Packaging Corporation of America (PKG) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 02, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	PKG
Entity Registrant Name	PACKAGING CORP OF AMERICA
Entity Central Index Key	75,677
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		94,497,298

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017		Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales		$ 1,809.9	$ 1,640.1	[1]	$ 5,268.1	$ 4,760.6	[1]
Cost of sales		(1,366.7)	(1,243.1)		(4,048.2)	(3,661.2)
Gross profit		443.2	397		1,219.9	1,099.4
Selling, general and administrative expenses		(134.2)	(129.6)		(406.7)	(386.9)
Other expense, net		(10.5)	(24.8)		(32.2)	(32.4)
Income from operations	[2]	298.5	242.6		781	680.1
Interest expense, net and other	[2]	(24.4)	(25.7)		(75)	(75.5)
Income before taxes	[2]	274.1	216.9		706	604.6
Provision for income taxes		(67.4)	(77.8)		(172.6)	(204.9)
Net income		$ 206.7	$ 139.1		$ 533.4	$ 399.7
Net income per common share:
Basic		$ 2.19	$ 1.47		$ 5.65	$ 4.24
Diluted		2.18	1.47		5.64	4.23
Dividends declared per common share		$ 0.79	$ 0.63		$ 2.21	$ 1.89
Statements of Comprehensive Income:
Net income		$ 206.7	$ 139.1		$ 533.4	$ 399.7
Foreign currency translation adjustment			0.1		(0.1)	(0.2)
Reclassification adjustments to cash flow hedges included in net income, net of tax of $0.3 million, $0.5 million, $1.0 million, and $1.6 million		1	0.9		3	2.6
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $1.0 million, $1.2 million, $3.0 million, and $3.7 million		3	1.9		8.9	6.2
Other comprehensive income		4	2.9		11.8	8.6
Comprehensive income		$ 210.7	$ 142		$ 545.2	$ 408.3
[1]	Prior periods have not been adjusted under the modified retrospective method for Topic 606.
[2]	(a)Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, New and Recently Adopted Accounting Standards, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Three Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Three Months Ended September 30, 2017 Adjusted Packaging $261.5 $1.7 $263.2 Paper (0.7) (1.9) (2.6) Corporate (18.5) 0.5 (18.0) Income from operations 242.3 0.3 242.6 Interest expense, net and other (25.4) (0.3) (25.7) Income before taxes $216.9 $— $216.9 Segment income (loss) Nine Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Nine Months Ended September 30, 2017 Adjusted Packaging $676.8 $4.9 $681.7 Paper 58.1 (5.6) 52.5 Corporate (55.7) 1.6 (54.1) Income from operations 679.2 0.9 680.1 Interest expense, net and other (74.6) (0.9) (75.5) Income before taxes $604.6 $— $604.6

Consolidated Statements of In_2

Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Reclassification adjustments to cash flow hedges included in net income, tax	$ 0.3	$ 0.5	$ 1	$ 1.6
Amortization of pension and postretirement plans actuarial loss and prior service cost, tax	$ 1	$ 1.2	$ 3	$ 3.7

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 293.8	$ 216.9
Accounts receivable, net of allowance for doubtful accounts and customer deductions of $14.0 million and $12.6 million as of September 30, 2018, and December 31, 2017, respectively	986.2	830.7
Inventories	780.6	762.5
Prepaid expenses and other current assets	49	35.5
Federal and state income taxes receivable	5.1	69.5
Total current assets	2,114.7	1,915.1
Property, plant, and equipment, net	3,065.1	2,924.9
Goodwill	888.7	883.2
Other intangible assets, net	373.9	410
Other long-term assets	57.6	64.3
Total assets	6,500	6,197.5
Current liabilities:
Current maturities of long-term debt	0	150
Capital lease obligations	1.4	1.3
Accounts payable	438.9	402.9
Dividends payable	75.8	60.5
Accrued liabilities	223.4	203.2
Accrued interest	27	14.8
Total current liabilities	766.5	832.7
Long-term liabilities:
Long-term debt	2,482.9	2,480.4
Capital lease obligations	17.9	19
Deferred income taxes	279.3	239.5
Compensation and benefits	360.2	372.5
Other long-term liabilities	63	70.8
Total long-term liabilities	3,203.3	3,182.2
Commitments and contingent liabilities
Stockholders' equity:
Common stock, par value $0.01 per share, 300.0 million shares authorized, 94.5 million and 94.3 million shares issued as of September 30, 2018, and December 31, 2017, respectively	0.9	0.9
Additional paid in capital	488.9	471.2
Retained earnings	2,185.5	1,867.4
Accumulated other comprehensive loss	(145.1)	(156.9)
Total stockholders' equity	2,530.2	2,182.6
Total liabilities and stockholders' equity	$ 6,500	$ 6,197.5

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts and customer deductions	$ 14	$ 12.6
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	94,500,000	94,300,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 533.4	$ 399.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	313.6	283.7
Amortization of deferred financing costs	6.5	6
Share-based compensation expense	17.4	15.4
Deferred income tax provision	34.9	1.6
Net loss on impairment of assets		13.5
Pension and post-retirement benefits expense, net of contributions	(2.7)	(25.3)
Other, net	8.2	12
Increase in assets —
Accounts receivable	(148.9)	(142.2)
Inventories	(22.6)	(13)
Prepaid expenses and other current assets	(13.2)	(10.3)
Increase (decrease) in liabilities —
Accounts payable	19.6	37.7
Accrued liabilities	23.7	9.6
Federal and state income taxes payable / receivable	64.6	(5.1)
Net cash provided by operating activities	834.5	583.3
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(404.3)	(226.2)
Additions to other long term assets	(4.1)	(6.9)
Proceeds from disposals	0.5	4.4
Other, net	2.6	1.1
Net cash used for investing activities	(405.3)	(227.6)
Cash Flows from Financing Activities:
Repayments of debt and capital lease obligations	(151)	(35.6)
Common stock dividends paid	(193.4)	(178.2)
Shares withheld to cover employee restricted stock taxes	(7.9)	(10.7)
Net cash used for financing activities	(352.3)	(224.5)
Net increase in cash and cash equivalents	76.9	131.2
Cash and cash equivalents, beginning of period	216.9	239.3
Cash and cash equivalents, end of period	$ 293.8	$ 370.5

Nature of Operations and Basis

Nature of Operations and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations and Basis of Presentation	1. Nature of Operations and Basis of Presentation Packaging Corporation of America ("we," "us," "our," PCA," or the "Company") was incorporated on January 25, 1999. In April 1999, PCA acquired the containerboard and corrugated packaging products business of Pactiv Corporation (Pactiv), formerly known as Tenneco Packaging, Inc., a wholly owned subsidiary of Tenneco Inc. We are a large diverse manufacturer of both packaging and paper products. We are headquartered in Lake Forest, Illinois and we operate primarily in the United States. We report our business in three reportable segments: Packaging, Paper, and Corporate and Other. Our Packaging segment produces a wide variety of corrugated packaging products. The Paper segment manufactures and sells a range of communication-based papers. During the second quarter of 2018, the Company discontinued the production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill and converted the No. 3 machine to a virgin kraft linerboard machine. Subsequent to the date of conversion in May 2018, operating results for the Wallula mill are primarily included in the Packaging segment. Corporate and other includes support staff services and related assets and liabilities, transportation assets, and activity related to other ancillary support operations. For more information about our segments, see Note 18 Segment Information. In these consolidated financial statements, certain amounts in prior periods' consolidated financial statements have been reclassified to conform with the current period presentation. The consolidated financial statements of PCA as of September 30, 2018 and for the three and nine months ended September 30, 2018 and 2017 are unaudited but include all adjustments (consisting only of normal recurring adjustments) that management considers necessary for a fair presentation of such financial statements. The preparation of the consolidated financial statements involves the use of estimates and accruals. Actual results may vary from those estimates. These financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete audited financial statements. Operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. These consolidated financial statements should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2017. The consolidated financial statements include the accounts of PCA and its majority-owned subsidiaries after elimination of intercompany balances and transactions.

New and Recently Adopted Accoun

New and Recently Adopted Accounting Standards	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
New and Recently Adopted Accounting Standards	2. New and Recently Adopted Accounting Standards Recently Adopted Accounting Standards Effective January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) 2014-09 (Topic 606): Revenue from Contracts with Customers Revenue Recognition a. The Company ships a portion of its products to customers under consignment agreements. These products do not have an alternative use, and, under the new standard, revenue associated with these products is required to be recognized earlier than under prior revenue recognition standards. Utilizing the modified retrospective method, the cumulative impact of adopting the new standard resulted in an increase of approximately $1.6 million, net of tax, to opening retained earnings as of January 1, 2018. b. The new revenue standard also provides additional clarity concerning contract fulfillment costs, which resulted in certain costs being classified as cost of sales rather than selling, general and administrative expenses beginning January 1, 2018. For the three and nine months ended September 30, 2018, this amount totaled $6.9 million and $20.0 million, respectively. See Note 3, Revenue, for more information. Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. are required to be presented in the income statement separately from the service cost component and outside the subtotal of operating income. The update also allows only the service cost component to be eligible for capitalization for internally developed capital projects. The amendments in this update are applied retrospectively for the income statement presentations and prospectively for the capitalization of service costs. The adoption of this ASU retrospectively resulted in a $0.3 million and $0.9 million reclassification between cost of sales and selling, general and administrative expenses (both components of income from operations) and interest expense, net and other (a component outside of income from operations) for the three and nine months ended September 30, 2017, respectively. Effective January 1, 2018, the Company adopted ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , which clarifies what changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. T Effective January 1, 2018, the Company adopted Clarifying the Definition of a Business Effective January 1, 2018, the Company adopted Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments New Accounting Standards Not Yet Adopted In August 2018, the issued ASU 2018-14, Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans . ASU 2018-14 removes certain disclosures that are not considered cost beneficial, clarifies certain required disclosures and adds additional disclosures. The ASU is effective for annual periods beginning after December 31, 2020, with early adoption permitted. The amendments in ASU 2018-14 would need to be applied on a retrospective basis. The Company is currently evaluating the impact this guidance will have on its related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. The Company is currently evaluating the impact of the new guidance. In February 2018, the FASB issued ASU 2018-02 (Topic 220): Income Statement – R eporting Comprehensive Income – Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which allows for optional reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects resulting from the enactment of H.R.1 (P.L. 115-97), originally known as the “Tax Cuts and Jobs Act,” in December 2017. An entity that elects to reclassify these amounts must reclassify stranded tax effects related to the change in federal tax rate for all items accounted for in other comprehensive income (e.g., pension and postretirement benefits and cash flow hedges). Entities may also elect to reclassify other stranded tax effects that relate to the Act but do not directly relate to the change in the federal tax rate (e.g., state taxes). Upon adoption of ASU 2018-02, entities are required to disclose their policy for releasing the income tax effects from accumulated other comprehensive income. ASU 2018-02 is effective for annual periods beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect this ASU to have a material impact on the Company’s financial position, results of operations, or cash flow. In February 2016, the FASB issued ASU 2016-02 (Topic 842): Leases Codification Improvements to Topic 842, Leases Leases (Topic 842): Targeted Improvements ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and early adoption is permitted. We are in the process of implementing changes to our systems and processes in conjunction with our review of existing lease agreements, which primarily consist of equipment and real estate leases. In addition, we are currently working with a vendor to implement a technology tool to assist with the accounting and reporting requirements of the new standard. We will adopt Topic 842 effective January 1, 2019 and expect to elect certain available transitional practical expedients. We are still in the process of determining the effects on our financial statements but do expect to recognize a liability and corresponding asset associated with in-scope operating leases. There were no other accounting standards recently issued that had or are expected to have a material impact on our financial position or results of operations.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2018
Revenue From Contract With Customer [Abstract]
Revenue	3. Revenue Revenue Recognition Revenue is recognized when control of the promised goods or services is transferred to customers in an amount that reflects the consideration expected to be entitled in exchange for those goods or services. Sales, value added, and other taxes collected concurrently with revenue-producing activities are excluded from revenue. The following table presents our revenues disaggregated by product line (dollars in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 (a) 2018 2017 (a) Packaging $ 1,535.1 $ 1,346.6 $ 4,434.2 $ 3,915.0 Paper 254.3 271.4 774.5 784.3 Corporate and other 20.5 22.1 59.4 61.3 Total revenue $ 1,809.9 $ 1,640.1 $ 5,268.1 $ 4,760.6 (a) Prior periods have not been adjusted under the modified retrospective method for Topic 606. Packaging Revenue Our containerboard mills produce linerboard and semi-chemical corrugating medium which are papers primarily used in the production of corrugated products. The majority of our containerboard production is used internally by our corrugated products manufacturing facilities. The remaining containerboard is sold to outside domestic and export customers. Our corrugated products manufacturing plants produce a wide variety of corrugated packaging products and retail merchandise displays. We sell corrugated products to national, regional and local accounts, which are broadly diversified across industries and geographic locations. The Company recognizes revenue for its packaging products when performance obligations under the terms of a contract with a customer are satisfied. This occurs with the transfer of control of our products at a specific point in time. Based on our express terms and conditions of the sale of products to our customers, as well as terms included in contractual arrangements with our customers, we do not have an enforceable right of payment that includes a reasonable profit throughout the duration of the contract for products that do not have an alternative use. Revenue is recognized when the product is shipped from the mill or from our manufacturing facility to our customer. Certain customers may receive volume-based incentives, which are accounted for as variable consideration. We estimate these amounts based on the expected amount to be provided to customers and reduce revenue recognized. Certain customers receive a portion of their packaging products as consigned inventory with billing triggered once the customer uses or consumes the designated product. Prior to invoicing, these amounts are handled as unbilled receivables. Total unbilled receivables, which are immaterial in amount, are included in the accounts receivable financial statement caption. Paper Revenue We manufacture and sell a range of communication-based papers. Communication papers consist of cut-size office papers, and printing and converting papers. Pressure sensitive papers, including release liners, are used for specialty applications such as consumer and commercial product labels. The Company recognizes revenue for its paper products when performance obligations under the terms of a contract with a customer are satisfied. This occurs with the transfer of control of our products at a specific point in time. Revenue is recognized when the product is shipped from the mill or from our manufacturing facility or distribution center to our customer. Certain customers may receive volume-based incentives, which are accounted for as variable consideration. We estimate these amounts based on the expected amount to be provided to customers and reduce revenue recognized. Corporate and Other Revenue Revenue in this segment primarily relates to Louisiana Timber Procurement Company, L.L.C. (LTP), a variable-interest entity that is 50% owned by PCA and 50% owned by Boise Cascade Company (Boise Cascade). PCA is the primary beneficiary of LTP and has the power to direct the activities that most significantly affect the economic performance of LTP. Therefore, we consolidate 100% of LTP in our financial statements. See Note 17, Transactions With Related Parties, for more information related to LTP. The Company recognizes revenue within this segment when performance obligations under the terms of a contract with a customer are satisfied. This occurs with the transfer of control of our products at a specific point in time. Practical Expedients and Exemption Shipping and handling fees billed to a customer are recorded on a gross basis in "Net sales" with the corresponding shipping and handling costs included in "Cost of sales" in the concurrent period as the revenue is recorded. We expense sales commissions when incurred because the amortization period is one year or less. Sales commissions are recorded in "Selling, general, and administrative expenses". We do not disclose the value of unsatisfied performance obligations for contracts with an original expected duration of one year or less.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	4 . Acquisitions Sacramento Container Acquisition On October 2, 2017, PCA acquired substantially all of the assets of Sacramento Container Corporation, and 100% of the membership interests of Northern Sheets, LLC and Central California Sheets, LLC (collectively referred to as “Sacramento Container”) for a purchase price of $274 million, including working capital adjustments. Funding for the $274 million purchase price came from available cash on hand. Assets acquired include full-line corrugated products and sheet feeder operations in both McClellan, California and Kingsburg, California. Sacramento Container provides packaging solutions to customers serving portions of California’s strong agricultural market. Sacramento Container’s financial results are included in the Packaging segment from the date of acquisition. The Company accounted for the Sacramento Container acquisition using the acquisition method of accounting in accordance with ASC 805, Business Combinations 12/31/2017 Allocation Adjustments Revised Allocation Goodwill $ 151.1 $ 5.5 $ 156.6 Other intangible assets 72.6 (5.5 ) 67.1 Property, plant and equipment 26.7 — 26.7 Other net assets 23.4 — 23.4 Net assets acquired $ 273.8 $ — $ 273.8 During the second quarter ended June 30, 2018, we made a $5.5 million net adjustment based on the final valuation of the intangible assets. We recorded the adjustment as a decrease to other intangible assets with an offset to goodwill. Goodwill is calculated as the excess of the purchase price over the fair value of the net assets acquired. Among the factors that contributed to the recognition of goodwill were Sacramento Container’s commitment to continuous improvement and regional synergies, as well as the expected increases in PCA’s containerboard integration levels. Goodwill is deductible for tax purposes. Other intangible assets, primarily customer relationships, were assigned an estimated weighted average useful life of 9.6 years. Property, plant, and equipment were assigned estimated useful lives ranging from one to 13 years.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	5 . Earnings Per Share The following table sets forth the computation of basic and diluted income per common share for the periods presented (dollars and shares in millions, except per share data): Three Months Ended Nine Months Ended September 30, September 30, Numerator: 2018 2017 2018 2017 Net income $ 206.7 $ 139.1 $ 533.4 $ 399.7 Less: distributed and undistributed earnings allocated to participating securities (1.6 ) (1.1 ) (4.1 ) (3.4 ) Net income attributable to common shareholders $ 205.1 $ 138.0 $ 529.3 $ 396.3 Denominator: Weighted average basic common shares outstanding 93.7 93.6 93.7 93.5 Effect of dilutive securities 0.3 0.2 0.2 0.2 Weighted average diluted common shares outstanding 94.0 93.8 93.9 93.7 Basic income per common share $ 2.19 $ 1.47 $ 5.65 $ 4.24 Diluted income per common share $ 2.18 $ 1.47 $ 5.64 $ 4.23

Other Income (Expense), Net

Other Income (Expense), Net	9 Months Ended
	Sep. 30, 2018
Other Income And Expenses [Abstract]
Other Income (Expense), Net	6 . Other Income (Expense), Net The components of other income (expense), net, were as follows (dollars in millions): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Asset disposals and write-offs $ (5.1 ) $ (3.9 ) $ (14.4 ) $ (8.6 ) Wallula mill restructuring (a) (3.7 ) (22.7 ) (11.6 ) (22.7 ) Facilities closure and other costs (b) (1.5 ) (0.9 ) (1.6 ) (1.9 ) Acquisition and integration related costs (c) (0.1 ) (0.5 ) (0.1 ) (0.8 ) Insurance deductible for property damage (d) (0.5 ) — (0.5 ) — DeRidder mill incident (e) — 2.6 — 0.1 Hexacomb working capital adjustment (f) — — — 2.3 Other 0.4 0.6 (4.0 ) (0.8 ) Total $ (10.5 ) $ (24.8 ) $ (32.2 ) $ (32.4 ) (a) Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine. (b) For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes charges consisting of closure costs related to corrugated products facilities and a paper administration facility and costs related to a lump sum settlement payment of a multiemployer pension plan for one of our corrugated products facilities. (c) Includes charges related to recent acquisitions and the integration of recent acquisitions. (d) For 2018, includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities. (e) Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill. (f) Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	7 . Income Taxes On December 22, 2017, the President signed into law H.R.1 (P.L. 115-97), originally known as the “Tax Cuts and Jobs Act” (the “Tax Act”). The Tax Act significantly revises the U.S. tax code by, among other items, reducing the federal corporate tax rate from 35% to 21%, providing for the full expensing of certain depreciable property, eliminating the corporate alternative minimum tax, limiting the deductibility of interest expense, further limiting the deductibility of certain executive compensation, limiting the use of net operating loss carryforwards created in tax years beginning after December 31, 2017, and implementing a territorial tax system imposing a deemed repatriation transition tax (“Transition Tax”) on earnings of foreign subsidiaries. The SEC staff issued Staff Accounting Bulletin (“SAB”) 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, During the three and nine months ended September 30, 2018, we have recorded an immaterial favorable adjustment for the Transition Tax originally recorded with the measurement period provisional estimates at December 31, 2017. We expect to record our final adjustment for the income tax effects of the Tax Act after the completion and filing of our 2017 federal and state income tax returns during the fourth quarter and before the SAB 118 measurement period ends. We estimate this final adjustment, primarily from favorable timing item differences, to also be immaterial. For the three months ended September 30, 2018 and 2017, we recorded $67.4 million and $77.8 million of income tax expense and had an effective tax rate of 24.6% and 35.9%, respectively. For the nine months ended September 30, 2018 and 2017, we recorded $172.6 million and $204.9 million of income tax expense and had an effective tax rate of 24.4% and 33.9%, respectively. The decrease in our effective tax rate for both the three and nine months ended September 30, 2018 compared with the same periods in 2017 was primarily due to the Tax Act (P.L. 115-97), which included a reduction in the federal tax rate of 14.0% offset by the loss of the Domestic Production Activities Deduction benefit of about 3.2% and a reduction in the federal benefit of state tax deductions of about 0.8%, as well as an internal legal entity consolidation that took place in the third quarter of 2017, partially offset by lower excess tax benefits from employee share-based payment awards under ASU 2016-09 in 2018 compared to the same periods in 2017. Our effective tax rate may differ from the federal statutory income tax rate of 21.0% due primarily to the effect of state and local income taxes. During the three and nine months ended September 30, 2018, there were no significant changes to our uncertain tax positions. For more information, see Note 6, Income Taxes, of the Notes to Consolidated Financial Statements in “Part II, Item 8. Financial Statements and Supplementary Data” of our 2017 Annual Report on Form 10-K.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Inventories	8 . Inventories We value our raw materials, work in process, and finished goods inventories using lower of cost, as determined by the average cost method, or market. Supplies and materials are valued at the first-in, first-out (FIFO) or average cost methods. The components of inventories were as follows (dollars in millions): September 30, December 31, 2018 2017 Raw materials $ 317.9 $ 279.8 Work in process 14.9 12.6 Finished goods 180.4 217.0 Supplies and materials 267.4 253.1 Inventories $ 780.6 $ 762.5

Property, Plant, and Equipment

Property, Plant, and Equipment	9 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Property, Plant, and Equipment	9 . Property, Plant, and Equipment The components of property, plant, and equipment were as follows (dollars in millions): September 30, December 31, 2018 2017 Land and land improvements $ 162.0 $ 156.0 Buildings 756.2 729.8 Machinery and equipment 5,356.7 5,162.5 Construction in progress 240.6 194.5 Other 72.8 68.4 Property, plant and equipment, at cost 6,588.3 6,311.2 Less accumulated depreciation (3,523.2 ) (3,386.3 ) Property, plant, and equipment, net $ 3,065.1 $ 2,924.9 Depreciation expense for the three months ended September 30, 2018 and 2017 was $89.0 million and $87.0 million, respectively. During the nine months ended September 30, 2018 and 2017, depreciation expense was $275.3 million and $253.0 million, respectively. We recognized $14.0 million At September 30, 2018 and December 31, 2017, purchases of property, plant, and equipment included in accounts payable were $46.2 million and $29.8 million, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	10 . Goodwill and Intangible Assets Goodwill Goodwill represents the excess of the cost of an acquired business over the fair value of the identifiable tangible and intangible assets acquired and liabilities assumed in a business combination. At September 30, 2018 and December 31, 2017 we had $833.5 million and $828.0 million of goodwill recorded in our Packaging segment, respectively. At both September 30, 2018 and December 31, 2017, we had $55.2 million of goodwill recorded in our Paper segment. Changes in the carrying amount of our goodwill are as follows (dollars in millions): Goodwill Balance at January 1, 2018 $ 883.2 Acquisitions (a) 5.5 Balance at September 30, 2018 $ 888.7 (a) During the nine months ended September 30, 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container. Intangible Assets Intangible assets are primarily comprised of customer relationships and trademarks and trade names. The weighted average remaining useful life, gross carrying amount, and accumulated amortization of our intangible assets were as follows (dollars in millions): September 30, 2018 December 31, 2017 Weighted Average Remaining Useful Life (in Years) Gross Carrying Amount Accumulated Amortization Weighted Average Remaining Useful Life (in Years) Gross Carrying Amount Accumulated Amortization Customer relationships (a) 11.2 $ 491.4 $ 135.5 11.8 $ 497.8 $ 109.8 Trademarks and trade names (a) 10.4 33.9 17.6 9.8 32.9 13.2 Other (a) 3.1 4.3 2.6 3.6 4.3 2.0 Total intangible assets (excluding goodwill) 11.1 $ 529.6 $ 155.7 11.7 $ 535.0 $ 125.0 (a) In connection with the October 2017 acquisition of Sacramento Container, the Company recorded intangible assets of $68.4 million for customer relationships, $4.1 million for trade names, and $0.1 million for other intangibles. During the second quarter ended June 30, 2018, the Company made a $5.5 million net adjustment based on the final valuation received for the intangible assets. This adjustment resulted in a revision to the original allocations for customer relationships and trade names. As of June 30, 2018, the revised allocations for customer relationships and trade names were $61.9 million and $5.1 million, respectively. During the three months ended September 30, 2018 and 2017, amortization expense was $10.2 million and $8.4 million, respectively. During the nine months ended September 30, 2018 and 2017, amortization expense was $30.7 million and $25.3 million, respectively.

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2018
Accrued Liabilities Current And Noncurrent [Abstract]
Accrued Liabilities	11 . Accrued Liabilities The components of accrued liabilities were as follows (dollars in millions): September 30, December 31, 2018 2017 Compensation and benefits $ 131.1 $ 127.5 Medical insurance and workers’ compensation 27.0 23.9 Customer volume discounts and rebates 21.5 23.4 Franchise, property, sales and use taxes 21.3 16.0 Environmental liabilities and asset retirement obligations 4.7 4.0 Severance, retention, and relocation 3.3 3.1 Other 14.5 5.3 Total $ 223.4 $ 203.2

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	12 . Debt At September 30, 2018 and December 31, 2017, our long-term debt and interest rates on that debt were as follows (dollars in millions): September 30, 2018 December 31, 2017 Amount Interest Rate Amount Interest Rate 6.50% Senior Notes due March 2018 $ — — % $ 150.0 6.50 % 2.45% Senior Notes, net of discount of $0.4 million and $0.5 million as of September 30, 2018 and December 31, 2017, respectively, due December 2020 499.6 2.45 % 499.5 2.45 % 3.90% Senior Notes, net of discount of $0.1 million and $0.2 million as of September 30, 2018 and December 31, 2017, respectively, due June 2022 399.9 3.90 % 399.8 3.90 % 4.50% Senior Notes, net of discount of $1.1 million and $1.2 million as of September 30, 2018 and December 31, 2017, respectively, due November 2023 698.9 4.50 % 698.8 4.50 % 3.65% Senior Notes, net of discount of $0.7 million and $0.8 million as of September 30, 2018 and December 31, 2017, respectively, due September 2024 399.3 3.65 % 399.2 3.65 % 3.40% Senior Notes, net of discount of $1.5 million and $1.6 million as of September 30, 2018 and December 31, 2017, respectively, due December 2027 498.5 3.40 % 498.4 3.40 % Total 2,496.2 3.64 % 2,645.7 3.80 % Less current portion — — % 150.0 6.50 % Less unamortized debt issuance costs 13.3 15.3 Total long-term debt $ 2,482.9 3.64 % $ 2,480.4 3.64 % During the nine months ended September 30, 2018, we used cash on hand to repay debt outstanding of $150.0 million under the 6.50% Senior Notes due March 2018. For the nine months ended September 30, 2018 and 2017, cash payments for interest were $58.6 million Included in interest expense, net and other, are amortization of treasury lock settlements and amortization of financing costs. For the three months ended September 30, 2018 and 2017, amortization of treasury lock settlements was $1.3 million At September 30, 2018, we had $2,496.2 million of fixed-rate senior notes outstanding. The fair value of our fixed-rate debt was estimated to be $2,478.0 million. The difference between the book value and fair value is due to the difference between the period-end market interest rate and the stated rate of our fixed-rate debt. We estimated the fair value of our fixed-rate debt using quoted market prices (Level 2 inputs) within the fair value hierarchy, which is further defined in Note 2, Summary of Significant Accounting Policies, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2017 Annual Report on Form 10-K. For more information on our long-term debt and interest rates on that debt, see Note 9, Debt, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2017 Annual Report on Form 10-K.

Employee Benefit Plans and Othe

Employee Benefit Plans and Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans and Other Postretirement Benefits	13 . Employee Benefit Plans and Other Postretirement Benefits The components of net periodic benefit cost for our pension plans were as follows (dollars in millions): Pension Plans Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Service cost $ 6.3 $ 5.8 $ 18.8 $ 18.0 Interest cost 10.6 10.4 31.8 31.1 Expected return on plan assets (14.2 ) (13.5 ) (42.5 ) (40.5 ) Net amortization of unrecognized amounts Prior service cost 1.8 1.4 5.2 4.4 Actuarial loss 2.3 1.9 7.0 5.7 Net periodic benefit cost $ 6.8 $ 6.0 $ 20.3 $ 18.7 PCA makes pension plan contributions that are sufficient to fund its actuarially determined costs, generally equal to the minimum amounts required by the Employee Retirement Income Security Act (ERISA). From time to time, PCA may make additional discretionary contributions based on the funded status of the plans, tax deductibility, income from operations, and other factors. During the three and nine months ended September 30, 2018 and 2017, payments to our nonqualified pension plans were insignificant. For the three and nine months ended September 30, 2018, we made contributions of $18.0 million and $21.2 million, respectively, to our qualified pension plans, which exceeded our 2018 minimum pension contributions of $4.6 million. We made contributions of $36.2 million and $42.1 million to our qualified plans during the three and nine months ended September 30, 2017, respectively. The components of net periodic benefit cost for our postretirement plans were as follows (dollars in millions): Postretirement Plans Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Service cost $ 0.1 $ 0.1 $ 0.2 $ 0.2 Interest cost 0.1 0.2 0.4 0.5 Net amortization of unrecognized amounts Prior service cost (0.1 ) (0.1 ) (0.2 ) (0.1 ) Actuarial income — (0.1 ) (0.1 ) (0.1 ) Net periodic benefit cost $ 0.1 $ 0.1 $ 0.3 $ 0.5

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2018
Share Based Compensation [Abstract]
Share-Based Compensation	14 . Share-Based Compensation The Company has a long-term equity incentive plan, which allows for grants of restricted stock, performance awards, stock appreciation rights, and stock options to directors, officers, and employees, as well as others who engage in services for PCA. The plan, as amended, terminates May 1, 2023 and authorizes 10.6 million . The following table presents restricted stock and performance unit award activity for the nine months ended September 30, 2018: Restricted Stock Performance Units Shares Weighted Average Grant- Date Fair Value Shares Weighted Average Grant- Date Fair Value Outstanding at January 1, 2018 739,732 $ 77.23 226,558 $ 77.07 Granted 173,144 114.63 87,022 115.33 Vested (163,436 ) 67.28 (46,876 ) 74.46 Forfeitures (3,738 ) 81.04 — — Outstanding at September 30, 2018 745,702 $ 88.07 266,704 $ 90.01 Compensation Expense Our share-based compensation expense is recorded in "Selling, general, and administrative expenses." Compensation expense for share-based awards recognized in the Consolidated Statements of Income, net of forfeitures, was as follows (dollars in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Restricted stock $ 4.9 $ 3.8 $ 13.9 $ 11.3 Performance units 1.7 1.4 3.5 4.1 Total share-based compensation expense 6.6 5.2 17.4 15.4 Income tax benefit (1.6 ) (2.0 ) (4.4 ) (5.9 ) Share-based compensation expense, net of tax benefit $ 5.0 $ 3.2 $ 13.0 $ 9.5 The fair value of restricted stock is determined based on the closing price of the Company’s stock on the grant date. Compensation expense, net of estimated forfeitures, is recorded over the requisite service period. As PCA’s Board of Directors has the ability to accelerate the vesting of these awards upon an employee’s retirement, the Company accelerates the recognition of compensation expense for certain employees approaching normal retirement age. Performance unit awards are earned based on the achievement of defined performance rankings of Return on Invested Capital (ROIC) or Total Shareholder Return (TSR) compared to ROIC and TSR for peer companies. For performance unit awards made in 2018, 50% used TSR as the performance measure and 50% used ROIC as the performance measure. All units awarded before 2018 used ROIC as the performance measure. The ROIC component of performance unit awards are valued based on the closing price of the stock on the grant date. As the ROIC component contains a performance condition, compensation expense, net of estimated forfeitures, is recorded over the requisite service period based on the most probable number of awards expected to vest. The TSR component of performance unit awards is valued using a Monte Carlo simulation as the TSR component contains a market condition. The Monte Carlo simulation estimates the fair value of the TSR component based on the expected term of the award, a risk-free interest rate, expected dividends, and expected volatility of the Company’s common stock and the common stock of the peer companies. Compensation expense is recorded ratably over the expected term of the award. The unrecognized compensation expense for all share-based awards at September 30, 2018 was as follows (dollars in millions): September 30, 2018 Unrecognized Compensation Expense Remaining Weighted Average Recognition Period (in years) Restricted stock $ 36.5 2.5 Performance units 15.7 3.1 Total unrecognized share-based compensation expense $ 52.2 2.7

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Stockholders' Equity	1 5 . Stockholders' Equity Dividends During the nine months ended September 30, 2018, we paid $193.4 million of dividends to shareholders. On May 15, 2018, PCA announced an increase of its quarterly cash dividend on its common stock from an annual payout of $2.52 per share to $3.16 per share. On August 30, 2018, PCA’s Board of Directors declared a regular quarterly cash dividend of $0.79 per share of common stock, which was paid on October 15, 2018 to shareholders of record as of September 14, 2018. The dividend payment was $74.7 million. Repurchases of Common Stock On February 25, 2016, PCA announced that its Board of Directors authorized the repurchase of $200.0 million of the Company’s outstanding common stock. Repurchases may be made from time to time in open market or privately negotiated transactions in accordance with applicable securities regulations. The timing and amount of repurchases will be determined by the Company in its discretion based on factors such as PCA’s stock price and market and business conditions. The Company did not repurchase any shares of its common stock under this authority during the three and nine months ended September 30, 2018. At September 30, 2018, $193.0 million of the authorized amount remained available for repurchase of the Company’s common stock. Accumulated Other Comprehensive Income (Loss) Changes in accumulated other comprehensive income (loss) (AOCI) by component were as follows (dollars in millions). Amounts in parentheses indicate losses: Foreign Currency Translation Adjustments Unrealized Loss On Treasury Locks, Net Unrealized Loss on Foreign Exchange Contracts Unfunded Employee Benefit Obligations Total Balance at January 1, 2018 $ (0.3 ) $ (14.2 ) $ (0.3 ) $ (142.1 ) $ (156.9 ) Amounts reclassified from AOCI, net of tax (0.1 ) 3.0 — 8.9 11.8 Balance at September 30, 2018 $ (0.4 ) $ (11.2 ) $ (0.3 ) $ (133.2 ) $ (145.1 ) Reclassifications out of AOCI were as follows (dollars in millions). Amounts in parentheses indicate expenses in the Consolidated Statements of Income: Amounts Reclassified from AOCI Three Months Ended September 30, Nine Months Ended September 30, Details about AOCI Components 2018 2017 2018 2017 Unrealized loss on treasury locks, net (a) $ (1.3 ) $ (1.4 ) $ (4.0 ) $ (4.2 ) See (a) below 0.3 0.5 1.0 1.6 Tax benefit $ (1.0 ) $ (0.9 ) $ (3.0 ) $ (2.6 ) Net of tax Unfunded employee benefit obligations (b) Amortization of prior service costs $ (1.7 ) $ (1.3 ) $ (5.0 ) $ (4.3 ) See (b) below Amortization of actuarial gains / (losses) (2.3 ) (1.8 ) (6.9 ) (5.6 ) See (b) below (4.0 ) (3.1 ) (11.9 ) (9.9 ) Total before tax 1.0 1.2 3.0 3.7 Tax benefit $ (3.0 ) $ (1.9 ) $ (8.9 ) $ (6.2 ) Net of tax (a) This AOCI component is included in interest expense, net and other. Amount relates to the amortization of the effective portion of treasury lock derivative instruments recorded in AOCI. The net amount of settlement gains or losses on derivative instruments included in AOCI to be amortized over the next 12 months is a net loss of $5.2 million ($3.9 million after tax). For a discussion of treasury lock derivative instrument activity, see Note 13, Derivative Instruments and Hedging Activities, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2017 Annual Report on Form 10-K. (b) These AOCI components are included in the computation of net pension and postretirement benefit costs. See Note 13, Employee Benefit Plans and Other Postretirement Benefits, for additional information.

Concentrations of Risk

Concentrations of Risk	9 Months Ended
	Sep. 30, 2018
Risks And Uncertainties [Abstract]
Concentration of Risk	16 . Concentrations of Risk Our Paper segment has a long-standing commercial and contractual relationship with Office Depot, our largest customer in the paper business. This relationship exposes us to a significant concentration of business and financial risk. Our sales to Office Depot represent approximately 7% of our total Company sales revenue for both the nine month periods ended September 30, 2018 and 2017 and approximately For full year 2017, sales to Office Depot represented 43% of our Paper segment sales. If these sales are reduced, we would need to find new customers. We may not be able to fully replace any lost sales, and any new sales may be at lower prices or higher costs. Any significant deterioration in the financial condition of Office Depot affecting its ability to pay or any other change that affects its willingness to purchase our products will harm our business and results of operations.

Transactions With Related Parti

Transactions With Related Parties	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Transactions With Related Parties	17 . Transactions With Related Parties Louisiana Timber Procurement Company, L.L.C. (LTP) is a variable-interest entity that is 50% owned by PCA and 50% owned by Boise Cascade Company (Boise Cascade). LTP procures sawtimber, pulpwood, residual chips, and other residual wood fiber to meet the wood and fiber requirements of PCA and Boise Cascade in Louisiana. PCA is the primary beneficiary of LTP and has the power to direct the activities that most significantly affect the economic performance of LTP. Therefore, we consolidate 100% of LTP in our financial statements in our Corporate and Other segment. The carrying amounts of LTP's assets and liabilities (which relate primarily to non-inventory working capital items) on our Consolidated Balance Sheets were $3.5 million at September 30, 2018 and $3.0 million at December 31, 2017. During the three months ended September 30, 2018 and 2017, we recorded $22.4 million and $20.8 million, respectively, and during the nine months ended September 30, 2018 and 2017 we recorded $65.5 million and $66.0 million, respectively, of LTP sales to Boise Cascade in "Net Sales" in the Consolidated Statements of Income and approximately the same amount of expenses in "Cost of Sales". During the three months ended September 30, 2018 and 2017, fiber purchases from related parties were $4.1 million and $4.0 million ,

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Information	18 . Segment Information We report our business in three reportable segments: Packaging, Paper, and Corporate and Other. These segments represent distinct businesses that are managed separately because of differing products and services. Each of these businesses requires distinct operating and marketing strategies. During the second quarter of 2018, the Company discontinued the production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill and converted the No. 3 machine to a virgin kraft linerboard machine. Subsequent to the date of conversion in May 2018, operating results for the Wallula mill are primarily included in the Packaging segment. Each segment’s profits and losses are measured on operating profits before interest expense, net and income taxes. For certain allocated expenses, the related assets and liabilities remain in the Corporate and Other segment. Selected financial information by reportable segment was as follows (dollars in millions): Sales, net Three Months Ended September 30, 2018 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 1,528.3 $ 6.8 $ 1,535.1 $ 284.4 (b) Paper 254.3 — 254.3 32.3 (b) Corporate and other 27.3 32.3 59.6 (18.2 ) (b) Intersegment eliminations — (39.1 ) (39.1 ) — $ 1,809.9 $ — $ 1,809.9 298.5 Interest expense, net and other (24.4 ) Income before taxes $ 274.1 Sales, net Three Months Ended September 30, 2017 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 1,340.6 $ 6.0 $ 1,346.6 $ 263.2 (c) Paper 271.4 — 271.4 (2.6 ) (c) Corporate and Other 28.1 33.0 61.1 (18.0 ) Intersegment eliminations — (39.0 ) (39.0 ) — $ 1,640.1 $ — $ 1,640.1 242.6 Interest expense, net and other (25.7 ) Income before taxes $ 216.9 Sales, net Nine Months Ended September 30, 2018 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 4,414.7 $ 19.5 $ 4,434.2 $ 782.3 (b) Paper 774.5 — 774.5 55.7 (b) Corporate and Other 78.9 94.9 173.8 (57.0 ) (b) Intersegment eliminations — (114.4 ) (114.4 ) — $ 5,268.1 $ — $ 5,268.1 781.0 Interest expense, net and other (75.0 ) Income before taxes $ 706.0 Sales, net Nine Months Ended September 30, 2017 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 3,897.4 $ 17.6 $ 3,915.0 $ 681.7 (c)(d) Paper 784.3 — 784.3 52.5 (c) Corporate and Other 78.9 92.3 171.2 (54.1 ) (c)(d) Intersegment eliminations — (109.9 ) (109.9 ) — $ 4,760.6 $ — $ 4,760.6 680.1 Interest expense, net and other (75.5 ) Income before taxes $ 604.6 (a) Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, New and Recently Adopted Accounting Standards, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Three Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Three Months Ended September 30, 2017 Adjusted Packaging $ 261.5 $ 1.7 $ 263.2 Paper (0.7 ) (1.9 ) (2.6 ) Corporate (18.5 ) 0.5 (18.0 ) Income from operations 242.3 0.3 242.6 Interest expense, net and other (25.4 ) (0.3 ) (25.7 ) Income before taxes $ 216.9 $ — $ 216.9 Segment income (loss) Nine Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Nine Months Ended September 30, 2017 Adjusted Packaging $ 676.8 $ 4.9 $ 681.7 Paper 58.1 (5.6 ) 52.5 Corporate (55.7 ) 1.6 (54.1 ) Income from operations 679.2 0.9 680.1 Interest expense, net and other (74.6 ) (0.9 ) (75.5 ) Income before taxes $ 604.6 $ — $ 604.6 (b) The three and nine months ended September 30, 2018 include: 1. $4.0 million and $26.4 million, respectively, of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine. 2. $1.3 million and $1.8 million, respectively, of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility. 3. $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. 4. $0.1 million of charges related to the Sacramento Container acquisition and integration. (c) The three and nine months ended September 30, 2017 include: 1. $0.9 million and $1.9 million, respectively, of charges consisting of closure costs related to corrugated products facilities, a paper administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. 2. $0.5 million and $0.8 million, respectively, of charges related to the Sacramento Container Corporation acquisition and integration costs related to other recent acquisitions. 3. $25.3 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine . ( d ) The nine months ended September 30, 2017 include: 1. $5.0 million of costs for the property damage and business interruption insurance deductible corresponding to the February 2017 explosion at our DeRidder, Louisiana mill. 2 . $2.3 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

Commitments, Guarantees, Indemn

Commitments, Guarantees, Indemnifications and Legal Proceedings	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments, Guarantees, Indemnifications and Legal Proceedings	19 . Commitments, Guarantees, Indemnifications and Legal Proceedings We have financial commitments and obligations that arise in the ordinary course of our business. These include long-term debt, capital commitments, lease obligations, and purchase commitments for goods and services, and legal proceedings, all of which are discussed in Note 9, Debt, and Note 18, Commitments, Guarantees, Indemnifications, and Legal Proceedings, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2017 Annual Report on Form 10-K. Guarantees and Indemnifications We provide guarantees, indemnifications, and other assurances to third parties in the normal course of our business. These include tort indemnifications, product guarantees, environmental assurances, and representations and warranties in commercial agreements. At September 30, 2018, we are not aware of any material liabilities arising from any guarantee, indemnification, or financial assurance we have provided. If we determined such a liability was probable and subject to reasonable determination, we would accrue for it at that time. DeRidder Mill Incident On February 8, 2017, a tank located in the pulp mill at the Company's DeRidder, Louisiana facility exploded, resulting in three contractor fatalities and other injuries. The Company has been served with multiple lawsuits involving the decedents and other allegedly injured parties, alleging negligence on the part of the Company and claiming compensatory and punitive damages. The Company is vigorously defending these lawsuits. The Company believes that these suits are covered by its liability insurance policies, subject to an aggregate $1.0 million deductible. The incident remains under investigation and all lawsuits are in the early stages. Accordingly, the Company is unable to estimate a range of reasonable possible losses at this time. The Company has also incurred property damage and business interruption losses and has claimed these losses, subject to a $5.0 million deductible, under its property damage and business interruption insurance policy. As of December 31, 2017, the Company finalized the claim with the insurance carrier and received $17.0 million in insurance proceeds during the first quarter of 2018. The insurance proceeds are included in net cash provided by operating activities ($14.5 million) and in net cash used for investing activities ($2.5 million) based on the nature of the reimbursement. The Company has cooperated with investigations from the U.S. Occupational Health and Safety Administration (OSHA), the U.S. Chemical Safety Board (CSB) and the U.S. Environmental Protection Agency (EPA). The U.S. Chemical Safety Board completed its investigation and issued its report during the second quarter of 2018. The Company settled with OSHA during the second quarter of 2018 and paid approximately $40,000 in penalties for citations. The EPA investigation is ongoing. Legal Proceedings We are also a party to various legal actions arising in the ordinary course of our business. These legal actions include commercial liability claims, premises liability claims, and employment-related claims, among others. As of the date of this filing, we believe it is not reasonably possible that any of the legal actions against us will, either individually or in the aggregate, have a material adverse effect on our financial condition, results of operations, or cash flows.

Nature of Operations and Basi_2

Nature of Operations and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Reportable Segments	We report our business in three reportable segments: Packaging, Paper, and Corporate and Other. Our Packaging segment produces a wide variety of corrugated packaging products. The Paper segment manufactures and sells a range of communication-based papers. During the second quarter of 2018, the Company discontinued the production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill and converted the No. 3 machine to a virgin kraft linerboard machine. Subsequent to the date of conversion in May 2018, operating results for the Wallula mill are primarily included in the Packaging segment. Corporate and other includes support staff services and related assets and liabilities, transportation assets, and activity related to other ancillary support operations. For more information about our segments, see Note 18 Segment Information. In these consolidated financial statements, certain amounts in prior periods' consolidated financial statements have been reclassified to conform with the current period presentation.
Basis of Accounting and Presentation	The consolidated financial statements of PCA as of September 30, 2018 and for the three and nine months ended September 30, 2018 and 2017 are unaudited but include all adjustments (consisting only of normal recurring adjustments) that management considers necessary for a fair presentation of such financial statements. These financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with Article 10 of Regulation S-X of the Securities and Exchange Commission (SEC). Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete audited financial statements. Operating results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018. These consolidated financial statements should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2017.
Use of Estimates	The preparation of the consolidated financial statements involves the use of estimates and accruals. Actual results may vary from those estimates.
Consolidation	The consolidated financial statements include the accounts of PCA and its majority-owned subsidiaries after elimination of intercompany balances and transactions.
New and Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Standards Effective January 1, 2018, the Company adopted Accounting Standards Update (“ASU”) 2014-09 (Topic 606): Revenue from Contracts with Customers Revenue Recognition a. The Company ships a portion of its products to customers under consignment agreements. These products do not have an alternative use, and, under the new standard, revenue associated with these products is required to be recognized earlier than under prior revenue recognition standards. Utilizing the modified retrospective method, the cumulative impact of adopting the new standard resulted in an increase of approximately $1.6 million, net of tax, to opening retained earnings as of January 1, 2018. b. The new revenue standard also provides additional clarity concerning contract fulfillment costs, which resulted in certain costs being classified as cost of sales rather than selling, general and administrative expenses beginning January 1, 2018. For the three and nine months ended September 30, 2018, this amount totaled $6.9 million and $20.0 million, respectively. See Note 3, Revenue, for more information. Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. are required to be presented in the income statement separately from the service cost component and outside the subtotal of operating income. The update also allows only the service cost component to be eligible for capitalization for internally developed capital projects. The amendments in this update are applied retrospectively for the income statement presentations and prospectively for the capitalization of service costs. The adoption of this ASU retrospectively resulted in a $0.3 million and $0.9 million reclassification between cost of sales and selling, general and administrative expenses (both components of income from operations) and interest expense, net and other (a component outside of income from operations) for the three and nine months ended September 30, 2017, respectively. Effective January 1, 2018, the Company adopted ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , which clarifies what changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. T Effective January 1, 2018, the Company adopted Clarifying the Definition of a Business Effective January 1, 2018, the Company adopted Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments
New Accounting Standards Not Yet Adopted	New Accounting Standards Not Yet Adopted In August 2018, the issued ASU 2018-14, Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans . ASU 2018-14 removes certain disclosures that are not considered cost beneficial, clarifies certain required disclosures and adds additional disclosures. The ASU is effective for annual periods beginning after December 31, 2020, with early adoption permitted. The amendments in ASU 2018-14 would need to be applied on a retrospective basis. The Company is currently evaluating the impact this guidance will have on its related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. The Company is currently evaluating the impact of the new guidance. In February 2018, the FASB issued ASU 2018-02 (Topic 220): Income Statement – R eporting Comprehensive Income – Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which allows for optional reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects resulting from the enactment of H.R.1 (P.L. 115-97), originally known as the “Tax Cuts and Jobs Act,” in December 2017. An entity that elects to reclassify these amounts must reclassify stranded tax effects related to the change in federal tax rate for all items accounted for in other comprehensive income (e.g., pension and postretirement benefits and cash flow hedges). Entities may also elect to reclassify other stranded tax effects that relate to the Act but do not directly relate to the change in the federal tax rate (e.g., state taxes). Upon adoption of ASU 2018-02, entities are required to disclose their policy for releasing the income tax effects from accumulated other comprehensive income. ASU 2018-02 is effective for annual periods beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect this ASU to have a material impact on the Company’s financial position, results of operations, or cash flow. In February 2016, the FASB issued ASU 2016-02 (Topic 842): Leases Codification Improvements to Topic 842, Leases Leases (Topic 842): Targeted Improvements ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and early adoption is permitted. We are in the process of implementing changes to our systems and processes in conjunction with our review of existing lease agreements, which primarily consist of equipment and real estate leases. In addition, we are currently working with a vendor to implement a technology tool to assist with the accounting and reporting requirements of the new standard. We will adopt Topic 842 effective January 1, 2019 and expect to elect certain available transitional practical expedients. We are still in the process of determining the effects on our financial statements but do expect to recognize a liability and corresponding asset associated with in-scope operating leases. There were no other accounting standards recently issued that had or are expected to have a material impact on our financial position or results of operations.
Revenue Recognition	Revenue Recognition Revenue is recognized when control of the promised goods or services is transferred to customers in an amount that reflects the consideration expected to be entitled in exchange for those goods or services. Sales, value added, and other taxes collected concurrently with revenue-producing activities are excluded from revenue. The following table presents our revenues disaggregated by product line (dollars in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 (a) 2018 2017 (a) Packaging $ 1,535.1 $ 1,346.6 $ 4,434.2 $ 3,915.0 Paper 254.3 271.4 774.5 784.3 Corporate and other 20.5 22.1 59.4 61.3 Total revenue $ 1,809.9 $ 1,640.1 $ 5,268.1 $ 4,760.6 (a) Prior periods have not been adjusted under the modified retrospective method for Topic 606.
Inventory Valuation	We value our raw materials, work in process, and finished goods inventories using lower of cost, as determined by the average cost method, or market. Supplies and materials are valued at the first-in, first-out (FIFO) or average cost methods.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue From Contract With Customer [Abstract]
Summary of Revenues Disaggregated by Product Line	The following table presents our revenues disaggregated by product line (dollars in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 (a) 2018 2017 (a) Packaging $ 1,535.1 $ 1,346.6 $ 4,434.2 $ 3,915.0 Paper 254.3 271.4 774.5 784.3 Corporate and other 20.5 22.1 59.4 61.3 Total revenue $ 1,809.9 $ 1,640.1 $ 5,268.1 $ 4,760.6 (a) Prior periods have not been adjusted under the modified retrospective method for Topic 606.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The total purchase price has been allocated to tangible and intangible assets acquired and liabilities assumed based on respective fair values, as follows (dollars in millions): 12/31/2017 Allocation Adjustments Revised Allocation Goodwill $ 151.1 $ 5.5 $ 156.6 Other intangible assets 72.6 (5.5 ) 67.1 Property, plant and equipment 26.7 — 26.7 Other net assets 23.4 — 23.4 Net assets acquired $ 273.8 $ — $ 273.8

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Income Per Common Share	The following table sets forth the computation of basic and diluted income per common share for the periods presented (dollars and shares in millions, except per share data): Three Months Ended Nine Months Ended September 30, September 30, Numerator: 2018 2017 2018 2017 Net income $ 206.7 $ 139.1 $ 533.4 $ 399.7 Less: distributed and undistributed earnings allocated to participating securities (1.6 ) (1.1 ) (4.1 ) (3.4 ) Net income attributable to common shareholders $ 205.1 $ 138.0 $ 529.3 $ 396.3 Denominator: Weighted average basic common shares outstanding 93.7 93.6 93.7 93.5 Effect of dilutive securities 0.3 0.2 0.2 0.2 Weighted average diluted common shares outstanding 94.0 93.8 93.9 93.7 Basic income per common share $ 2.19 $ 1.47 $ 5.65 $ 4.24 Diluted income per common share $ 2.18 $ 1.47 $ 5.64 $ 4.23

Other Income (Expense), Net (Ta

Other Income (Expense), Net (Tables)	9 Months Ended
	Sep. 30, 2018
Other Income And Expenses [Abstract]
Components of Other Income (Expense), Net	The components of other income (expense), net, were as follows (dollars in millions): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Asset disposals and write-offs $ (5.1 ) $ (3.9 ) $ (14.4 ) $ (8.6 ) Wallula mill restructuring (a) (3.7 ) (22.7 ) (11.6 ) (22.7 ) Facilities closure and other costs (b) (1.5 ) (0.9 ) (1.6 ) (1.9 ) Acquisition and integration related costs (c) (0.1 ) (0.5 ) (0.1 ) (0.8 ) Insurance deductible for property damage (d) (0.5 ) — (0.5 ) — DeRidder mill incident (e) — 2.6 — 0.1 Hexacomb working capital adjustment (f) — — — 2.3 Other 0.4 0.6 (4.0 ) (0.8 ) Total $ (10.5 ) $ (24.8 ) $ (32.2 ) $ (32.4 ) (a) Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine. (b) For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes charges consisting of closure costs related to corrugated products facilities and a paper administration facility and costs related to a lump sum settlement payment of a multiemployer pension plan for one of our corrugated products facilities. (c) Includes charges related to recent acquisitions and the integration of recent acquisitions. (d) For 2018, includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities. (e) Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill. (f) Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Components of Inventories	The components of inventories were as follows (dollars in millions): September 30, December 31, 2018 2017 Raw materials $ 317.9 $ 279.8 Work in process 14.9 12.6 Finished goods 180.4 217.0 Supplies and materials 267.4 253.1 Inventories $ 780.6 $ 762.5

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	9 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Components of Property, Plant, and Equipment	The components of property, plant, and equipment were as follows (dollars in millions): September 30, December 31, 2018 2017 Land and land improvements $ 162.0 $ 156.0 Buildings 756.2 729.8 Machinery and equipment 5,356.7 5,162.5 Construction in progress 240.6 194.5 Other 72.8 68.4 Property, plant and equipment, at cost 6,588.3 6,311.2 Less accumulated depreciation (3,523.2 ) (3,386.3 ) Property, plant, and equipment, net $ 3,065.1 $ 2,924.9

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	Changes in the carrying amount of our goodwill are as follows (dollars in millions): Goodwill Balance at January 1, 2018 $ 883.2 Acquisitions (a) 5.5 Balance at September 30, 2018 $ 888.7 (a) During the nine months ended September 30, 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container.
Components of Intangible Assets	The weighted average remaining useful life, gross carrying amount, and accumulated amortization of our intangible assets were as follows (dollars in millions): September 30, 2018 December 31, 2017 Weighted Average Remaining Useful Life (in Years) Gross Carrying Amount Accumulated Amortization Weighted Average Remaining Useful Life (in Years) Gross Carrying Amount Accumulated Amortization Customer relationships (a) 11.2 $ 491.4 $ 135.5 11.8 $ 497.8 $ 109.8 Trademarks and trade names (a) 10.4 33.9 17.6 9.8 32.9 13.2 Other (a) 3.1 4.3 2.6 3.6 4.3 2.0 Total intangible assets (excluding goodwill) 11.1 $ 529.6 $ 155.7 11.7 $ 535.0 $ 125.0 (a) In connection with the October 2017 acquisition of Sacramento Container, the Company recorded intangible assets of $68.4 million for customer relationships, $4.1 million for trade names, and $0.1 million for other intangibles. During the second quarter ended June 30, 2018, the Company made a $5.5 million net adjustment based on the final valuation received for the intangible assets. This adjustment resulted in a revision to the original allocations for customer relationships and trade names. As of June 30, 2018, the revised allocations for customer relationships and trade names were $61.9 million and $5.1 million, respectively.

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Accrued Liabilities Current And Noncurrent [Abstract]
Components of Accrued Liabilities	The components of accrued liabilities were as follows (dollars in millions): September 30, December 31, 2018 2017 Compensation and benefits $ 131.1 $ 127.5 Medical insurance and workers’ compensation 27.0 23.9 Customer volume discounts and rebates 21.5 23.4 Franchise, property, sales and use taxes 21.3 16.0 Environmental liabilities and asset retirement obligations 4.7 4.0 Severance, retention, and relocation 3.3 3.1 Other 14.5 5.3 Total $ 223.4 $ 203.2

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Summary of Debt	At September 30, 2018 and December 31, 2017, our long-term debt and interest rates on that debt were as follows (dollars in millions): September 30, 2018 December 31, 2017 Amount Interest Rate Amount Interest Rate 6.50% Senior Notes due March 2018 $ — — % $ 150.0 6.50 % 2.45% Senior Notes, net of discount of $0.4 million and $0.5 million as of September 30, 2018 and December 31, 2017, respectively, due December 2020 499.6 2.45 % 499.5 2.45 % 3.90% Senior Notes, net of discount of $0.1 million and $0.2 million as of September 30, 2018 and December 31, 2017, respectively, due June 2022 399.9 3.90 % 399.8 3.90 % 4.50% Senior Notes, net of discount of $1.1 million and $1.2 million as of September 30, 2018 and December 31, 2017, respectively, due November 2023 698.9 4.50 % 698.8 4.50 % 3.65% Senior Notes, net of discount of $0.7 million and $0.8 million as of September 30, 2018 and December 31, 2017, respectively, due September 2024 399.3 3.65 % 399.2 3.65 % 3.40% Senior Notes, net of discount of $1.5 million and $1.6 million as of September 30, 2018 and December 31, 2017, respectively, due December 2027 498.5 3.40 % 498.4 3.40 % Total 2,496.2 3.64 % 2,645.7 3.80 % Less current portion — — % 150.0 6.50 % Less unamortized debt issuance costs 13.3 15.3 Total long-term debt $ 2,482.9 3.64 % $ 2,480.4 3.64 %

Employee Benefit Plans and Ot_2

Employee Benefit Plans and Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Costs	The components of net periodic benefit cost for our pension plans were as follows (dollars in millions): Pension Plans Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Service cost $ 6.3 $ 5.8 $ 18.8 $ 18.0 Interest cost 10.6 10.4 31.8 31.1 Expected return on plan assets (14.2 ) (13.5 ) (42.5 ) (40.5 ) Net amortization of unrecognized amounts Prior service cost 1.8 1.4 5.2 4.4 Actuarial loss 2.3 1.9 7.0 5.7 Net periodic benefit cost $ 6.8 $ 6.0 $ 20.3 $ 18.7 The components of net periodic benefit cost for our postretirement plans were as follows (dollars in millions): Postretirement Plans Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Service cost $ 0.1 $ 0.1 $ 0.2 $ 0.2 Interest cost 0.1 0.2 0.4 0.5 Net amortization of unrecognized amounts Prior service cost (0.1 ) (0.1 ) (0.2 ) (0.1 ) Actuarial income — (0.1 ) (0.1 ) (0.1 ) Net periodic benefit cost $ 0.1 $ 0.1 $ 0.3 $ 0.5

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Share Based Compensation [Abstract]
Summary of Restricted Stock and Performance Unit Award Activity	The following table presents restricted stock and performance unit award activity for the nine months ended September 30, 2018: Restricted Stock Performance Units Shares Weighted Average Grant- Date Fair Value Shares Weighted Average Grant- Date Fair Value Outstanding at January 1, 2018 739,732 $ 77.23 226,558 $ 77.07 Granted 173,144 114.63 87,022 115.33 Vested (163,436 ) 67.28 (46,876 ) 74.46 Forfeitures (3,738 ) 81.04 — — Outstanding at September 30, 2018 745,702 $ 88.07 266,704 $ 90.01
Compensation Expense For Restricted Stock and Performance Units	Our share-based compensation expense is recorded in "Selling, general, and administrative expenses." Compensation expense for share-based awards recognized in the Consolidated Statements of Income, net of forfeitures, was as follows (dollars in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Restricted stock $ 4.9 $ 3.8 $ 13.9 $ 11.3 Performance units 1.7 1.4 3.5 4.1 Total share-based compensation expense 6.6 5.2 17.4 15.4 Income tax benefit (1.6 ) (2.0 ) (4.4 ) (5.9 ) Share-based compensation expense, net of tax benefit $ 5.0 $ 3.2 $ 13.0 $ 9.5
Unrecognized Compensation For Restricted Stock and Performance Units	The unrecognized compensation expense for all share-based awards at September 30, 2018 was as follows (dollars in millions): September 30, 2018 Unrecognized Compensation Expense Remaining Weighted Average Recognition Period (in years) Restricted stock $ 36.5 2.5 Performance units 15.7 3.1 Total unrecognized share-based compensation expense $ 52.2 2.7

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Components of Changes in Accumulated Other Comprehensive Income (AOCI)	Changes in accumulated other comprehensive income (loss) (AOCI) by component were as follows (dollars in millions). Amounts in parentheses indicate losses: Foreign Currency Translation Adjustments Unrealized Loss On Treasury Locks, Net Unrealized Loss on Foreign Exchange Contracts Unfunded Employee Benefit Obligations Total Balance at January 1, 2018 $ (0.3 ) $ (14.2 ) $ (0.3 ) $ (142.1 ) $ (156.9 ) Amounts reclassified from AOCI, net of tax (0.1 ) 3.0 — 8.9 11.8 Balance at September 30, 2018 $ (0.4 ) $ (11.2 ) $ (0.3 ) $ (133.2 ) $ (145.1 )
Reclassifications Out of Accumulated Other Comprehensive Income (AOCI)	Reclassifications out of AOCI were as follows (dollars in millions). Amounts in parentheses indicate expenses in the Consolidated Statements of Income: Amounts Reclassified from AOCI Three Months Ended September 30, Nine Months Ended September 30, Details about AOCI Components 2018 2017 2018 2017 Unrealized loss on treasury locks, net (a) $ (1.3 ) $ (1.4 ) $ (4.0 ) $ (4.2 ) See (a) below 0.3 0.5 1.0 1.6 Tax benefit $ (1.0 ) $ (0.9 ) $ (3.0 ) $ (2.6 ) Net of tax Unfunded employee benefit obligations (b) Amortization of prior service costs $ (1.7 ) $ (1.3 ) $ (5.0 ) $ (4.3 ) See (b) below Amortization of actuarial gains / (losses) (2.3 ) (1.8 ) (6.9 ) (5.6 ) See (b) below (4.0 ) (3.1 ) (11.9 ) (9.9 ) Total before tax 1.0 1.2 3.0 3.7 Tax benefit $ (3.0 ) $ (1.9 ) $ (8.9 ) $ (6.2 ) Net of tax (a) This AOCI component is included in interest expense, net and other. Amount relates to the amortization of the effective portion of treasury lock derivative instruments recorded in AOCI. The net amount of settlement gains or losses on derivative instruments included in AOCI to be amortized over the next 12 months is a net loss of $5.2 million ($3.9 million after tax). For a discussion of treasury lock derivative instrument activity, see Note 13, Derivative Instruments and Hedging Activities, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2017 Annual Report on Form 10-K. (b) These AOCI components are included in the computation of net pension and postretirement benefit costs. See Note 13, Employee Benefit Plans and Other Postretirement Benefits, for additional information.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Selected Financial Information by Reportable Segment	Selected financial information by reportable segment was as follows (dollars in millions): Sales, net Three Months Ended September 30, 2018 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 1,528.3 $ 6.8 $ 1,535.1 $ 284.4 (b) Paper 254.3 — 254.3 32.3 (b) Corporate and other 27.3 32.3 59.6 (18.2 ) (b) Intersegment eliminations — (39.1 ) (39.1 ) — $ 1,809.9 $ — $ 1,809.9 298.5 Interest expense, net and other (24.4 ) Income before taxes $ 274.1 Sales, net Three Months Ended September 30, 2017 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 1,340.6 $ 6.0 $ 1,346.6 $ 263.2 (c) Paper 271.4 — 271.4 (2.6 ) (c) Corporate and Other 28.1 33.0 61.1 (18.0 ) Intersegment eliminations — (39.0 ) (39.0 ) — $ 1,640.1 $ — $ 1,640.1 242.6 Interest expense, net and other (25.7 ) Income before taxes $ 216.9 Sales, net Nine Months Ended September 30, 2018 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 4,414.7 $ 19.5 $ 4,434.2 $ 782.3 (b) Paper 774.5 — 774.5 55.7 (b) Corporate and Other 78.9 94.9 173.8 (57.0 ) (b) Intersegment eliminations — (114.4 ) (114.4 ) — $ 5,268.1 $ — $ 5,268.1 781.0 Interest expense, net and other (75.0 ) Income before taxes $ 706.0 Sales, net Nine Months Ended September 30, 2017 Trade Intersegment Total Operating Income (Loss) (a) Packaging $ 3,897.4 $ 17.6 $ 3,915.0 $ 681.7 (c)(d) Paper 784.3 — 784.3 52.5 (c) Corporate and Other 78.9 92.3 171.2 (54.1 ) (c)(d) Intersegment eliminations — (109.9 ) (109.9 ) — $ 4,760.6 $ — $ 4,760.6 680.1 Interest expense, net and other (75.5 ) Income before taxes $ 604.6 (a) Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, New and Recently Adopted Accounting Standards, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Three Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Three Months Ended September 30, 2017 Adjusted Packaging $ 261.5 $ 1.7 $ 263.2 Paper (0.7 ) (1.9 ) (2.6 ) Corporate (18.5 ) 0.5 (18.0 ) Income from operations 242.3 0.3 242.6 Interest expense, net and other (25.4 ) (0.3 ) (25.7 ) Income before taxes $ 216.9 $ — $ 216.9 Segment income (loss) Nine Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Nine Months Ended September 30, 2017 Adjusted Packaging $ 676.8 $ 4.9 $ 681.7 Paper 58.1 (5.6 ) 52.5 Corporate (55.7 ) 1.6 (54.1 ) Income from operations 679.2 0.9 680.1 Interest expense, net and other (74.6 ) (0.9 ) (75.5 ) Income before taxes $ 604.6 $ — $ 604.6 (b) The three and nine months ended September 30, 2018 include: 1. $4.0 million and $26.4 million, respectively, of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine. 2. $1.3 million and $1.8 million, respectively, of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility. 3. $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. 4. $0.1 million of charges related to the Sacramento Container acquisition and integration. (c) The three and nine months ended September 30, 2017 include: 1. $0.9 million and $1.9 million, respectively, of charges consisting of closure costs related to corrugated products facilities, a paper administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. 2. $0.5 million and $0.8 million, respectively, of charges related to the Sacramento Container Corporation acquisition and integration costs related to other recent acquisitions. 3. $25.3 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine . ( d ) The nine months ended September 30, 2017 include: 1. $5.0 million of costs for the property damage and business interruption insurance deductible corresponding to the February 2017 explosion at our DeRidder, Louisiana mill. 2 . $2.3 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

Nature of Operations and Basi_3

Nature of Operations and Basis of Presentation - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018Segment
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Date of incorporation	Jan. 25, 1999
Number of reportable segments	3

New and Recently Adopted Acco_2

New and Recently Adopted Accounting Standards - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Retained earnings	$ 2,185.5		$ 2,185.5			$ 1,867.4
Cost of sales	1,366.7	$ 1,243.1	4,048.2	$ 3,661.2
ASU 2014-09 | Difference between Revenue Guidance in Effect before and after Topic 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Retained earnings					$ 1.6
Cost of sales	$ 6.9		$ 20
ASU 2017-07
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification of components of income from operation and interest expense, net and other		$ 0.3		$ 0.9

Revenue - Summary of Revenues D

Revenue - Summary of Revenues Disaggregated by Product Line (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	[1]	Sep. 30, 2018	Sep. 30, 2017	[1]
Disaggregation Of Revenue [Line Items]
Revenue	$ 1,809.9	$ 1,640.1		$ 5,268.1	$ 4,760.6
Packaging
Disaggregation Of Revenue [Line Items]
Revenue	1,535.1	1,346.6		4,434.2	3,915
Paper
Disaggregation Of Revenue [Line Items]
Revenue	254.3	271.4		774.5	784.3
Corporate and Other
Disaggregation Of Revenue [Line Items]
Revenue	$ 20.5	$ 22.1		$ 59.4	$ 61.3
[1]	Prior periods have not been adjusted under the modified retrospective method for Topic 606.

Revenue - Additional Informatio

Revenue - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018
Packaging Corporation of America
Revenue [Line Items]
Variable interest entity, ownership percentage	50.00%
Boise Cascade Co-Owner of LTP
Revenue [Line Items]
Variable interest entity, ownership percentage	50.00%

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details) - USD ($) $ in Millions	Oct. 02, 2017	Jun. 30, 2018	Sep. 30, 2018
Sacramento Container Corporation
Business Acquisition [Line Items]
Acquisition completion date	Oct. 2, 2017
Cash purchase price	$ 274
Adjustment to final valuation of intangible assets		$ 5.5	$ 5.5
Decrease in other intangible assets with an offset to goodwill		$ (5.5)	$ (5.5)
Acquired finite-lived intangible assets, weighted average useful life	9 years 7 months 6 days
Sacramento Container Corporation | Minimum
Business Acquisition [Line Items]
Property, plant and equipment useful life	1 year
Sacramento Container Corporation | Maximum
Business Acquisition [Line Items]
Property, plant and equipment useful life	13 years
Northern Sheets LLC And Central California Sheets LLC
Business Acquisition [Line Items]
Percentage of membership interests acquired	100.00%

Acquisitions - Schedule of Acqu

Acquisitions - Schedule of Acquisitions (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 888.7	$ 883.2
Packaging
Business Acquisition [Line Items]
Goodwill		833.5	828
Sacramento Container Corporation
Business Acquisition [Line Items]
Other intangible assets		67.1	72.6
Property, plant and equipment		26.7	26.7
Other net assets		23.4	23.4
Net assets acquired		273.8	273.8
Goodwill, Adjustments		5.5
Other intangible assets, Adjustments	$ (5.5)	(5.5)
Sacramento Container Corporation | Packaging
Business Acquisition [Line Items]
Goodwill		$ 156.6	$ 151.1

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income	$ 206.7	$ 139.1	$ 533.4	$ 399.7
Less: distributed and undistributed earnings allocated to participating securities	(1.6)	(1.1)	(4.1)	(3.4)
Net income attributable to common shareholders	$ 205.1	$ 138	$ 529.3	$ 396.3
Denominator:
Weighted average basic common shares outstanding (in shares)	93.7	93.6	93.7	93.5
Effect of dilutive securities (in shares)	0.3	0.2	0.2	0.2
Weighted average diluted common shares outstanding (in shares)	94	93.8	93.9	93.7
Basic income per common share (in dollars per share)	$ 2.19	$ 1.47	$ 5.65	$ 4.24
Diluted income per common share (in dollars per share)	$ 2.18	$ 1.47	$ 5.64	$ 4.23

Other Income (Expense), Net - C

Other Income (Expense), Net - Components of Other Income (Expense), Net (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs		$ (5.1)	$ (3.9)	$ (14.4)	$ (8.6)
Facilities closure and other costs	[1]	(1.5)	(0.9)	(1.6)	(1.9)
Acquisition and integration related costs	[2]	(0.1)	(0.5)	(0.1)	(0.8)
Insurance deductible for property damage	[3]	(0.5)		(0.5)
Hexacomb working capital adjustment	[4]				2.3
Other		0.4	0.6	(4)	(0.8)
Total		(10.5)	(24.8)	(32.2)	(32.4)
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[5]	$ (3.7)	(22.7)	$ (11.6)	(22.7)
Deridder Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
DeRidder mill incident	[6]		$ 2.6		$ 0.1
[1]	For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes charges consisting of closure costs related to corrugated products facilities and a paper administration facility and costs related to a lump sum settlement payment of a multiemployer pension plan for one of our corrugated products facilities.
[2]	Includes charges related to recent acquisitions and the integration of recent acquisitions.
[3]	For 2018, includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities.
[4]	Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.
[5]	Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine.
[6]	Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill.

Other Income (Expense), Net -_2

Other Income (Expense), Net - Components of Other Income (Expense), Net (Parenthetical) (Details)	3 Months Ended
	Jun. 30, 2018
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
High-performance of virgin kraft linerboard machine percentage	100.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate, at federal statutory income tax rate, percent			21.00%		35.00%
Maximum measurement period to finalize accounting of tax			1 year
Income tax provision	$ 67.4	$ 77.8	$ 172.6	$ 204.9
Effective income tax rate, percent	24.60%	35.90%	24.40%	33.90%
Tax cuts and jobs act of 2017, reduction in federal tax rate, percent	14.00%		14.00%
Effective income tax rate, offset by domestic production activities, percent	3.20%		3.20%
Effective income tax rate, federal benefit of state tax deductions, percent	0.80%		0.80%
Cash paid for taxes, net of refunds received			$ 73.2	$ 208.3

Inventories - Components of Inv

Inventories - Components of Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 317.9	$ 279.8
Work in process	14.9	12.6
Finished goods	180.4	217
Supplies and materials	267.4	253.1
Inventories	$ 780.6	$ 762.5

Property, Plant, and Equipmen_2

Property, Plant, and Equipment - Components of Property, Plant, and Equipment (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Property, Plant, And Equipment [Line Items]
Property, plant and equipment, at cost	$ 6,588.3	$ 6,311.2
Less accumulated depreciation	(3,523.2)	(3,386.3)
Property, plant, and equipment, net	3,065.1	2,924.9
Land and Land Improvements
Property, Plant, And Equipment [Line Items]
Property, plant and equipment, at cost	162	156
Buildings
Property, Plant, And Equipment [Line Items]
Property, plant and equipment, at cost	756.2	729.8
Machinery and Equipment
Property, Plant, And Equipment [Line Items]
Property, plant and equipment, at cost	5,356.7	5,162.5
Construction in Progress
Property, Plant, And Equipment [Line Items]
Property, plant and equipment, at cost	240.6	194.5
Other
Property, Plant, And Equipment [Line Items]
Property, plant and equipment, at cost	$ 72.8	$ 68.4

Property, Plant, and Equipmen_3

Property, Plant, and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Depreciation [Abstract]
Depreciation expense	$ 89	$ 87	$ 275.3	$ 253
Incremental depreciation			14
Purchases of property, plant, and equipment included in accounts payable			$ 46.2		$ 29.8

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets -Goodwill - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 888.7	$ 883.2
Packaging
Goodwill [Line Items]
Goodwill	833.5	828
Paper
Goodwill [Line Items]
Goodwill	$ 55.2	$ 55.2

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2018	Sep. 30, 2018
Goodwill [Line Items]
Balance at January 1, 2018		$ 883.2
Balance at September 30, 2018		888.7
Sacramento Container Corporation
Goodwill [Line Items]
Acquisitions	$ 5.5	$ 5.5

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2018	Sep. 30, 2018
Sacramento Container Corporation
Goodwill [Line Items]
Increase to goodwill, acquisition adjustment	$ 5.5	$ 5.5

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	11 years 1 month 6 days	11 years 8 months 12 days
Gross Carrying Amount	$ 529.6	$ 535
Accumulated Amortization	$ 155.7	$ 125
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	11 years 2 months 12 days	11 years 9 months 18 days
Gross Carrying Amount	$ 491.4	$ 497.8
Accumulated Amortization	$ 135.5	$ 109.8
Trademarks and Trade Names
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	10 years 4 months 24 days	9 years 9 months 18 days
Gross Carrying Amount	$ 33.9	$ 32.9
Accumulated Amortization	$ 17.6	$ 13.2
Other Intangible Assets
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	3 years 1 month 6 days	3 years 7 months 6 days
Gross Carrying Amount	$ 4.3	$ 4.3
Accumulated Amortization	$ 2.6	$ 2

Goodwill and Intangible Asset_6

Goodwill and Intangible Assets - Intangible Assets (Parenthetical) (Details) - Sacramento Container Corporation - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2017	Oct. 31, 2017
Finite Lived Intangible Assets [Line Items]
Other intangible assets		$ 67.1	$ 72.6
Decrease in other intangible assets with an offset to goodwill	$ (5.5)	$ (5.5)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Other intangible assets	61.9			$ 68.4
Trademarks and Trade Names
Finite Lived Intangible Assets [Line Items]
Other intangible assets	$ 5.1			4.1
Other Intangible Assets
Finite Lived Intangible Assets [Line Items]
Other intangible assets				$ 0.1

Goodwill and Intangible Asset_7

Goodwill and Intangible Assets - Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible assets amortization expense	$ 10.2	$ 8.4	$ 30.7	$ 25.3

Accrued Liabilities - Component

Accrued Liabilities - Components of Accrued Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accrued Liabilities Current [Abstract]
Compensation and benefits	$ 131.1	$ 127.5
Medical insurance and workers’ compensation	27	23.9
Customer volume discounts and rebates	21.5	23.4
Franchise, property, sales and use taxes	21.3	16
Environmental liabilities and asset retirement obligations	4.7	4
Severance, retention, and relocation	3.3	3.1
Other	14.5	5.3
Total	$ 223.4	$ 203.2

Debt - Summary of Debt (Details

Debt - Summary of Debt (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt	$ 2,496.2	$ 2,645.7
Less current portion	0	150
Less unamortized debt issuance costs	13.3	15.3
Long-term debt	$ 2,482.9	$ 2,480.4
Weighted-average interest rate	3.64%	3.80%
6.50% Senior Notes due March 2018 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 150
Stated interest rate		6.50%
2.45% Senior Notes, due December 2020 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 499.6	$ 499.5
Stated interest rate	2.45%	2.45%
3.90% Senior Notes, due June 2022 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 399.9	$ 399.8
Stated interest rate	3.90%	3.90%
4.50% Senior Notes, due November 2023 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 698.9	$ 698.8
Stated interest rate	4.50%	4.50%
3.65% Senior Notes, due September 2024 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 399.3	$ 399.2
Stated interest rate	3.65%	3.65%
3.40% Senior Notes, due December 2027 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 498.5	$ 498.4
Stated interest rate	3.40%	3.40%
Current Portion of Long-term Debt
Debt Instrument [Line Items]
Weighted-average interest rate	0.00%	6.50%
Long-term Debt, Excluding Current Portion
Debt Instrument [Line Items]
Weighted-average interest rate	3.64%	3.64%

Debt - Summary of Debt (Parenth

Debt - Summary of Debt (Parenthetical) (Details) - Senior Notes - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
6.50% Senior Notes due March 2018
Debt Instrument [Line Items]
Stated interest rate		6.50%
Debt instrument, maturity date		Mar. 15, 2018
2.45% Senior Notes, due December 2020
Debt Instrument [Line Items]
Stated interest rate	2.45%	2.45%
Debt instrument, maturity date	Dec. 15, 2020	Dec. 15, 2020
Senior notes, discount	$ 0.4	$ 0.5
3.90% Senior Notes, due June 2022
Debt Instrument [Line Items]
Stated interest rate	3.90%	3.90%
Debt instrument, maturity date	Jun. 15, 2022	Jun. 15, 2022
Senior notes, discount	$ 0.1	$ 0.2
4.50% Senior Notes, due November 2023
Debt Instrument [Line Items]
Stated interest rate	4.50%	4.50%
Debt instrument, maturity date	Nov. 1, 2023	Nov. 1, 2023
Senior notes, discount	$ 1.1	$ 1.2
3.65% Senior Notes, due September 2024
Debt Instrument [Line Items]
Stated interest rate	3.65%	3.65%
Debt instrument, maturity date	Sep. 15, 2024	Sep. 15, 2024
Senior notes, discount	$ 0.7	$ 0.8
3.40% Senior Notes, due December 2027
Debt Instrument [Line Items]
Stated interest rate	3.40%	3.40%
Debt instrument, maturity date	Dec. 15, 2027	Dec. 15, 2027
Senior notes, discount	$ 1.5	$ 1.6

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Cash payments paid for interest			$ 58.6	$ 67.2
Amortization of treasury lock settlements	$ 1.3	$ 1.4	4	4.2
Amortization of financing costs	0.7	$ 0.5	2	$ 1.5
6.50% Senior Notes due March 2018
Debt Instrument [Line Items]
Repayment of debt			150
Fixed-Rate Senior Notes | Senior Notes
Debt Instrument [Line Items]
Book value of fixed rate debt	2,496.2		2,496.2
Long-term debt (fixed-rate debt), fair value	$ 2,478		$ 2,478

Employee Benefit Plans and Ot_3

Employee Benefit Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6.3	$ 5.8	$ 18.8	$ 18
Interest cost	10.6	10.4	31.8	31.1
Expected return on plan assets	(14.2)	(13.5)	(42.5)	(40.5)
Net amortization of unrecognized amounts, Prior service cost	1.8	1.4	5.2	4.4
Net amortization of unrecognized amounts, Actuarial loss (income)	2.3	1.9	7	5.7
Net periodic benefit cost	6.8	6	20.3	18.7
Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.1	0.1	0.2	0.2
Interest cost	0.1	0.2	0.4	0.5
Net amortization of unrecognized amounts, Prior service cost	(0.1)	(0.1)	(0.2)	(0.1)
Net amortization of unrecognized amounts, Actuarial loss (income)		(0.1)	(0.1)	(0.1)
Net periodic benefit cost	$ 0.1	$ 0.1	$ 0.3	$ 0.5

Employee Benefit Plans and Ot_4

Employee Benefit Plans and Other Postretirement Benefits - Additional Information (Details) - Qualified Plan - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Contributions [Abstract]
Minimum pension contributions			$ 4.6
Pension Plans
Pension Contributions [Abstract]
Contributions to pension plan	$ 18	$ 36.2	$ 21.2	$ 42.1

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long-term equity incentive plan, termination date	May 1, 2023
Number of shares authorized under plan	10,600,000
Number of shares available for future grants under share-based plan	700,000
Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of ROIC as performance measure	50.00%
Percentage of TSR as performance measure	50.00%

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Restricted Stock and Performance Unit Award Activity (Details)	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Restricted Stock
Restricted Stock and Performance Units [Roll Forward]
Outstanding at January 1, 2018 | shares	739,732
Granted | shares	173,144
Vested | shares	(163,436)
Forfeitures | shares	(3,738)
Outstanding at September 30, 2018 | shares	745,702
Restricted Stock and Performance Units (Weighted Average Grant-date Fair Value) [Abstract]
Weighted Average Grant-Date Fair Value, Outstanding at January 1, 2018 | $ / shares	$ 77.23
Weighted Average Grant-Date Fair Value, Granted | $ / shares	114.63
Weighted Average Grant-Date Fair Value, Vested | $ / shares	67.28
Weighted Average Grant-Date Fair Value, Forfeitures | $ / shares	81.04
Weighted Average Grant-Date Fair Value, Outstanding at September 30, 2018 | $ / shares	$ 88.07
Performance Units
Restricted Stock and Performance Units [Roll Forward]
Outstanding at January 1, 2018 | shares	226,558
Granted | shares	87,022
Vested | shares	(46,876)
Outstanding at September 30, 2018 | shares	266,704
Restricted Stock and Performance Units (Weighted Average Grant-date Fair Value) [Abstract]
Weighted Average Grant-Date Fair Value, Outstanding at January 1, 2018 | $ / shares	$ 77.07
Weighted Average Grant-Date Fair Value, Granted | $ / shares	115.33
Weighted Average Grant-Date Fair Value, Vested | $ / shares	74.46
Weighted Average Grant-Date Fair Value, Outstanding at September 30, 2018 | $ / shares	$ 90.01

Share-Based Compensation - Comp

Share-Based Compensation - Compensation Expense for Restricted Stock and Performance Units (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 6.6	$ 5.2	$ 17.4	$ 15.4
Income tax benefit	(1.6)	(2)	(4.4)	(5.9)
Share-based compensation expense, net of tax benefit	5	3.2	13	9.5
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	4.9	3.8	13.9	11.3
Performance Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 1.7	$ 1.4	$ 3.5	$ 4.1

Share-Based Compensation - Unre

Share-Based Compensation - Unrecognized Compensation Expense for Share-Based Awards (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 52.2
Remaining weighted-average recognition period	2 years 8 months 12 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 36.5
Remaining weighted-average recognition period	2 years 6 months
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 15.7
Remaining weighted-average recognition period	3 years 1 month 6 days

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions	Oct. 15, 2018	Aug. 30, 2018	May 15, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Feb. 25, 2016
Common stock dividends paid						$ 193,400,000	$ 178,200,000
Dividends declared per common share				$ 0.79	$ 0.63	$ 2.21	$ 1.89
Dividends declared date						Aug. 30, 2018
Dividends paid per common share (in dollars per share)		$ 0.79
Stock repurchase program, authorized amount									$ 200,000,000
Repurchases of common stock under stock repurchase program				0		0
Common stock repurchase authorization amount available				$ 193,000,000		$ 193,000,000
Annual Dividend [Member]
Dividends declared per common share			$ 3.16					$ 2.52
Subsequent Event
Common stock dividends paid	$ 74,700,000

Stockholders' Equity - Changes

Stockholders' Equity - Changes in Accumulated Other Comprehensive Income by Component (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1, 2018	$ (156.9)
Amounts reclassified from AOCI, net of tax	11.8
Balance at September 30, 2018	(145.1)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1, 2018	(0.3)
Amounts reclassified from AOCI, net of tax	(0.1)
Balance at September 30, 2018	(0.4)
Unfunded Employee Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1, 2018	(142.1)
Amounts reclassified from AOCI, net of tax	8.9
Balance at September 30, 2018	(133.2)
Treasury Lock | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1, 2018	(14.2)
Amounts reclassified from AOCI, net of tax	3
Balance at September 30, 2018	(11.2)
Foreign Exchange Contract | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1, 2018	(0.3)
Balance at September 30, 2018	$ (0.3)

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before taxes	[1]	$ 274.1	$ 216.9	$ 706	$ 604.6
Income tax benefit		(67.4)	(77.8)	(172.6)	(204.9)
Net income		206.7	139.1	533.4	399.7
Unfunded Employee Benefit Obligations | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service costs		(1.7)	(1.3)	(5)	(4.3)
Amortization of actuarial gains / (losses)		(2.3)	(1.8)	(6.9)	(5.6)
Income before taxes		(4)	(3.1)	(11.9)	(9.9)
Income tax benefit		1	1.2	3	3.7
Net income		(3)	(1.9)	(8.9)	(6.2)
Treasury Lock | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net		(1.3)	(1.4)	(4)	(4.2)
Income tax benefit		0.3	0.5	1	1.6
Net income		$ (1)	$ (0.9)	$ (3)	$ (2.6)
[1]	(a)Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, New and Recently Adopted Accounting Standards, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Three Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Three Months Ended September 30, 2017 Adjusted Packaging $261.5 $1.7 $263.2 Paper (0.7) (1.9) (2.6) Corporate (18.5) 0.5 (18.0) Income from operations 242.3 0.3 242.6 Interest expense, net and other (25.4) (0.3) (25.7) Income before taxes $216.9 $— $216.9 Segment income (loss) Nine Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Nine Months Ended September 30, 2017 Adjusted Packaging $676.8 $4.9 $681.7 Paper 58.1 (5.6) 52.5 Corporate (55.7) 1.6 (54.1) Income from operations 679.2 0.9 680.1 Interest expense, net and other (74.6) (0.9) (75.5) Income before taxes $604.6 $— $604.6

Stockholders' Equity - Change_2

Stockholders' Equity - Changes in Accumulated Other Comprehensive Income by Component (Parenthetical) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Equity [Abstract]
Net amount of settlement gains (losses) on derivative instruments included in accumulated OCI to be amortized over next 12 months, before tax	$ (5.2)
Net amount of settlement gains (losses) on derivative instruments included in accumulated OCI to be amortized over next 12 months, after tax	$ (3.9)

Concentrations of Risk - Additi

Concentrations of Risk - Additional Information (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Concentration Risk [Line Items]
Accounts receivable, net, current	$ 986.2		$ 830.7
Office Depot | Credit Concentration Risk
Concentration Risk [Line Items]
Accounts receivable, net, current	$ 73.5		$ 33.3
Office Depot | Total Company Sales Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%	7.00%
Office Depot | Total Company Receivables | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%		4.00%
Paper | Office Depot | Paper Segment Sales Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	46.00%	42.00%	43.00%

Transactions With Related Par_2

Transactions With Related Parties - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	$ 3.5		$ 3.5		$ 3
Carrying amount of LTP's liabilities	3.5		$ 3.5		$ 3
Boise Cascade Co-Owner of LTP
Related Party Transaction [Line Items]
Variable interest entity, ownership percentage			50.00%
Boise Cascade Co-Owner of LTP | Fiber
Related Party Transaction [Line Items]
Revenue from related parties	22.4	$ 20.8	$ 65.5	$ 66
Fiber costs from related parties	22.4	20.8	65.5	66
Boise Cascade Co-Owner of LTP | Wood Products, Including Chips and Logs
Related Party Transaction [Line Items]
Fiber costs from related parties	$ 4.1	$ 4	$ 12.8	$ 13.6
Packaging Corporation of America
Related Party Transaction [Line Items]
Variable interest entity, ownership percentage			50.00%

Segment Information - Additiona

Segment Information - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information - Selected

Segment Information - Selected Financial Information by Reportable Segment (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Segment Reporting Information [Line Items]
Net sales		$ 1,809.9		$ 1,640.1	[1]	$ 5,268.1		$ 4,760.6	[1]
Operating Income (Loss)	[2]	298.5		242.6		781		680.1
Interest expense, net and other	[2]	(24.4)		(25.7)		(75)		(75.5)
Income before taxes	[2]	274.1		216.9		706		604.6
Trade
Segment Reporting Information [Line Items]
Net sales		1,809.9		1,640.1		5,268.1		4,760.6
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales		(39.1)		(39)		(114.4)		(109.9)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Net sales		(39.1)		(39)		(114.4)		(109.9)
Packaging
Segment Reporting Information [Line Items]
Net sales		1,535.1		1,346.6	[1]	4,434.2		3,915	[1]
Operating Income (Loss)	[2]	284.4	[3]	263.2	[4]	782.3	[3]	681.7	[4],[5]
Packaging | Trade
Segment Reporting Information [Line Items]
Net sales		1,528.3		1,340.6		4,414.7		3,897.4
Packaging | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales		6.8		6		19.5		17.6
Packaging | Operating Segments
Segment Reporting Information [Line Items]
Net sales		1,535.1		1,346.6		4,434.2		3,915
Paper
Segment Reporting Information [Line Items]
Net sales		254.3		271.4	[1]	774.5		784.3	[1]
Operating Income (Loss)	[2]	32.3	[3]	(2.6)	[4]	55.7	[3]	52.5	[4]
Paper | Trade
Segment Reporting Information [Line Items]
Net sales		254.3		271.4		774.5		784.3
Paper | Operating Segments
Segment Reporting Information [Line Items]
Net sales		254.3		271.4		774.5		784.3
Corporate and Other
Segment Reporting Information [Line Items]
Net sales		20.5		22.1	[1]	59.4		61.3	[1]
Operating Income (Loss)	[2]	(18.2)	[3]	(18)		(57)	[3]	(54.1)	[4],[5]
Corporate and Other | Trade
Segment Reporting Information [Line Items]
Net sales		27.3		28.1		78.9		78.9
Corporate and Other | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales		32.3		33		94.9		92.3
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Net sales		$ 59.6		$ 61.1		$ 173.8		$ 171.2
[1]	Prior periods have not been adjusted under the modified retrospective method for Topic 606.
[2]	(a)Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, New and Recently Adopted Accounting Standards, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Three Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Three Months Ended September 30, 2017 Adjusted Packaging $261.5 $1.7 $263.2 Paper (0.7) (1.9) (2.6) Corporate (18.5) 0.5 (18.0) Income from operations 242.3 0.3 242.6 Interest expense, net and other (25.4) (0.3) (25.7) Income before taxes $216.9 $— $216.9 Segment income (loss) Nine Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Nine Months Ended September 30, 2017 Adjusted Packaging $676.8 $4.9 $681.7 Paper 58.1 (5.6) 52.5 Corporate (55.7) 1.6 (54.1) Income from operations 679.2 0.9 680.1 Interest expense, net and other (74.6) (0.9) (75.5) Income before taxes $604.6 $— $604.6
[3]	(b)The three and nine months ended September 30, 2018 include: $4.0 million and $26.4 million, respectively, of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine. $1.3 million and $1.8 million, respectively, of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility. $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. 4.$0.1 million of charges related to the Sacramento Container acquisition and integration.
[4]	(c)The three and nine months ended September 30, 2017 include: $0.9 million and $1.9 million, respectively, of charges consisting of closure costs related to corrugated products facilities, a paper administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. $0.5 million and $0.8 million, respectively, of charges related to the Sacramento Container Corporation acquisition and integration costs related to other recent acquisitions. $25.3 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine.
[5]	(d)The nine months ended September 30, 2017 include: 1.$5.0 million of costs for the property damage and business interruption insurance deductible corresponding to the February 2017 explosion at our DeRidder, Louisiana mill. 2.$2.3 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

Segment Information - Selecte_2

Segment Information - Selected Financial Information by Reportable Segment (Parenthetical) (Details) - USD ($) $ in Millions		3 Months Ended					9 Months Ended
		Sep. 30, 2018		Jun. 30, 2018	Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Segment Reporting Information [Line Items]
Operating Income (Loss)	[1]	$ 298.5			$ 242.6		$ 781		$ 680.1
Interest expense, net and other	[1]	(24.4)			(25.7)		(75)		(75.5)
Income before taxes	[1]	274.1			216.9		706		604.6
Acquisition and integration related costs	[2]	0.1			0.5		0.1		0.8
Sacramento Container Corporation
Segment Reporting Information [Line Items]
Acquisition and integration related costs		0.1			0.5		0.1		0.8
Wallula, Washington Mill
Segment Reporting Information [Line Items]
High-performance of virgin kraft linerboard machine percentage				100.00%
ASU 2017-07
Segment Reporting Information [Line Items]
Operating Income (Loss)					242.3
Interest expense, net and other					(25.4)
Income before taxes					216.9
ASU 2017-07 | As Reported
Segment Reporting Information [Line Items]
Operating Income (Loss)									679.2
Interest expense, net and other									(74.6)
Income before taxes									604.6
ASU 2017-07 | Non-Operating Pension Adjustment
Segment Reporting Information [Line Items]
Operating Income (Loss)					0.3				0.9
Interest expense, net and other					(0.3)				(0.9)
Packaging
Segment Reporting Information [Line Items]
Operating Income (Loss)	[1]	284.4	[3]		263.2	[4]	782.3	[3]	681.7	[4],[5]
Property damage and business interruption insurance		0.5					0.5
Packaging | Hexacomb Europe and Mexico
Segment Reporting Information [Line Items]
Acquisition and integration related costs									2.3
Packaging | Deridder Mill
Segment Reporting Information [Line Items]
Property damage and business interruption insurance					5				5
Packaging | ASU 2017-07
Segment Reporting Information [Line Items]
Operating Income (Loss)					261.5
Packaging | ASU 2017-07 | As Reported
Segment Reporting Information [Line Items]
Operating Income (Loss)									676.8
Packaging | ASU 2017-07 | Non-Operating Pension Adjustment
Segment Reporting Information [Line Items]
Operating Income (Loss)					1.7				4.9
Paper
Segment Reporting Information [Line Items]
Operating Income (Loss)	[1]	32.3	[3]		(2.6)	[4]	55.7	[3]	52.5	[4]
Paper | Wallula, Washington Mill
Segment Reporting Information [Line Items]
Restructuring charges		$ 4			$ 25.3		$ 26.4		$ 25.3
High-performance of virgin kraft linerboard machine percentage		100.00%			100.00%		100.00%		100.00%
Paper | ASU 2017-07
Segment Reporting Information [Line Items]
Operating Income (Loss)					$ (0.7)
Paper | ASU 2017-07 | As Reported
Segment Reporting Information [Line Items]
Operating Income (Loss)									$ 58.1
Paper | ASU 2017-07 | Non-Operating Pension Adjustment
Segment Reporting Information [Line Items]
Operating Income (Loss)					(1.9)				(5.6)
Corporate
Segment Reporting Information [Line Items]
Operating Income (Loss)	[1]	$ (18.2)	[3]		(18)		$ (57)	[3]	(54.1)	[4],[5]
Corporate | ASU 2017-07
Segment Reporting Information [Line Items]
Operating Income (Loss)					(18.5)
Corporate | ASU 2017-07 | As Reported
Segment Reporting Information [Line Items]
Operating Income (Loss)									(55.7)
Corporate | ASU 2017-07 | Non-Operating Pension Adjustment
Segment Reporting Information [Line Items]
Operating Income (Loss)					0.5				1.6
Packaging And Corporate And Other
Segment Reporting Information [Line Items]
Restructuring charges		$ 1.3			$ 0.9		$ 1.8		$ 1.9
[1]	(a)Effective January 1, 2018, the Company adopted ASU 2017-07, Compensation: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost and applied this standard retrospectively to the prior period reflected herein. This new standard requires the presentation of non-service cost components of net periodic benefits expense to be shown separately outside the subtotal of operating income in the income statement. See Note 2, New and Recently Adopted Accounting Standards, for more information. The components of our financial statements affected by the change in presentation of operating and non-operating pension expense as originally reported in 2017 and as adjusted for the requirements per the new standard are as follows (dollars in millions): Segment income (loss) Three Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Three Months Ended September 30, 2017 Adjusted Packaging $261.5 $1.7 $263.2 Paper (0.7) (1.9) (2.6) Corporate (18.5) 0.5 (18.0) Income from operations 242.3 0.3 242.6 Interest expense, net and other (25.4) (0.3) (25.7) Income before taxes $216.9 $— $216.9 Segment income (loss) Nine Months Ended September 30, 2017 As Reported Non-Operating Pension Adjustment Nine Months Ended September 30, 2017 Adjusted Packaging $676.8 $4.9 $681.7 Paper 58.1 (5.6) 52.5 Corporate (55.7) 1.6 (54.1) Income from operations 679.2 0.9 680.1 Interest expense, net and other (74.6) (0.9) (75.5) Income before taxes $604.6 $— $604.6
[2]	Includes charges related to recent acquisitions and the integration of recent acquisitions.
[3]	(b)The three and nine months ended September 30, 2018 include: $4.0 million and $26.4 million, respectively, of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine. $1.3 million and $1.8 million, respectively, of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility. $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. 4.$0.1 million of charges related to the Sacramento Container acquisition and integration.
[4]	(c)The three and nine months ended September 30, 2017 include: $0.9 million and $1.9 million, respectively, of charges consisting of closure costs related to corrugated products facilities, a paper administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. $0.5 million and $0.8 million, respectively, of charges related to the Sacramento Container Corporation acquisition and integration costs related to other recent acquisitions. $25.3 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine.
[5]	(d)The nine months ended September 30, 2017 include: 1.$5.0 million of costs for the property damage and business interruption insurance deductible corresponding to the February 2017 explosion at our DeRidder, Louisiana mill. 2.$2.3 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

Commitments, Guarantees, Inde_2

Commitments, Guarantees, Indemnifications, and Legal Proceedings - Additional Information (Details) - DeRidder, Louisiana - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Feb. 08, 2017
Schedule Of Commitments And Contingencies [Line Items]
Loss contingency, period of occurrence			February 8, 2017
Liability insurance				$ 1,000,000
Property damages and business interruption insurance				$ 5,000,000
Claim with insurance carrier		$ 17,000,000
Insurance proceeds included in net cash provided by operating activities		14,500,000
Insurance proceeds included in net cash provided by investing activities		$ 2,500,000
Payment of penalties	$ 40,000