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Employee Benefit Plans and Other Postretirement Benefits - Additional Information (Details)
shares in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
Age
shares
Dec. 31, 2016
USD ($)
shares
Dec. 31, 2015
USD ($)
Defined Benefit Plan Disclosure [Line Items]      
Accumulated other comprehensive loss $ (156,900,000) $ (139,600,000)  
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Accumulated benefit obligation for plans with obligations in excess of plan assets $ 1,200,000,000    
Weighted-Average expected return on plan assets for 2018 6.06%    
Fair value of plan assets $ 954,800,000 $ 830,400,000  
Pension Contributions [Abstract]      
Expected contribution to qualified plans (at least) $ 4,600,000    
Company's common stock | shares 1.8 2.2  
Deferred compensation liability $ 13,600,000 $ 13,700,000  
Minimum      
Pension Contributions [Abstract]      
Company's contribution to pension plan, percentage 3.00%    
Maximum      
Pension Contributions [Abstract]      
Company's contribution to pension plan, percentage 5.00%    
Fixed Income Securities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Percentage of Fair Value 21.00% 54.00%  
Other Securities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Percentage of Fair Value 64.00% 1.00%  
Boise Inc.      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Fair value of plan assets $ 551,300,000    
Boise Inc. | Equities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Target Allocation 44.00%    
Boise Inc. | Fixed Income Securities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Target Allocation 54.00%    
Boise Inc. | Other Securities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Target Allocation 2.00%    
Packaging Corporation of America      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Fair value of plan assets $ 403,500,000    
Packaging Corporation of America | Equities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Target Allocation 50.00%    
Packaging Corporation of America | Fixed Income Securities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Target Allocation 49.00%    
Packaging Corporation of America | Other Securities      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Target Allocation 1.00%    
Other(Cash) | Boise Inc.      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Percentage of Fair Value 100.00%    
Postretirement Plans      
Defined Benefit Plan Disclosure [Line Items]      
Minimum retirement age for medical benefit plan coverage | Age 58    
Minimum service period for medical benefit plan coverage, years 10 years    
Employee age after which minimum service period to be completed for medical benefit plan coverage | Age 48    
Pension Contributions [Abstract]      
Contributions to pension plan $ 1,200,000 $ 1,400,000  
Postretirement Health Coverage | Accounting Standards Update 2015-04      
Defined Benefit Plan Disclosure [Line Items]      
Benefit obligation   (5,100,000)  
Accumulated other comprehensive loss   3,100,000  
Deferred income taxes   $ 2,000,000  
Pension Plans      
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)      
Weighted-Average expected return on plan assets for 2018 6.55% 6.57% 6.73%
Fair value of plan assets $ 954,800,000 $ 830,400,000 $ 764,400,000
Pension Contributions [Abstract]      
Contributions to pension plan 43,500,000 58,200,000  
Pension Plans | Qualified      
Pension Contributions [Abstract]      
Contributions to pension plan 42,100,000 57,100,000 0
Matching Contributions      
Pension Contributions [Abstract]      
Company's contribution to defined contribution plans 42,800,000 40,400,000 37,900,000
Service Related Contributions      
Pension Contributions [Abstract]      
Company's contribution to defined contribution plans $ 22,400,000 $ 14,900,000 $ 12,400,000