Annual report pursuant to Section 13 and 15(d)

Pension and Other Postretirement Benefit Programs - Narrative (Details)

v3.8.0.1
Pension and Other Postretirement Benefit Programs - Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Apr. 01, 2016
Dec. 31, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]      
Defined contribution plan costs   $ 8.0 $ 7.3
Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Asset class performance period   20 years  
Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Assumed defined-benefit pension plan assets $ 381.4    
Defined benefit pension obligations 385.4    
AOCL related to pension and other postretirement benefit plans 101.8    
Retiree Health and Life Insurance Plans      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit pension obligations $ 82.9    
Health care cost trend rate assumed for next fiscal year, pre-65 retiree   7.90%  
Health care cost rate assumed by 2026   4.50%  
Expected amortization of unrecognized net actuarial losses in 2018   $ 2.4  
Retiree Health and Life Insurance Plans | Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Health care cost trend rate assumed for next fiscal year, post-65 retiree   5.70%  
Retiree Health and Life Insurance Plans | Maximum      
Defined Benefit Plan Disclosure [Line Items]      
Health care cost trend rate assumed for next fiscal year, post-65 retiree   10.70%  
U.S. Pension Plan | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Expected return on plan assets (in percentage)   6.10% 6.75%
Expected unrecognized prior service cost and net actuarial losses to be recognized in 2018   $ 10.6  
Expected employer contributions in 2018   0.1  
U.S. Pension Plan | Retiree Health and Life Insurance Plans      
Defined Benefit Plan Disclosure [Line Items]      
Expected employer contributions in 2018   $ 6.7  
Canadian Pension Plan | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Settlement charges     $ 0.3
Expected return on plan assets (in percentage)   5.40% 5.40%
Expected unrecognized prior service cost and net actuarial losses to be recognized in 2018   $ 0.3  
Expected employer contributions in 2018   $ 0.1