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Employee Benefit Plans and Other Postretirement Plans - Schedule of Pension Plan Asset Investments and Target Allocations (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
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Dec. 31, 2014 | Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 805.9 us-gaap_DefinedBenefitPlanFairValueOfPlanAssets | $ 772.1 us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Debt Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Fair Value | 54.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_DebtSecuritiesMember | 52.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_DebtSecuritiesMember
International Equity Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Fair Value | 23.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_InternationalEquitySecuritiesMember | 25.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_InternationalEquitySecuritiesMember
U.S. Equity Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Fair Value | 20.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_USEquitySecuritiesMember | 21.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_USEquitySecuritiesMember
Real Estate Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Fair Value | 1.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_RealestatesecuritiesMember | 1.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_RealestatesecuritiesMember
Other Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Fair Value | 2.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_OtherSecuritiesMember | 1.00%us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_OtherSecuritiesMember
Packaging Corporation of America |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 285.9 us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / dei_LegalEntityAxis = pkg_PackagingCorporationofAmericaMember |
Packaging Corporation of America | Debt Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocations | 62.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_DebtSecuritiesMember / dei_LegalEntityAxis = pkg_PackagingCorporationofAmericaMember |
Packaging Corporation of America | Other Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocations | 4.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = pkg_OtherSecuritiesMember / dei_LegalEntityAxis = pkg_PackagingCorporationofAmericaMember |
Packaging Corporation of America | Equities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocations | 34.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / dei_LegalEntityAxis = pkg_PackagingCorporationofAmericaMember |
Boise Inc. |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair value of plan assets | 520.1 us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / dei_LegalEntityAxis = pkg_BoiseInc.Member |
Boise Inc. | Debt Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocations | 50.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_DebtSecuritiesMember / dei_LegalEntityAxis = pkg_BoiseInc.Member |
Boise Inc. | Equities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocations | 50.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = us-gaap_EquitySecuritiesMember / dei_LegalEntityAxis = pkg_BoiseInc.Member |

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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930 + Details
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- Definition Target allocation of investments of this type to total plan assets presented on a weighted average basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(i) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920 + Details
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- Definition Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920 + Details
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