension Plan | Equities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan | Other      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.2 0.3  
Canadian Pension Plan | Other | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.2 0.3  
Canadian Pension Plan | Other | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0.0 0.0  
Canadian Pension Plan | Other | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 0.0 $ 0.0