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
Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	805.9	$ 772.1
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	54.00%	52.00%
International Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	23.00%	25.00%
U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	20.00%	21.00%
Real Estate Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	1.00%	1.00%
Other Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	2.00%	1.00%
Packaging Corporation of America
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	285.9
Packaging Corporation of America \| Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations	62.00%
Packaging Corporation of America \| Other Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations	4.00%
Packaging Corporation of America \| Equities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations	34.00%
Boise Inc.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	520.1
Boise Inc. \| Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations	50.00%
Boise Inc. \| Equities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations	50.00%

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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

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-Section 35

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-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

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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

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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

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-Section 50

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