XML 104 R88.htm IDEA: XBRL DOCUMENT
v3.20.4

Employee Benefit Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Cost and Other Comprehensive (Income) Loss (Parenthetical) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items] |
Accumulated losses, excess percentage threshold required on projected benefit obligation | 10.00%
Packaging Corporation of America | Minimum |
Defined Benefit Plan Disclosure [Line Items] |
Average remaining service period of active employees used for recognition of market-related value of assets | 7 years
Packaging Corporation of America | Maximum |
Defined Benefit Plan Disclosure [Line Items] |
Average remaining service period of active employees used for recognition of market-related value of assets | 9 years
Boise Inc. | Minimum |
Defined Benefit Plan Disclosure [Line Items] |
Average remaining lifetime of inactive participants used for recognition of market-related value of assets | 23 years
Boise Inc. | Maximum |
Defined Benefit Plan Disclosure [Line Items] |
Average remaining lifetime of inactive participants used for recognition of market-related value of assets | 26 years

X
- Definition Accumulated losses, excess percentage threshold required on projected benefit obligation. + References No definition available. + Details
Name: | pkg_AccumulatedLossesExcessPercentageThresholdRequiredOnProjectedBenefitObligation
Namespace Prefix: | pkg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average remaining lifetime of inactive participants used for recognition of market-related value of assets. + References No definition available. + Details
Name: | pkg_AverageRemainingLifetimeOfInactiveParticipantsUsedForRecognitionOfMarketRelatedValueOfAssets
Namespace Prefix: | pkg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average remaining service period of active employees used for recognition of market-related value of assets. + References No definition available. + Details
Name: | pkg_AverageRemainingServicePeriodOfActiveEmployeesUsedForRecognitionOfMarketRelatedValueOfAssets
Namespace Prefix: | pkg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=pkg_PackagingCorporationOfAmericaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=pkg_BoiseIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |