Annual report pursuant to Section 13 and 15(d)

Pension And Other Postretirement Benefit Programs - Amounts Recognized on the Consolidated Balance Sheets (Details)

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Pension And Other Postretirement Benefit Programs - Amounts Recognized on the Consolidated Balance Sheets (Details) - USD ($)
$ in Millions
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]    
Pension benefit liabilities $ (11.3) $ (2.3)
Postretirement benefit liabilities (55.7) (69.9)
Retiree Health and Life Insurance Plans    
Defined Benefit Plan Disclosure [Line Items]    
Accounts payable and accrued expenses (6.5) (6.5)
Postretirement benefit liabilities (55.7) (69.9)
Net amount recognized (62.2) (76.4)
U.S. Pension Plan | Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Pension benefit liabilities (9.3) (1.6)
Net amount recognized (9.3) (1.6)
Canadian Pension Plan | Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Pension benefit liabilities (2.0) (0.7)
Net amount recognized $ (2.0) $ (0.7)