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, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]    
Prepaid pension costs $ 0.2 $ 0.0
Pension benefit liabilities (1.6) 0.0
Postretirement benefit liabilities (75.5) (3.3)
U.S. Defined Benefit Pension Plans    
Defined Benefit Plan Disclosure [Line Items]    
Prepaid pension costs 0.1  
Pension benefit liabilities (1.3)  
Net amount recognized (1.2)  
Canadian Defined Benefit Pension Plans    
Defined Benefit Plan Disclosure [Line Items]    
Prepaid pension costs 0.1  
Pension benefit liabilities (0.3)  
Net amount recognized (0.2)  
Retiree Health and Life Insurance Plans    
Defined Benefit Plan Disclosure [Line Items]    
Accounts payable and accrued expenses (8.1) (0.2)
Postretirement benefit liabilities (75.5) (3.3)
Net amount recognized $ (83.6) $ (3.5)