Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pkg_A4Point50SeniorNotesDueNovember2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pkg_ThreePointSixFiveSeniorNotesDueSeptemberTwoThousandAndTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pkg_ThreePointFourPercentageSeniorNotesDueDecemberTwoThousandAndTwentySevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pkg_ThreePointZeroPercentageSeniorNotesDueDecemberTwoThousandAndTwentyNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pkg_FourPointZeroFivePercentageSeniorNotesDueDecemberTwoThousandAndFortyNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pkg_ThreePointZeroFivePercentageSeniorNotesDueDecemberTwoThousandAndFiftyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Summary of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2021	Oct. 31, 2021	Oct. 08, 2021	Sep. 21, 2021	Dec. 31, 2020	Dec. 31, 2019	Nov. 21, 2019	Dec. 13, 2017	Sep. 05, 2014	Oct. 22, 2013
Debt Instrument [Line Items]
Long-term debt	$ 2,491.0				$ 2,493.7
Less unamortized debt issuance costs	19.5				14.3
Long-term debt	2,471.5				2,479.4
Line of Credit
Debt Instrument [Line Items]
Long-term debt	0.0				0.0
4.50% Senior Notes, due November 2023
Debt Instrument [Line Items]
Stated interest rate		4.50%
4.50% Senior Notes, due November 2023 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt					$ 699.4
Stated interest rate	4.50%		4.50%	4.50%	4.50%					4.50%
3.65% Senior Notes, due September 2024 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 399.6				$ 399.5
Stated interest rate	3.65%				3.65%				3.65%
3.40% Senior Notes, due December 2027 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 499.0				$ 498.8
Stated interest rate	3.40%				3.40%			3.40%
3.00% Senior Notes, due December 2029
Debt Instrument [Line Items]
Stated interest rate						3.00%
3.00% Senior Notes, due December 2029 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 499.5				$ 499.4
Stated interest rate	3.00%				3.00%		3.00%
4.05% Senior Notes, due December 2049
Debt Instrument [Line Items]
Stated interest rate						4.05%
4.05% Senior Notes, due December 2049 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 396.6				$ 396.6
Stated interest rate	4.05%				4.05%		4.05%
3.05% Senior Notes, due December 2051 \| Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 696.3				$ 0.0
Stated interest rate	3.05%				3.05%