Income taxes line items.

No definition available.

Name:	pkg_IncomeTaxesLineItems
Namespace Prefix:	pkg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Tax year that remains open to examination under enacted tax laws, in YYYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-15

+ Details

Name:	us-gaap_OpenTaxYear
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:gYearListItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 217
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-217

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-15A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482525/740-10-45-10B

+ Details

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

+ References

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionAxis=pkg_BoiseIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityNameAxis=us-gaap_InternalRevenueServiceIRSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Taxes [Line Items]
Gross reserve for unrecognized tax benefits, excluding interest and penalties	$ 2.9	$ 3.2	$ 2.4	$ 1.7
Unrecognized tax benefits that would impact of effective tax rate	2.9
Interest accrued related to unrecognized tax benefits and penalties	$ 0.3	$ 0.2
Boise Inc.
Income Taxes [Line Items]
Open tax year	2008 2011 2013
Non U.S. taxing jurisdiction
Income Taxes [Line Items]
Open tax year	2019
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax year	2021 2025