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Retirement Plans and Other Post-Retirement Benefits - Additional Information (Detail)
$ in Millions
 1 Months Ended 12 Months Ended
Oct. 31, 2018
USD ($)
Oct. 31, 2018
USD ($)
Dec. 31, 2018
USD ($)
Age
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Defined Benefit Plan Disclosure [Line Items]          
Comprehensive medical plan for retiree employees eligible age to participate in health care benefit plan | Age     65    
Comprehensive medical plan for retiree employees eligible age for avail defray costs of Medicare | Age     65    
Accumulated benefit obligation for all defined benefit pension plans     $ 324.0 $ 320.7  
Defined contribution plans Employees contribution     50.00%    
Expense associated with Defined Contribution Plans     $ 0.4 0.3 $ 0.2
Minimum [Member] | Fixed Income, Cash and Cash Equivalents [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Target allocation for the plan assets     80.00%    
Maximum [Member] | Fixed Income, Cash and Cash Equivalents [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Target allocation for the plan assets     100.00%    
Pension Benefits [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Related assets transferred from existing pension plan     $ 25.7 $ 27.9  
Discount rates     4.34% 3.85%  
Pension settlement charge         7.3
Pension settlement charge settled         $ 24.2
Pension Benefits [Member] | Minimum [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Discount rates     2.05%    
Pension Benefits [Member] | Maximum [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Discount rates     4.54%    
Other Benefits [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Discount rates     4.19% 3.68%  
Other Benefits [Member] | Minimum [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Discount rates     4.11%    
Other Benefits [Member] | Maximum [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Discount rates     4.22%    
Specialty Papers [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Pension liabilities assumed $ 210.0 $ 210.0      
Retiree healthcare liabilities 38.0 38.0      
Related assets transferred from existing pension plan $ 280.0 $ 280.0