Packaging Corporation of America (PKG) 10-K 26 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jun. 30, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	PKG
Entity Registrant Name	PACKAGING CORP OF AMERICA
Security Exchange Name	NYSE
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity Interactive Data Current	Yes
Entity File Number	1-15399
Entity Tax Identification Number	36-4277050
Entity Address, Address Line One	1 North Field Court
Entity Address, City or Town	Lake Forest
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60045
City Area Code	847
Local Phone Number	482-3000
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Entity Central Index Key	0000075677
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		94,652,815
Entity Public Float			$ 8,891,651,488
Documents Incorporated by Reference	Specified portions of the Proxy Statement for the Registrant's 2020 Annual Meeting of Stockholders are incorporated by reference to the extent indicated in Part III of this Form 10-K.

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Net sales	$ 6,964.3	$ 7,014.6	$ 6,444.9	[1]
Cost of sales	(5,320.3)	(5,369.3)	(4,974.1)
Gross profit	1,644	1,645.3	1,470.8
Selling and administrative expenses	(557.6)	(536.4)	(519.9)
Other expense, net	(32.7)	(41.2)	(18.4)
Income from operations	1,053.7	1,067.7	932.5	[2]
Non-operating pension expense	(7.9)	(2.1)	(1.3)
Interest expense, net	(128.8)	(95.1)	(102.6)
Income before taxes	917	970.5	828.6	[2]
Provision for income taxes	(220.6)	(232.5)	(160)
Net income	$ 696.4	$ 738	$ 668.6
Net income per common share:
Basic	$ 7.36	$ 7.82	$ 7.09
Diluted	7.34	7.80	7.07
Dividends declared per common share	$ 3.16	$ 3	$ 2.52
Statements of Comprehensive Income:
Net income	$ 696.4	$ 738	$ 668.6
Foreign currency translation adjustment		(0.1)	(0.2)
Reclassification adjustments to cash flow hedges included in net income, net of tax of $7.9 million, $1.3 million, and $2.2 million for 2019, 2018, and 2017, respectively	10.2	4	3.5
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $3.2 million, $4.0 million, and $4.9 million for 2019, 2018, and 2017, respectively	9.6	11.8	8.2
Changes in unfunded employee benefit obligations, net of tax of $13.6 million, ($0.8) million, and $18.0 million for 2019, 2018, and 2017, respectively	(40.5)	2.4	(28.8)
Other comprehensive income (loss)	(20.7)	18.1	(17.3)
Comprehensive income	$ 675.7	$ 756.1	$ 651.3
[1]	2017 has not been adjusted under the modified retrospective method for Topic 606.
[2]	Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

Consolidated Statements of In_2

Consolidated Statements of Income and Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Reclassification adjustments to cash flow hedges included in net income, tax	$ 7.9	$ 1.3	$ 2.2
Amortization of pension and postretirement plans actuarial loss and prior service cost, tax	3.2	4	4.9
Changes in unfunded employee benefit obligations, tax	$ 13.6	$ (0.8)	$ 18

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 679.5	$ 361.5
Short-term marketable debt securities	87.9
Accounts receivable, net of allowance for doubtful accounts and customer deductions of $12.6 million and $13.6 million as of December 31, 2019 and 2018, respectively	845.6	901.9
Inventories	794.1	795.6
Prepaid expenses and other current assets	44.8	39.4
Federal and state income taxes receivable	26.5	16.7
Total current assets	2,478.4	2,115.1
Property, plant and equipment, net	3,151.7	3,108.6
Goodwill	918.7	917.3
Other intangible assets, net	338.8	378.2
Operating lease right-of-use assets	234.3
Long-term marketable debt securities	58.1
Other long-term assets	55.8	50.5
Total assets	7,235.8	6,569.7
Current liabilities:
Operating lease obligations	62.6
Finance lease obligations	1.5	1.4
Accounts payable	351.9	382.2
Dividends payable	76.6	76.1
Accrued liabilities	217.5	222.4
Accrued interest	13.7	11.5
Total current liabilities	723.8	693.6
Long-term liabilities:
Long-term debt	2,476.8	2,483.7
Operating lease obligations	177.6
Finance lease obligations	16	17.6
Deferred income taxes	340.1	285.2
Compensation and benefits	375.5	357.5
Other long-term liabilities	55	59.7
Total long-term liabilities	3,441	3,203.7
Commitments and contingent liabilities
Stockholders' equity:
Common stock, par value $0.01 per share, 300.0 million shares authorized, 94.7 million and 94.5 million shares issued as of December 31, 2019 and 2018, respectively	0.9	0.9
Additional paid in capital	524.8	494.5
Retained earnings	2,704.8	2,315.8
Accumulated other comprehensive loss	(159.5)	(138.8)
Total stockholders' equity	3,071	2,672.4
Total liabilities and stockholders' equity	$ 7,235.8	$ 6,569.7

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Allowance for doubtful accounts and customer deductions	$ 12.6	$ 13.6
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	94,700,000	94,500,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 696.4		$ 738		$ 668.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, and amortization of intangibles	387.5		410.9		391.4
Amortization of deferred financing costs	23.4		8.6		10
Loss on early extinguishment of debt	22.2
Share-based compensation expense	30.4		23.5		20.6
Deferred income tax provision (benefit)	60.3		38.7		(84.5)
Net loss on impairment of assets			3.1		13.5
Pension and post-retirement benefits expense, net of contributions	(26.9)		3.1		(20.4)
Other, net	4.8		7.1		3
Decrease (increase) in assets —
Accounts receivable	56.4		(56.1)		(115.1)
Inventories	1.4		(35.6)		(21)
Prepaid expenses and other current assets	(6.9)		(2.1)		(5.2)
(Decrease) increase in liabilities —
Accounts payable	(32.4)		(17.6)		41
Accrued liabilities	(0.1)		5.5		8.4
Federal and state income tax payable / receivable	(9.1)		53		(54.2)
Net cash provided by operating activities	1,207.4		1,180.1		856.1
Cash Flows from Investing Activities:
Additions to property, plant, and equipment	(399.5)	[1]	(551.4)	[1]	(343)
Acquisitions of businesses, net of cash acquired			(56.3)		(273.8)
Additions to other long term assets	(3.8)		(4.5)		(7.8)
Proceeds from asset disposals	4.1		1.5		16.6
Purchases of marketable debt securities, net of redemptions	(146.1)
Other, net	(1.3)		2.5		(1.1)
Net cash used for investing activities	(546.6)		(608.2)		(609.1)
Cash Flows from Financing Activities:
Proceeds from issuance of debt	895.8				997.8
Repayments of debt and capital lease obligations	(923.4)		(151.3)		(1,011.9)
Financing costs paid	(8.3)				(6.8)
Common stock dividends paid	(298.7)		(268.1)		(237.6)
Shares withheld to cover employee restricted stock taxes	(8.2)		(7.9)		(10.8)
Other, net					(0.1)
Net cash used for financing activities	(342.8)		(427.3)		(269.4)
Net increase (decrease) in cash and cash equivalents	318		144.6		(22.4)
Cash and cash equivalents, beginning of year	361.5		216.9		239.3
Cash and cash equivalents, end of year	$ 679.5		$ 361.5		$ 216.9
[1]	Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2016	$ 1,759.8	$ 0.9	$ 451.4	$ 1,447.1	$ (139.6)
Beginning Balance (in shares) at Dec. 31, 2016		94,213
Common stock withheld and retired to cover taxes on vested stock awards	(10.8)	$ 0	(0.7)	(10.1)	0
Common stock withheld and retired to cover taxes on vested stock awards (in shares)		(98)
Common stock dividends declared	(238.2)	$ 0	0	(238.2)	0
Share-based compensation expense	20.6	$ 0	20.6	0	0
Share-based compensation expense (in shares)		235
Other	(0.1)	$ 0	(0.1)	0	0
Comprehensive income	651.3	0	0	668.6	(17.3)
Ending Balance at Dec. 31, 2017	2,182.6	$ 0.9	471.2	1,867.4	(156.9)
Ending Balance (in shares) at Dec. 31, 2017		94,350
Common stock withheld and retired to cover taxes on vested stock awards	(7.9)	$ 0	(0.5)	(7.4)	0
Common stock withheld and retired to cover taxes on vested stock awards (in shares)		(69)
Common stock dividends declared	(284)	$ 0	0	(284)	0
Share-based compensation expense	23.5	$ 0	23.5	0	0
Share-based compensation expense (in shares)		216
Adoption of ASC 606 | ASU 2014-09	1.6	$ 0	0	1.6	0
Other	0.5	0	0.3	0.2	0
Comprehensive income	756.1	0	0	738	18.1
Ending Balance at Dec. 31, 2018	2,672.4	$ 0.9	494.5	2,315.8	(138.8)
Ending Balance (in shares) at Dec. 31, 2018		94,497
Common stock withheld and retired to cover taxes on vested stock awards	(8.2)	$ 0	(0.7)	(7.5)	0
Common stock withheld and retired to cover taxes on vested stock awards (in shares)		(87)
Common stock dividends declared	(299.7)	$ 0	0	(299.7)	0
Share-based compensation expense	31	$ 0	31	0	0
Share-based compensation expense (in shares)		245
Other	(0.2)	$ 0	0	(0.2)	0
Comprehensive income	675.7	0	0	696.4	(20.7)
Ending Balance at Dec. 31, 2019	$ 3,071	$ 0.9	$ 524.8	$ 2,704.8	$ (159.5)
Ending Balance (in shares) at Dec. 31, 2019		94,655

Nature of Operations and Basis

Nature of Operations and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
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 have approximately 15,500 employees. We report our business in three reportable segments: Packaging, Paper, and Corporate and Other. Our Packaging segment produces a wide variety of containerboard and 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 white paper grades at the Wallula, Washington mill and converted the No. 3 machine at the mill from production of white papers to production of virgin kraft linerboard. Before May 2018, operating results for the Wallula mill were included in the Paper segment. After 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 20, 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 include the accounts of PCA and its majority-owned subsidiaries after elimination of intercompany balances and transactions.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. These estimates and assumptions are based on management's best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment. We adjust such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in these estimates will be reflected in the consolidated financial statements in future periods. Revenue Recognition In accordance with ASU 2014-09 (Topic 606): Revenue from Contracts with Customers Planned Major Maintenance Costs The Company accounts for its planned major maintenance activities in accordance with ASC 360, Property, Plant, and Equipment Share-Based Compensation We recognize compensation expense for awards granted under the PCA long-term equity incentive plans based on the fair value on the grant date. We recognize the cost of the equity awards expected to vest over the period the awards vest. See Note 15, Share-Based Compensation, for more information. Research and Development Research and development costs are expensed as incurred. The amount charged to expense was $16.0 million, $14.4 million, and $12.8 million for the years ended December 31, 2019, 2018, and 2017, respectively. Cash and Cash Equivalents Cash and cash equivalents include all cash balances and highly liquid investments with original maturities of three months or less at the date of purchase. Cash equivalents are stated at cost, which approximates market. Cash and cash equivalents totaled $679.5 million and $361.5 million at December 31, 2019 and 2018, respectively, which included cash equivalents of $410.7 million Marketable Debt Securities The Company’s marketable debt securities have been classified and accounted for as available-for-sale (AFS) in accordance with ASU 2016-01, Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities Changes in the fair value of marketable debt securities impact net income only when such securities are sold or an other-than-temporary impairment is recognized. The Company regularly reviews its investment portfolio to determine if any marketable debt security is other-than-temporarily impaired. In making this judgment, PCA evaluates, among other things, the duration and the extent to which the fair value of a marketable debt security is less than its cost; the financial condition of the issuer and any changes thereto; and the intent to sell, or whether we will more likely than not be required to sell, the marketable debt security before recovery of its amortized cost basis. We recorded no other-than-temporary impairment charges on our AFS securities for the year ended December 31, 2019. We did not have any marketable debt securities for the year ended December 31, 2018. See Note 12, Cash, Cash Equivalents, and Marketable Debt Securities, for more information. Trade Accounts Receivable, Allowance for Doubtful Accounts, and Customer Deductions Trade accounts receivable are stated at the amount we expect to collect. The collectability of our accounts receivable is based upon a combination of factors. In circumstances where a specific customer is unable to meet its financial obligations to PCA (e.g., bankruptcy filings, substantial downgrading of credit sources), a specific reserve for bad debts is recorded against amounts due to the Company to reduce the net recorded receivable to the amount the Company reasonably believes will be collected. For all other customers, reserves for bad debts are recognized based on historical collection experience. If collection experience deteriorates (i.e., higher than expected defaults or an unexpected material adverse change in a major customer’s ability to meet its financial obligations to the Company), the estimate of the recoverability of amounts due could be reduced by a material amount. We periodically review our allowance for doubtful accounts and adjustments to the valuation allowance are recorded as income or expense. Trade accounts receivable balances that remain outstanding after we have used reasonable collection efforts are written off through a charge to the valuation allowance and a credit to accounts receivable. At December 31, 2019 and 2018, the allowance for doubtful accounts was $4.2 million and $4.6 million, respectively. The customer deductions reserve represents the estimated amount required for customer returns, allowances, and earned discounts. Based on the Company’s experience, customer returns, allowances, and earned discounts have averaged approximately 1% of gross selling price. Accordingly, PCA reserves 1% of its open customer accounts receivable balance for these items. The reserves for customer deductions of $8.4 million Derivative Instruments and Hedging Activities The Company records its derivatives, if any, in accordance with ASC 815, Derivatives and Hedging Fair Value Measurements PCA measures the fair value of its financial instruments and marketable debt securities in accordance with ASC 820, Fair Value Measurements and Disclosures Level 1 — Valuations based on quoted prices for identical assets and liabilities in active markets. Level 2 — Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data. Level 3 — Valuations based on unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Assets that are measured at fair value using the net asset value (NAV) per share as a practical expedient are not categorized within the fair value hierarchy. Financial instruments and marketable debt securities measured at fair value on a recurring basis include the fair values of our marketable debt securities and our pension and postretirement benefit assets and liabilities. See Note 12, Cash, Cash Equivalents, and Marketable Debt Securities, and Note 13, Employee Benefit Plans and Other Postretirement Benefits, for more information. Other assets and liabilities measured and recognized at fair value on a nonrecurring basis include assets acquired and liabilities assumed in acquisitions and our asset retirement obligations. Given the nature of these assets and liabilities, evaluating their fair value from the perspective of a market participant is inherently complex. Assumptions and estimates about future values can be affected by a variety of internal and external factors. Changes in these factors may require us to revise our estimates and could require us to retroactively adjust provisional amounts that we recorded for the fair values of assets acquired and liabilities assumed in connection with business combinations. These adjustments could have a material effect on our financial condition and results of operations. See Note 5, Acquisitions, and Note 14, Asset Retirement Obligations, for more information. 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. The components of inventories were as follows (dollars in millions): December 31, 2019 2018 Raw materials $ 271.5 $ 307.8 Work in process 11.0 13.9 Finished goods 207.7 199.0 Supplies and materials 303.9 274.9 Inventories $ 794.1 $ 795.6 Property, Plant, and Equipment Property, plant, and equipment are recorded at cost. Cost includes expenditures for major improvements and replacements and the amount of interest cost associated with significant capital additions. Repairs and maintenance costs are expensed as incurred . Property, plant, and equipment consisted of the following (dollars in millions): December 31, 2019 2018 Land and land improvements $ 177.5 $ 161.9 Buildings 837.4 795.5 Machinery and equipment 5,727.4 5,481.6 Construction in progress 174.0 176.7 Other 81.5 75.4 Property, plant and equipment, at cost 6,997.8 6,691.1 Less accumulated depreciation (3,846.1 ) (3,582.5 ) Property, plant and equipment, net $ 3,151.7 $ 3,108.6 The amount of interest capitalized from construction in progress was $3.4 million, $4.5 million, and $2.5 million for the years ended December 31, 2019, 2018, and 2017, respectively. Depreciation is computed on the straight-line basis over the estimated useful lives of the related assets. Assets under finance leases are depreciated on the straight-line method over the term of the lease or the useful life, if shorter. The following lives are used for the various categories of assets: Buildings and land improvements 5 to 40 years Machinery and equipment 3 to 25 years Trucks and automobiles 3 to 10 years Furniture and fixtures 3 to 20 years Computers and hardware 3 to 10 years Leasehold improvements Period of the lease life, if shorter The amount of depreciation expense was $346.8 million, $361.7 million, and $347.8 million for the years ended December 31, 2019, 2018, and 2017, respectively. In 2019, 2018, and 2017, we recognized incremental depreciation expense of $0.3 million, $14.5 million, and $10.5 million, respectively, primarily related to the second quarter 2018 discontinuation of paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. Pursuant to the terms of an industrial revenue bond, title to certain property, plant, and equipment was transferred to a municipal development authority in 2009 in order to receive a property tax abatement. The title of these assets will revert back to PCA upon retirement or cancellation of the bond. The assets are included in the consolidated balance sheets under the caption “Property, plant, and equipment, net” as all risks and rewards remain with the Company. Leases We determine if an arrangement is, or contains, a lease at the inception date based on the presence of identified assets and our right to obtain substantially all of the economic benefit from or to direct the use of such assets. When we determine a lease exists, we record a right-of-use asset and corresponding lease liability on our consolidated balance sheets. Right-of-use assets represent our right to use an underlying asset for the lease term. Lease liabilities represent our obligation to make lease payments arising from the lease. Right-of-use assets are recognized at commencement date at the value of the lease liability and are adjusted for any prepayments, lease incentives received, and initial direct costs incurred. Lease liabilities are recognized at lease commencement date based on the present value of remaining lease payments over the lease term. As the discount rate implicit in the lease is not readily determinable in most of our leases, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. Our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease balances are included in Operating lease right-of-use assets with the related liabilities included in Current Operating lease obligations and Long-term Operating lease obligations. Assets under finance leases are included in Property, plant and equipment, net, with the related liabilities included in Current Finance lease obligations and Long-term Finance lease obligations . We do not record lease contracts with a term of 12 months or less on our consolidated balance sheets. We recognize fixed lease expense for operating leases on a straight-line basis over the lease term. For finance leases, we recognize amortization expense on the right-of-use asset and interest expense on the lease liability over the lease term. We have lease agreements with non-lease components that relate to lease components (e.g., common area maintenance such as cleaning or landscaping, insurance, etc.). We account for each lease and any non-lease components associated with that lease as a single lease Long-Lived Asset Impairment Long-lived assets other than goodwill and other intangibles are reviewed for impairment in accordance with provisions of ASC 360, Property, Plant and Equipment Goodwill and Intangible Assets The Company has capitalized certain intangible assets, primarily goodwill, customer relationships, and trademarks and trade names, based on their estimated fair value at the date of acquisition. Amortization is provided for customer relationships on a straight-line basis over periods ranging from ten to 40 years, and trademarks and trade names over periods ranging from five to 20 years. Goodwill, which amounted to $918.7 million and $917.3 million for the years ended December 31, 2019 and 2018, respectively, is not amortized but is subject to an annual impairment test in accordance with ASC 350, Intangibles – Goodwill and Other. Pension and Postretirement Benefits Several estimates and assumptions are required to record pension costs and liabilities, including discount rate, return on assets, and longevity and service lives of employees. We review and update these assumptions annually unless a plan curtailment or other event occurs, requiring that we update the estimates on an interim basis. While we believe the assumptions used to measure our pension and postretirement benefit obligations are reasonable, differences in actual experience or changes in assumptions may materially affect our pension and postretirement benefit obligations and future expense. See Note 13, Employee Benefit Plans and Other Postretirement Benefits, for additional information. For postretirement health care plan accounting, the Company reviews external data and its own historical trends for health care costs to determine the health care cost trend rate assumption. Environmental Matters Environmental expenditures that extend the life of the related property or mitigate or prevent future environmental contamination are capitalized. Liabilities are recorded for environmental contingencies when such costs are probable and reasonably estimable. These liabilities are adjusted as further information develops or circumstances change. Environmental expenditures related to existing conditions resulting from past or current operations from which no current or future benefit is discernible are expensed as incurred. Asset Retirement Obligations The Company accounts for its retirement obligations related predominantly to landfill closure, wastewater treatment pond dredging, closed-site monitoring costs, and certain leasehold improvements under ASC 410, Asset Retirement and Environmental Obligations Deferred Debt Issuance Costs PCA has capitalized certain costs related to obtaining its financing. These costs are amortized to interest expense using the effective interest rate method over the terms of the related financing, which range from 10 to 30 years. At December 31, 2019 and 2018 deferred debt issuance costs were $16.3 million and $12.6 million, respectively, and were recorded in “Long-Term Debt” on our Consolidated Balance Sheets. Cutting Rights and Fiber Farms We lease the cutting rights to approximately 73,000 acres of timberland. Additionally, we previously leased 3,000 acres of land where we operated fiber farms as a source of future fiber supply; however, we exited the leases in conjunction with the conversion of the No. 3 machine at the Wallula mill to produce virgin kraft linerboard. Management performed a recoverability test on the associated fiber farms in 2018 and 2017 and deemed the asset group to not be fully recoverable. As a result of the recoverability calculation on the fiber farm asset group, the Company recorded an impairment loss of $3.1 million and $13.5 million in 2018 and 2017, respectively. For our cutting rights, we capitalize the annual lease payments and reforestation costs associated with these leases. Costs are recorded as depletion when the timber or fiber is harvested and used in operations or sold to customers. Capitalized long-term lease costs for our cutting rights, primarily recorded in “Other long-term assets” on our Consolidated Balance Sheets, were $21.6 million and $22.4 million as of December 31, 2019 and 2018, respectively. The amount of depletion expense was $2.7 million, $7.6 million, and $5.2 million for the years ended December 31, 2019, 2018, and 2017, respectively. Deferred Software Costs PCA capitalizes costs related to the purchase and development of software, which is used in its business operations. The costs attributable to these software systems are amortized over their estimated useful lives based on various factors such as the effects of obsolescence, technology, and other economic factors. Net capitalized software costs recorded in “Other long-term assets” on our Consolidated Balance Sheets were $1.4 million and $1.6 million for the years ended December 31, 2019 and 2018, respectively. Software amortization expense was $0.9 million, $2.1 million, and $2.3 million for the years ended December 31, 2019, 2018, and 2017, respectively. During 2019, the Company early adopted ASU 2018-15, Intangibles – Goodwill and Other – Internal Use Software Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract Income Taxes PCA utilizes the liability method of accounting for income taxes whereby it recognizes deferred tax assets and liabilities for the future tax consequences of temporary differences between the tax basis of assets and liabilities and the reported amounts in the financial statements. Deferred tax assets will be reduced by a valuation allowance if, based upon management’s estimates, it is more likely than not that a portion of the deferred tax assets will not be realized in a future period. The estimates utilized in the recognition of deferred tax assets are subject to revision in future periods based on new facts or circumstances. PCA’s practice is to recognize interest and penalties related to unrecognized tax benefits in income tax expense. Trade Agreements PCA regularly trades containerboard with other manufacturers primarily to reduce shipping costs. These agreements are entered into with other producers on an annual basis, pursuant to which both parties agree to ship an identical number of tons of containerboard to each other within the agreement period. These agreements lower transportation costs by allowing each party’s containerboard mills to ship containerboard to the other party’s closer corrugated products plant. PCA tracks each shipment to ensure that the other party’s shipments to PCA match PCA’s shipments to the other party during the agreement period. Such transfers are possible because containerboard is a commodity product with no distinguishing product characteristics. These transactions are accounted for at carrying value, and revenue is not recorded as the transactions do not represent the culmination of an earnings process. The transactions are recorded into inventory accounts, and no sale or income is recorded until such inventory is converted to a finished product and sold to an end-use customer. Business Combinations The Company accounts for acquisitions under ASC 805, Business Combinations Clarifying the Definition of a Business Recently Adopted Accounting Standards Effective January 1, 2019, the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2016-02 (Topic 842): Leases , which requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous guidance. The original guidance required application on a modified retrospective basis with the earliest period presented. In July 2018, the FASB issued ASU 2018-11, Targeted Improvements to ASC 842 , which included an option to not restate comparative periods in transition and elect to use the effective date of ASC 842, Leases , as the date of initial application of transition, which we elected. As a result of the adoption of ASC 842 on January 1, 2019, we recorded operating lease liabilities of $228 million, with corresponding right-of-use assets of the same amount. In addition, we elected the package of practical expedients permitted under the transition guidance within the new standard, which allowed us to carry forward the historical lease classification and not to reassess whether existing or expired contracts contain a lease. We also elected the short-term lease recognition exemption, which permits us to exclude short-term leases (i.e. leases with terms of 12 months or less) from the recognition requirements of this standard, and we elected to account for lease and non-lease components as a single lease component for all classes of underlying assets except for embedded leases. The adoption of ASC 842 had an immaterial impact on our consolidated net earnings, liquidity and debt covenants under our current agreements for the year ended December 31, 2019. See Note 3, Leases, for more information. Effective January 1, 2019, we adopted ASU 2018-02 (Topic 220 ): Income Statement—Reporting Comprehensive Income – Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income Tax Act. As a result, the adoption did not have an impact on the Company's financial position, results of operations, or cash flow . Effective October 1, 2019, we early adopted ASU 2018-15, Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which includes amendments to align the accounting for costs incurred to implement a cloud computing arrangement that is a service contract with the guidance on capitalizing costs associated with developing or obtaining internal-use software. The accounting for the service component of a hosting arrangement that is a service contract is not affected by the amendments in this update. This guidance will be applied prospectively. The adoption of this guidance did not have a material impact on the Company’s financial condition, results of operations, or cash flows. 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 of this guidance, but does not expect the guidance will have a significant impact 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 this guidance, but does not expect the guidance will have a significant impact on its related disclosures. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) : Measurement of Credit Losses on Financial Instruments. ASU 2016-13 introduces the Current Expected Credit Losses (“CECL”) framework for evaluating credit losses on financial instruments measured at amortized cost. This new framework requires entities to incorporate forward-looking information into their estimate of current expected credit loss as of each reporting date. Although available-for-sale (“AFS”) debt securities are not within the scope of the new CECL framework, the ASU includes an amended impairment model for evaluating losses related to AFS debt securities. The guidance in this update also includes enhanced requirements for disclosures related to credit loss estimates. The ASU is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. The amendments in ASU 2016-13 would need to be applied using the modified retrospective method. The Company is currently evaluating the impact of the new guidance but does not expect this ASU to have a material impact on the Company’s financial position, results of operation, or cash flow. 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.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	3. Leases We group our leases into two primary lease types, real estate and equipment, and into various asset classes within each type. Real estate leases primarily include manufacturing locations, office space, warehouses, and design centers, while equipment leases primarily include manufacturing equipment. Leases with an initial term of 12 months or less and certain month-to-month leases are not recorded on the balance sheet. The lease expense for these types of leases is recognized on a straight-line basis over the lease term. To determine the lease term, we include the non-cancellable period of the lease together with the following: all periods covered by an option to extend the lease if we are reasonably certain to exercise that option; any periods covered by an option to terminate the lease if we are reasonably certain not to exercise that option; and any periods covered by an option to extend or not to terminate the lease that are controlled by the lessor. The exercising of lease renewal options is based on whether future economic benefit is expected to be derived from the renewal. Most of our real estate leases contain at least one renewal option. Renewal options generally range from 1 to 5 years . Although equipment leases may also contain renewal options, we typically do not expect to extend and/or exercise these renewal options unless a compelling business reason is provided to management . Our leases may contain fixed and variable costs. Fixed costs determine the right-of-use asset. Variable costs are those costs which will vary month to month and are excluded from the calculation of the right-of-use asset. Variable lease costs are recorded to lease expense in the period in which they are incurred. Our leases do not provide an implicit borrowing rate of return. Therefore, we use our incremental borrowing rate to calculate the present value of lease payments at inception of the lease or when a lease is modified. Supplemental balance sheet information related to our operating leases at December 31, 2019 was as follows (dollars in millions): Operating lease right-of-use assets $ 234.3 Current portion of operating lease obligations $ 62.6 Long-term portion of operating lease obligations 177.6 Total operating lease obligations $ 240.2 Supplemental balance sheet information related to our finance leases was as follows (dollars in millions): Year Ended December 31, 2019 2018 Buildings $ 0.3 $ 0.3 Machinery and equipment 28.5 28.5 Total 28.8 28.8 Less accumulated amortization (18.1 ) (16.7 ) Total $ 10.7 $ 12.1 Current portion of finance lease obligations $ 1.5 $ 1.4 Long-term portion of finance lease obligations 16.0 17.6 Total finance lease obligations $ 17.5 $ 19.0 The Company was obligated under finance leases covering buildings and machinery and equipment in the amount of $17.5 million For both operating and finance leases, the weighted average remaining lease term in years and weighted average discount rates at December 31, 2019 were as follows: Weighted-average remaining lease term (years): Operating leases 5.6 Finance leases 8.8 Weighted-average discount rate: Operating leases 4.23% Finance leases 6.66% The components of lease expense for the full year ended December 31, 2019 were as follows (dollars in millions): Finance lease cost: Amortization of finance lease assets $ 1.5 Interest on lease liabilities 1.2 Total finance lease cost 2.7 Operating lease cost 70.2 Short-term lease cost 19.2 Variable lease cost 13.7 Total lease cost $ 105.8 Total lease expense, including base rent on all leases and executory costs, such as insurance, taxes, and maintenance, for the years ended December 31, 2018 and 2017 was $115.1 million and $100.6 million, respectively. These costs are included in “Cost of sales” and “Selling, general, and administrative expenses” in our Consolidated Statements of Income. We had an insignificant amount of sublease rental income for the year ended December 31, 2019 and no sublease rental income for the years ended December 31, 2018 and 2017. Interest expense related to finance lease obligations for the years ended December 31, 2018 and 2017 was $1.3 million and $1.4 million, respectively. Supplemental cash flow information related to leases for the full year ended December 31, 2019 was as follows (dollars in millions): Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ (60.0 ) Operating cash flows for finance leases (1.5 ) Financing cash flows for finance leases (1.2 ) Right-of-use assets obtained in exchange for new lease obligations: Operating leases $ (27.7 ) Finance leases — Supplemental non-cash information on changes in lease liabilities $ 44.5 Supplemental non-cash information on changes in right-of-use assets $ 21.4 The future minimum payments under operating and finance lease liabilities at December 31, 2019 were as follows (dollars in millions): Operating Leases Finance Leases 2020 $ 71.2 $ 2.7 2021 60.6 2.7 2022 42.8 2.7 2023 28.7 2.7 2024 20.2 2.7 Thereafter 48.0 9.7 Total lease payments 271.5 23.2 Less imputed interest (a) (31.3 ) (5.7 ) Present value of lease liabilities $ 240.2 $ 17.5 (a) Calculated using the incremental borrowing rate for each lease applied to the future payments. The future minimum payments under operating and finance lease liabilities at December 31, 2018 under ASC 840 were as follows (dollars in millions): Operating Leases Finance Leases 2019 $ 70.1 $ 2.7 2020 58.7 2.7 2021 47.4 2.7 2022 29.9 2.7 2023 17.8 2.7 Thereafter 46.4 12.4 Total lease payments $ 270.3 25.9 Less imputed interest (b) (6.9 ) Present value of lease liabilities $ 19.0 (b) Calculated using the incremental borrowing rate for each lease applied to the future payments.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2019
Revenue From Contract With Customer [Abstract]
Revenue	4 . 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 received 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): Year Ended December 31, 2019 2018 2017 (a) Packaging $ 5,932.2 $ 5,938.5 $ 5,312.3 Paper 964.3 1,002.0 1,051.8 Corporate and Other 67.8 74.1 80.8 Total revenue $ 6,964.3 $ 7,014.6 $ 6,444.9 _______________ (a) 2017 has not been adjusted under the modified retrospective method for Topic 606. Packaging Revenue Our containerboard mills produce linerboard and 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. 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 19, 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	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisitions	5 . Acquisitions Englander dZignPak On October 9, 2018, PCA acquired the assets of Englander dZignPak (“Englander”), a corrugated products manufacturer, for $56.3 million. The assets include two sheet plants located in Waco, Texas and Carrollton, Texas. Sales and total assets of the acquired company are not material to our overall sales and total assets. Operating results of the acquired assets subsequent to October 9, 2018 are included in our Packaging segment’s 2018 and 2019 operating results. The total purchase price has been allocated to the assets acquired and liabilities assumed based on fair values at the date of acquisition, of which $28.6 million was allocated to goodwill (which is deductible for tax purposes) and $14.1 million to intangible assets (to be amortized over a weighted average life of approximately 9.7 years), primarily customer relationships, in the Packaging segment. During the second quarter of 2019, we paid $1.4 million to the seller related to a final working capital adjustment. We recorded the adjustment as an increase to goodwill, which increased the purchase price to $57.7 million.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	6 . 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). Year Ended December 31, 2019 2018 2017 Numerator: Net income $ 696.4 $ 738.0 $ 668.6 Less: distributed and undistributed earnings allocated to participating securities (5.2 ) (5.7 ) (5.6 ) Net income attributable to common stockholders $ 691.2 $ 732.3 $ 663.0 Denominator: Weighted average common shares outstanding 93.8 93.7 93.5 Effect of dilutive securities 0.3 0.2 0.2 Diluted common shares outstanding 94.1 93.9 93.7 Basic income per common share $ 7.36 $ 7.82 $ 7.09 Diluted income per common share $ 7.34 $ 7.80 $ 7.07

Other (Expense) Income, Net

Other (Expense) Income, Net	12 Months Ended
	Dec. 31, 2019
Other Income And Expenses [Abstract]
Other (Expense) Income, Net	7 . Other (Expense) Income, Net The components of other (expense) income, net, were as follows (dollars in millions): Year Ended December 31, 2019 2018 2017 Asset disposals and write-offs (a) $ (25.0 ) $ (17.3 ) $ (10.5 ) Wallula mill restructuring (b) (0.7 ) (14.9 ) (23.1 ) Facilities closure and other costs (c) (0.3 ) (1.6 ) 5.9 Insurance deductible for property damage (d) — (0.5 ) — Acquisition and integration related costs (e) — (0.2 ) (0.8 ) DeRidder mill incident (f) — — 9.7 Hexacomb working capital adjustment (g) — — 2.3 Expiration of timberland repurchase option (h) — — 2.0 Other (6.7 ) (6.7 ) (3.9 ) Total $ (32.7 ) $ (41.2 ) $ (18.4 ) (a) For 2019, includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill. (b ) Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to produce virgin kraft linerboard. (c ) For 2019, includes charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility. For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes income primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, a paper administration facility, a corporate administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. ( d ) Includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities. (e ) Includes charges for acquisition and integration costs related to recent acquisitions. (f ) Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill. ( g ) Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico. ( h ) Includes a gain related to the expiration of a repurchase option corresponding to timberland previously sold.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	8 . Income Taxes The following is an analysis of the components of the consolidated income tax provision (dollars in millions): Year Ended December 31, 2019 2018 2017 Current income tax provision (benefit) - U.S. federal $ 123.2 $ 150.7 $ 209.3 State and local 37.0 42.9 34.9 Foreign 0.1 0.2 0.3 Total current provision for taxes 160.3 193.8 244.5 Deferred - U.S. federal 55.3 34.7 (90.2 ) State and local 5.0 4.0 5.7 Foreign — — — Total deferred provision (benefit) for taxes 60.3 38.7 (84.5 ) Total provision for taxes $ 220.6 $ 232.5 $ 160.0 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 revised 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. Generally accepted accounting principles required companies to record the impact of the Tax Act in their financial statements for the period during which the Tax Act became law, even if provisions of the Tax Act became effective at a future date. The SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118 ), Income Tax Accounting Implications of the Tax Cuts and Jobs Act In accordance with SAB 118, the Company recorded a final adjustment for the income tax effects of the Tax Act in the fourth quarter of 2018 totaling a net tax benefit of $2.0 million, primarily related to the re-measurement of our U.S. deferred tax assets and liabilities to the lower enacted corporate tax rate as a result of the release of additional regulatory guidance and the completion and filing of the 2017 federal and state income tax returns during calendar year 2018. The Company recorded provisional estimates of the income tax effects of the Tax Act in the fourth quarter of 2017 totaling a net tax benefit of $122.1 million, primarily related to the re-measurement of our U.S. deferred tax assets and liabilities to the lower enacted corporate tax rate for $128.0 million offset by a reduction in the domestic manufacturers deduction for $5.1 million, the Transition Tax and other current year tax reform impacts of $0.8 million The effective tax rate varies from the U.S. federal statutory tax rate principally due to the following (dollars in millions): 2019 2018 2017 Provision computed at U.S. federal statutory rate (a) $ 192.6 $ 203.8 $ 290.0 Federal tax reform — (2.0 ) (127.2 ) State and local taxes, net of federal benefit 35.7 36.9 24.0 Domestic manufacturers deduction (b) — — (21.1 ) Other (7.7 ) (6.2 ) (5.7 ) Total $ 220.6 $ 232.5 $ 160.0 (a) U.S. federal statutory rate of 21% (b) The domestic manufacturers deduction was eliminated after 2017 as a result of the Tax Cuts and Jobs Act. The following details the scheduled expiration dates of our tax effected net operating loss (NOL) and other tax carryforwards at December 31, 2019 (dollars in millions): 2020 Through 2029 2030 Through 2039 Indefinite Total U.S. federal NOLs $ 29.0 $ — $ — $ 29.0 State taxing jurisdiction NOLs 1.6 0.2 — 1.8 U.S. federal tax credit carryforwards 0.1 — — 0.1 U.S. federal and non-U.S. capital loss carryforwards 3.0 — 0.1 3.1 Total $ 33.7 $ 0.2 $ 0.1 $ 34.0 Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts for income tax purposes. Deferred income tax assets and liabilities at December 31 are summarized as follows (dollars in millions): December 31, 2019 2018 Deferred tax assets: Pension and postretirement benefits $ 90.7 $ 87.4 Lease obligations 59.2 — Employee benefits and compensation 35.5 37.7 Net operating loss carryforwards 30.8 34.4 Inventories 14.1 12.6 Restricted stock and performance units 11.2 10.2 Accrued liabilities 6.1 17.1 Capital loss and general business credit carryforwards 3.2 3.3 Derivatives 0.1 4.7 Gross deferred tax assets 250.9 207.4 Valuation allowance (c) (3.0 ) (3.1 ) Net deferred tax assets $ 247.9 $ 204.3 Deferred tax liabilities: Property, plant and equipment $ (459.1 ) $ (422.3 ) Goodwill and intangible assets (70.8 ) (67.2 ) Right-of-use assets (58.1 ) — Total deferred tax liabilities $ (588.0 ) $ (489.5 ) Net deferred tax liabilities (d) $ (340.1 ) $ (285.2 ) (c ) Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion of the deferred tax assets will not be realized. Both the 2019 and 2018 valuation allowance relates to capital losses. We do not expect to generate capital gains before the capital losses expire. If or when recognized, the tax benefits relating to the reversal of any or all of the valuation allowance would be recognized as a benefit to income tax expense. (d ) As of December 31, 2019, we did not recognize U.S. deferred income taxes on our cumulative total of undistributed foreign earnings for our foreign subsidiaries. We indefinitely reinvest our earnings in operations outside the United States. It is not practicable to determine the amount of unrecognized deferred tax liability on these undistributed earnings because the actual tax liability, if any, is dependent on circumstances existing when the repatriation occurs. Cash payments for federal, state, and foreign income taxes were $172.7 million, $140.8 million, and $298.7 million for the years ended December 31, 2019, 2018, and 2017, respectively. The following table summarizes the changes related to PCA’s gross unrecognized tax benefits excluding interest and penalties (dollars in millions): 2019 2018 2017 Balance as of January 1 $ (4.6 ) $ (4.8 ) $ (5.2 ) Increases related to prior years’ tax positions (0.1 ) (0.1 ) — Increases related to current year tax positions (0.4 ) (0.3 ) (0.4 ) Decreases related to prior years' tax positions — — — Settlements with taxing authorities — — — Expiration of the statute of limitations 0.3 0.6 0.8 Balance at December 31 $ (4.8 ) $ (4.6 ) $ (4.8 ) At December 31, 2019, PCA had recorded a $4.8 million gross reserve for unrecognized tax benefits, excluding interest and penalties. Of the total, $4.2 million (net of the federal benefit for state taxes) would impact the effective tax rate if recognized. PCA recognizes interest accrued related to unrecognized tax benefits and penalties as income tax expense. At December 31, 2019 and 2018, we had $1.2 million and $1.1 million, respectively, of interest and penalties recorded for unrecognized tax benefits. During the next 12 months, it is possible that PCA's unrecognized tax benefits related to state apportionment issues could decrease by approximately $3.1 million due to settlements with state taxing authorities. PCA is subject to income taxation in the United States, various state and local jurisdictions, Canada and Hong Kong. A federal examination of the 2016 tax year commenced in April 2019. The tax years 2016 - 2019 remain open to federal examination. The tax years 2015 - 2019 remain open to state examinations. Some foreign tax jurisdictions are open to examination for the 2009 tax year forward. Through the Boise acquisition, PCA recorded net operating losses and credit carryforwards from 2008 through 2011 and 2013 that are subject to examinations and adjustments for at least three years following the year in which utilized.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	9 . 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 December 31, 2019 and 2018, we had $863.5 million Changes in the carrying amount of our goodwill were as follows (dollars in millions): Total Packaging Paper Goodwill Balance at January 1, 2018 $ 828.0 $ 55.2 $ 883.2 Acquisitions (a)(b) 34.1 — 34.1 Balance at December 31, 2018 862.1 55.2 917.3 Acquisitions (c) 1.4 — 1.4 Balance at December 31, 2019 $ 863.5 $ 55.2 $ 918.7 (a) During 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container. (b ) In connection with the October 2018 acquisition of Englander, the Company recorded $28.6 million of goodwill in the Packaging segment in 2018. (c) During 2019, the Company recorded a $1.4 million adjustment to increase the goodwill balance for the Company’s October 2018 acquisition of Englander. See Note 5, Acquisitions, for more information. Intangible Assets Intangible assets are comprised of customer relationships and trademarks and trade names. The weighted average useful life, gross carrying amount, and accumulated amortization of our intangible assets were as follows (dollars in millions): As of December 31, 2019 As of December 31, 2018 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 (d)(e) 10.0 $ 503.8 $ 180.2 10.9 $ 504.6 $ 144.5 Trademarks and trade names (e) 9.5 34.8 20.6 10.1 34.8 18.3 Other (e) 2.1 4.3 3.3 3.0 4.4 2.7 Total intangible assets (excluding goodwill) 9.9 $ 542.9 $ 204.1 10.8 $ 543.7 $ 165.5 (d) During 2019, a corrugated products facility sold part of its operations which included existing inventory, certain production equipment, and customer relationships corresponding to the operations sold. As a result, the gross carrying amount for the customer relationships intangible asset was decreased by $0.7 million. (e ) In connection with the October 2018 acquisition of Englander, the Company recorded intangible assets of $13.2 million for customer relationships, $0.8 million for trade names, and $0.1 million for other intangibles. Amortization expense was $38.6 million, $40.5 million, and $35.7 million for the years ended December 31, 2019, 2018, and 2017, respectively. Estimated amortization expense of intangible assets over the next five years is expected to approximate $38.7 million (2020), $37.9 million (2021), $35.4 million Impairment Testing We test goodwill for impairment annually in the fourth quarter or sooner if events or changes in circumstances indicate that the carrying value of the asset may exceed fair value. Additionally, when we experience changes to our business or operating environment, we evaluate the remaining useful lives and recoverability of our finite-lived purchased intangible assets to determine whether any adjustments to the useful lives or impairment are necessary. We completed our test in the fourth quarter and there was no indication of goodwill or intangible asset impairment.

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2019
Accrued Liabilities Current And Noncurrent [Abstract]
Accrued Liabilities	10 . Accrued Liabilities The components of accrued liabilities were as follows (dollars in millions): December 31, 2019 2018 Compensation and benefits $ 124.5 $ 136.7 Customer volume discounts and rebates 27.9 25.2 Medical insurance and workers’ compensation 26.3 27.5 Franchise, property, sales and use taxes 15.3 13.4 Environmental liabilities and asset retirement obligations 5.6 5.0 Severance, retention, and relocation 3.5 2.2 Other 14.4 12.4 Total $ 217.5 $ 222.4

Debt

Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	11 . Debt At December 31, 2019 and 2018, our long-term debt and interest rates on that debt were as follows (dollars in millions): December 31, 2019 December 31, 2018 Amount Interest Rate Amount Interest rate Revolving Credit Facility, due August 2021 $ — — % $ — — % 2.45% Senior Notes, net of discount of $0.4 million as of December 31, 2018, due December 2020 — — % 499.6 2.45 % 3.90% Senior Notes, net of discount of $0.1 million as of December 31, 2018, due June 2022 — — % 399.9 3.90 % 4.50% Senior Notes, net of discount of $0.8 million and $1.0 million as of December 31, 2019 and 2018, respectively, due November 2023 699.2 4.50 % 699.0 4.50 % 3.65% Senior Notes, net of discount of $0.6 million and $0.7 million as of December 31, 2019 and 2018, respectively, due September 2024 399.4 3.65 % 399.3 3.65 % 3.40% Senior Notes, net of discount of $1.3 million and $1.5 million as of December 31, 2019 and 2018, respectively, due December 2027 498.7 3.40 % 498.5 3.40 % 3.00% Senior Notes, net of discount of $0.7 million as of December 31, 2019, due December 2029 499.3 3.00 % — — % 4.05% Senior Notes, net of discount of $3.5 million as of December 31, 2019, due December 2049 396.5 4.05 % — — % Total 2,493.1 3.77 % 2,496.3 3.64 % Less current portion — — % — — % Less unamortized debt issuance costs 16.3 12.6 Total long-term debt $ 2,476.8 3.77 % $ 2,483.7 3.64 % On November 21, 2019, the Company issued $500.0 million of 3.00% senior notes due 2029 and $400.0 million of 4.05% senior notes due 2049, through a registered public offering and notified the holders of its $500.0 million of 2.45% notes due December 15, 2020 and $400.0 million of 3.90% notes due June 15, 2022 that it would redeem those notes in December 2019. On December 6, 2019, PCA completed the redemption of the old 2.45% notes for $509.7 million, which included a redemption premium of $3.8 million and $5.8 million of accrued and unpaid interest. On December 23, 2019, PCA completed the redemption of the old 3.90% notes for $418.7 million, which included a redemption premium of $18.4 million and $0.3 million of accrued and unpaid interest. PCA used the proceeds of the offering of the new 3.00% and 4.05% notes and cash on hand to fund the redemptions and the $8.3 million of debt issuance costs. The debt issuance costs will be amortized to interest expense using the effective interest method over the terms of the notes. As of December 31, 2019, the details of our borrowings were as follows: • Senior Unsecured Credit Agreement . On October 18, 2013, we entered into a $1.65 billion senior unsecured credit facility. Loans bear interest at LIBOR plus a margin that is determined based upon our credit ratings. On August 29, 2016, we amended and restated this credit facility to include a new term loan facility (that was subsequently repaid in full in 2017) to finance an acquisition and to extend the maturity of the revolving credit facility to 2021. We have repaid all amounts borrowed under the credit facility, and the current facility now only includes a $350.0 million unsecured revolving credit facility with variable interest (LIBOR plus a margin) due August 2021. During 2019, we did not borrow under the Revolving Credit Facility. At December 31, 2019, we had $20.8 million of outstanding letters of credit that were considered outstanding on the revolving credit facility, resulting in $329.2 million of unused borrowing capacity. The outstanding letters of credit were primarily for workers compensation. We are required to pay commitment fees on the unused portions of the credit facility. • 3.90% Senior Notes. On June 26, 2012, we issued $400.0 million of 3.90% senior notes due June 15, 2022, through a registered public offering. The senior notes were repaid on December 23, 2019 with the proceeds received from the November 2019 note offering discussed above and cash on hand. • 4.50% Senior Notes . On October 22, 2013, we issued $700.0 million of 4.50% senior notes due November 1, 2023, through a registered public offering. • 3.65% Senior Notes. On September 5, 2014, we issued $400.0 million of 3.65% senior notes due September 15, 2024, through a registered public offering. • 2.45% Senior Notes. On December 13, 2017, we issued $500.0 million of 2.45% senior notes due December 15, 2020, through a registered public offering. The senior notes were repaid on December 6, 2019 with the proceeds received from the November 2019 note offering discussed above and cash on hand. • 3.40% Senior Notes. On December 13, 2017, we issued $500.0 million of 3.40% senior notes due December 15, 2027, through a registered public offering. • 3.00% Senior Notes . On November 21, 2019, we issued $500.0 million of 3.00% senior notes due December 15, 2029, through a registered public offering. • 4.05% Senior Notes . On November 21, 2019, we issued $400.0 million of 4.05% senior notes due December 15, 2049, through a registered public offering. The instruments governing our indebtedness contain financial and other covenants that limit the ability of PCA and its subsidiaries to enter into sale and leaseback transactions, incur liens, incur indebtedness at the subsidiary level, enter into certain transactions with affiliates, merge or consolidate with any other person or sell or otherwise dispose of all or substantially all of our assets. Our credit facility also requires us to comply with certain financial covenants, including maintaining a minimum interest coverage ratio and a maximum leverage ratio. A failure to comply with these restrictions could lead to an event of default, which could result in an acceleration of any outstanding indebtedness and/or prohibit us from drawing on the revolving credit facility. Such an acceleration may also constitute an event of default under the senior notes indenture. At December 31, 2019, we were in compliance with these covenants. At December 31, 2019, we have $2,493.1 million of fixed-rate senior notes outstanding. At December 31, 2019, the fair value of our fixed-rate debt was estimated to be $2,616.2 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), discussed further in Note 2, Summary of Significant Accounting Policies. Repayments, Interest, and Other In December 2019, we used the net proceeds from the November 2019 offering of the new 3.00% and 4.05% notes and cash on hand to redeem the 2.45% notes and 3.90% notes. We completed the redemption of the old 2.45% notes and 3.90% notes for $509.7 million and $418.7 million, respectively, which included redemption premiums and accrued and unpaid interest. In 2018, we used cash on hand to repay debt outstanding of $150.0 million under the 6.50% Senior Notes due March 15, 2018 at maturity. In 2017, we used the net proceeds from our 2.45% and 3.40% senior note offerings and other cash on hand to repay approximately $1.0 billion of borrowings outstanding under old term loan facilities. As of December 31, 2019, annual principal maturities for debt, excluding unamortized debt discount, are: none for 2020 through 2022; Interest payments paid in connection with the Company’s debt obligations for the years ended December 31, 2019, 2018, and 2017, were $114.0 million (including redemption premiums of $22.2 million), $97.0 million, and $96.3 million, respectively. Included in interest expense, net, are amortization of financing costs and amortization of treasury lock settlements. Amortization of treasury lock settlements was $18.2 million net loss in 2019 (including a $13.1 million write-off of the remaining balance for treasury locks related to the November 2019 debt refinancing), a $5.3 million net loss in 2018, and a $5.7 million net loss in 2017. Amortization of financing costs in 2019, 2018, and 2017 was $4.5 million (including a $1.8 million write-off of deferred debt issuance costs related to the November 2019 debt refinancing), $2.7 million, and $4.0 million (including a $1.8 million write-off of deferred debt issuance costs related to the December 2017 debt refinancing), respectively.

Cash, Cash Equivalents, and Mar

Cash, Cash Equivalents, and Marketable Debt Securities	12 Months Ended
	Dec. 31, 2019
Cash Cash Equivalents And Short Term Investments [Abstract]
Cash, Cash Equivalents, and Marketable Debt Securities	12 . Cash, Cash Equivalents, and Marketable Debt Securities The following table shows the Company’s cash and available-for-sale (AFS) debt securities by major asset category at December 31, 2019 (in millions): Adjusted Cost Basis Fair Value (c) Cash and Cash Equivalents Short-Term Marketable Debt Securities Long-Term Marketable Debt Securities Cash and cash equivalents $ 675.6 $ 675.6 $ 675.6 $ — $ — Level 1 (a) Money market funds 0.1 0.1 0.1 — — U.S. Treasury securities 27.1 27.1 3.1 11.5 12.5 Subtotal 27.2 27.2 3.2 11.5 12.5 Level 2 (b) Certificates of deposit 3.9 3.9 — 3.9 — Commercial paper 5.6 5.6 0.7 4.9 — U.S. government agency securities 7.0 7.0 — 3.0 4.0 Corporate debt securities 106.2 106.2 — 64.6 41.6 Subtotal 122.7 122.7 0.7 76.4 45.6 Total $ 825.5 $ 825.5 $ 679.5 $ 87.9 $ 58.1 (a) Valuations based on quoted prices for identical assets or liabilities in active markets. ( b ) Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data. ( c ) Unrealized gains and losses were insignificant as of December 31, 2019. Therefore, the fair value approximates the adjusted cost basis for each major asset category. As of December 31, 2018, we did not have any investments in marketable debt securities. For the year ended December 31, 2019, net realized gains and losses on the sales and maturities of certain marketable debt securities were insignificant. The Company invests in highly rated securities, with the primary objective of minimizing the potential risk of principal loss. The Company’s investment policy requires securities to be investment grade and limits the amount of credit exposure to any one issuer. The maturities of the Company’s long-term marketable debt securities generally range from one to two years. Fair values were determined for each individual marketable debt security in the investment portfolio. When evaluating a marketable debt security for other-than-temporary impairment, PCA reviews factors such as the duration and extent to which the fair value of the marketable debt security is less than its cost, the financial condition of the issuer and any changes thereto, the general market condition in which the issuer operates, and PCA's intent to sell or whether it will be more likely than not be required to sell, the marketable debt security before recovery of its amortized cost basis. As of December 31, 2019, we do not consider any of our marketable debt securities to be other-than-temporarily impaired. The market value of marketable debt securities with continuous unrealized losses as of December 31, 2019 was as follows (in millions): 2019 Continuous Unrealized Losses Less than 12 Months 12 Months or Greater Total Fair value of marketable debt securities $ 78.1 $ — $ 78.1 Unrealized losses $ — $ — $ —

Employee Benefit Plans and Othe

Employee Benefit Plans and Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans and Other Postretirement Benefits	13 . Employee Benefit Plans and Other Postretirement Benefits PCA has defined pension benefit plans for both salaried and hourly employees. The plans covering salaried employees are closed to new entrants with only certain current active participants still accruing benefits. The plans covering certain hourly employees are closed to new participants. We also have a Supplemental Executive Retirement Plan (SERP) and other nonqualified defined benefit pension plans that provide unfunded supplemental retirement benefits to certain of our executives and former executives. The SERP provides for incremental pension benefits in excess of those offered in our principal pension plans. Other Postretirement Benefits PCA provides postretirement medical benefits for certain retired salaried employees and postretirement medical and life insurance benefits for certain hourly employees. The plan covering salaried employees is closed to new participants. Obligations and Funded Status of Defined Benefit Pension and The funded status of PCA's plans change from year to year based on the plan asset investment return, contributions, benefit payments, the discount rate used to measure the liability, and expected participant longevity. The following table, which includes only company-sponsored defined benefit and other postretirement benefit plans, reconciles the beginning and ending balances of the projected benefit obligation and the fair value of plan assets. We recognize the unfunded status of these plans on the Consolidated Balance Sheets, and we recognize changes in funded status in the year changes occur through the Consolidated Statements of Comprehensive Income (dollars in millions): Pension Plans Postretirement Plans Year Ended December 31 Year Ended December 31 2019 2018 2019 2018 Change in Benefit Obligation Benefit obligation at beginning of period $ 1,204.9 $ 1,300.2 $ 14.6 $ 16.5 Service cost 24.5 25.0 0.3 0.3 Interest cost 47.0 42.4 0.5 0.5 Plan amendments 2.3 3.0 (0.3 ) (0.4 ) Actuarial (gain) loss (a) 188.6 (121.1 ) 0.2 (1.2 ) Participant contributions — — 1.1 1.1 Benefits paid (47.2 ) (44.6 ) (1.9 ) (2.2 ) Benefit obligation at plan year end $ 1,420.1 $ 1,204.9 $ 14.5 $ 14.6 Accumulated benefit obligation portion of above $ 1,374.4 $ 1,163.3 Change in Fair Value of Plan Assets Plan assets at fair value at beginning of period $ 873.2 $ 954.8 $ — $ — Actual return on plan assets 188.9 (59.9 ) — — Company contributions 58.9 22.9 0.8 1.1 Participant contributions — — 1.1 1.1 Benefits paid (47.2 ) (44.6 ) (1.9 ) (2.2 ) Fair value of plan assets at plan year end $ 1,073.8 $ 873.2 $ — $ — Underfunded status $ (346.3 ) $ (331.7 ) $ (14.5 ) $ (14.6 ) Amounts Recognized on Consolidated Balance Sheets Current liabilities (1.4 ) (1.4 ) (0.7 ) (0.8 ) Noncurrent liabilities (344.9 ) (330.3 ) (13.8 ) (13.8 ) Accrued obligation recognized at December 31 $ (346.3 ) $ (331.7 ) $ (14.5 ) $ (14.6 ) Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax) Prior service cost (credit) $ 24.7 $ 28.7 $ (5.3 ) $ (5.4 ) Actuarial loss (gain) 239.2 194.6 (4.4 ) (5.0 ) Total $ 263.9 $ 223.3 $ (9.7 ) $ (10.4 ) (a) The actuarial loss in 2019 was due primarily to a decrease in the weighted average discount rate used to estimate pension benefit obligations. The actuarial gain in 2018 was due primarily to an increase in the weighted average discount rate used to estimate our pension benefit obligations. Components of Net Periodic Benefit Cost and Other Comprehensive (Income) Loss The components of net periodic benefit cost and other comprehensive (income) loss (pretax) were as follows (dollars in millions): Pension Plans Postretirement Plans Year Ended December 31, Year Ended December 31, 2019 2018 2017 2019 2018 2017 Service cost $ 24.5 $ 25.0 $ 23.7 $ 0.3 $ 0.3 $ 0.3 Interest cost 47.0 42.4 41.6 0.5 0.5 0.6 Expected return on plan assets (52.1 ) (56.7 ) (53.9 ) — — — Net amortization of unrecognized amounts Prior service cost (credit) 6.3 6.9 5.8 (0.3 ) (0.3 ) (0.2 ) Actuarial loss (gain) 7.0 9.4 7.6 (0.4 ) (0.2 ) (0.1 ) Net periodic benefit cost $ 32.7 $ 27.0 $ 24.8 $ 0.1 $ 0.3 $ 0.6 Changes in plan assets and benefit obligations recognized in other comprehensive (income) loss Actuarial net loss (gain) $ 51.8 $ (4.6 ) $ 32.2 $ 0.2 $ (1.2 ) $ (2.2 ) Prior service cost (credit) 2.3 3.0 17.4 (0.3 ) (0.3 ) (0.6 ) Amortization of prior service cost (credit) (6.3 ) (6.9 ) (5.8 ) 0.3 0.3 0.2 Amortization of actuarial loss (gain) (7.0 ) (9.4 ) (7.6 ) 0.4 0.2 0.1 Total recognized in other comprehensive loss (income) (b) $ 40.8 $ (17.9 ) $ 36.2 $ 0.6 $ (1.0 ) $ (2.5 ) Total recognized in net periodic benefit cost and other comprehensive loss (income) (pre-tax) $ 73.5 $ 9.2 $ 61.0 $ 0.7 $ (0.7 ) $ (1.9 ) (b ) Accumulated losses in excess of 10% of the greater of the projected benefit obligation or the market-related value of assets will be recognized on a straight-line basis over the average remaining service period of active employees in PCA plans (which is between seven and ten years) and over the average remaining lifetime of inactive participants of Boise plans (which is between 24 and 27 years), to the extent that losses are not offset by gains in subsequent years. The estimated net loss and prior service cost that will be amortized from “Accumulated other comprehensive loss” into net periodic benefit in 2020 is $14.3 million. The accumulated benefit obligations for the plans with obligations in excess of plan assets is $1.3 billion. Assumptions The following table presents the assumptions used in the measurement of our benefits obligations: Pension Plans Postretirement Plans December 31, December 31, 2019 2018 2017 2019 2018 2017 Weighted-Average Assumptions Used to Determine Benefit Obligations at December 31 Discount rate 3.25% 4.31% 3.66% 3.18% 4.21% 3.55% Rate of compensation increase 4.00% 4.00% 4.00% N/A N/A N/A Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost for the Years Ended December 31 Discount rate 4.31% 3.66% 4.24% 4.21% 3.57% 3.92% Expected return on plan assets 6.06% 6.06% 6.55% N/A N/A N/A Rate of compensation increase 4.00% 4.00% 4.00% N/A N/A N/A Discount Rate Assumption. The discount rate reflects the current rate at which the pension obligations could be settled on the measurement date: December 31. The discount rate assumption used to calculate the present value of pension and postretirement benefit obligations reflects the rates available on high-quality, fixed-income debt instruments at December 31. In all periods, the bonds included in the models reflect anticipated investments that would be made to match the expected monthly benefit payments over time. The plans' projected cash flows were duration-matched to these models to develop an appropriate discount rate. Asset Return Assumption. The expected return on plan assets reflects the expected long-term rates of return for the categories of investments currently held in the plans as well as anticipated returns for additional contributions made in the future. The expected long-term rate of return is adjusted when there are fundamental changes in expected returns on the plan investments. The weighted-average expected return on plan assets we will use in our calculation of 2020 net periodic pension benefit cost is 5.29%. Rate of Compensation Increase. The rate of compensation increase is determined by PCA based upon annual reviews. The compensation increase assumption is not applicable for all plans as many of our pension plans are frozen and not accruing benefits. Health Care Cost Trend Rate Assumptions. PCA assumed health care cost trend rates for its postretirement benefits plans were as follows: 2019 2018 2017 Health care cost trend rate assumed for next year 7.09% 7.24% 7.57% Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50% 4.44% 4.44% Year that the rate reaches the ultimate trend rate 2029 2028 2027 Postretirement Health Care Plan Assumptions. For postretirement health care plan accounting, PCA reviews external data and its own historical trends for health care costs to determine the health care cost trend rate assumption. A one-percentage point change in assumed health care cost trend rates would have the following effects on the 2019 postretirement benefit obligation and the 2018 net postretirement benefit cost (dollars in millions): 1-Percentage Point Increase 1-Percentage Point Decrease Effect on postretirement benefit obligation $ 0.5 $ (0.5 ) Effect on net postretirement benefit cost 0.1 — Investment Policies and Strategies PCA has retained the services of professional advisors to oversee pension investments and provide recommendations regarding investment strategy. PCA’s overall strategy and related apportionments between equity and debt securities may change from time to time based on market conditions, external economic factors, and the funded status of the plans. The general investment objective for all of our plan assets is to optimize growth of the pension plan trust assets, while minimizing the risk of significant losses to enable the plans to satisfy their benefit payment obligations over time. The objectives take into account the long-term nature of the benefit obligations, the liquidity needs of the plans, and the expected risk/return trade-offs of the asset classes in which the plans may choose to invest. Assets of our pension plans were invested in the following classes of securities at December 31, 2019 and 2018: Percentage of Fair Value at December 31, 2019 2018 Fixed income securities 50 % 53 % International equity securities 27 % 27 % Domestic equity securities 22 % 18 % Other 1 % 2 % At December 31, 2019, the targeted investment allocations differed between the acquired Boise plans and PCA’s historical plans based on funded status. At December 31, 2019, PCA’s historical plans, which comprised $498.8 million of the total fair value of plan assets, targeted 52% in fixed income securities, 47% invested in equities, and and equities , and 2 % in other . Our retirement committee reviews the investment allocations for reasonableness at a minimum, semi-annually. Investment securities, in general, are exposed to various risks, such as interest rate, credit, and overall market volatility risk, all of which are subject to change. Due to the level of risk associated with some investment securities, it is reasonably possible that changes in the values of investment securities will occur in the near term, and such changes could materially affect the reported amounts. Fair Value Measurements of Plan Assets The following tables set forth, by level within the fair value hierarchy, discussed in Note 2, Summary of Significant Accounting Policies, the pension plan assets, by major asset category, at fair value at December 31, 2019 and 2018 (dollars in millions): Fair Value Measurements at December 31, 2019 Asset Category Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value (NAV) (a) Total Cash and short-term investments $ — $ 14.9 $ — $ — $ 14.9 Common/collective trust funds: International equities 163.0 20.8 — 102.3 286.1 Domestic equities — 240.5 — — 240.5 Corporate and government bonds: Fixed income 140.4 154.6 — — 295.0 Government bonds and agencies — 160.7 — — 160.7 Corporate bonds — 70.6 — — 70.6 Municipal bonds — 5.8 — — 5.8 Private equity securities (b) — — 2.6 — 2.6 Total securities at fair value $ 303.4 $ 667.9 $ 2.6 $ 102.3 $ 1,076.2 Accrued expenses and receivables (2.4 ) Total fair value of plan assets $ 1,073.8 Fair Value Measurements at December 31, 2018 Asset Category Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value (NAV) (a) Total Cash and short-term investments $ 0.4 $ 11.6 $ — $ — $ 12.0 Common/collective trust funds: Domestic equities — 154.5 — — 154.5 International equities 136.9 17.8 — 84.1 238.8 Corporate and government bonds: Government bonds 155.0 9.4 — 164.4 Corporate bonds — 64.4 — 64.4 Fixed income 95.7 138.8 — — 234.5 Private equity securities (b) — — 3.3 — 3.3 Total securities at fair value $ 388.0 $ 396.5 $ 3.3 $ 84.1 $ 871.9 Receivables and accrued expenses 1.3 Total fair value of plan assets $ 873.2 (a) In accordance with ASC 820, Fair Value Measurement ( b ) Investments in this category are invested in the Pantheon Global Secondary Fund IV, LP. The fund specializes in investments in the private equity secondary market and occasionally directly in private companies to maximize capital growth. Fund investments are carried at fair value as determined quarterly using the market approach to estimate the fair value of private investments. The market approach utilizes prices and other relevant information generated by market transactions, type of security, size of the position, degree of liquidity, restrictions on the disposition, latest round of financing data, current financial position, and operating results, among other factors. In circumstances where fair values are not provided with respect to any of the company's fund investments, the investment advisor will seek to determine the fair value of such investments based on information provided by the general partners or managers of such funds or from other sources. Audited financial statements are provided by fund management annually. Notwithstanding the above, the variety of valuation bases adopted and quality of management data of the ultimate underlying investee companies means that there are inherent difficulties in determining the value of the investments. Amounts realized on the sale of these investments may differ from the calculated values. Boise had originally committed to a $ 15.0 million investment, with $ 5.0 million of the commitment unfunded at December 31, 2019 . The following table sets forth a summary of changes in the fair value of the pension plans' Level 3 assets for the year ended December 31, 2019 (dollars in millions): 2019 Balance, beginning of year $ 3.3 Acquisitions — Purchases — Sales (0.7 ) Unrealized gain — Balance, end of year $ 2.6 Funding and Cash Flows 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 discretionary contributions based on the funded status of the plans, tax deductibility, income from operations, and other factors. In 2019, 2018, and 2017, we made contributions of $57.9 million, $21.8 million, and $42.1 million, respectively, to our qualified pension plans. We expect to contribute at least the estimated required minimum contributions to our qualified pension plans of approximately $19.8 million in 2020. The following are estimated benefit payments to be paid to current plan participants by year (dollars in millions). Qualified pension benefit payments are paid from plan assets, while nonqualified pension benefit payments are paid by the Company. Pension Plans Postretirement Plans 2020 $ 52.7 $ 0.7 2021 56.7 0.7 2022 60.4 0.7 2023 64.1 0.7 2024 - 2029 442.5 4.5 Defined Contribution Plans Some of our employees participate in contributory defined contribution savings plans, available to most of our salaried and hourly employees. The defined contribution plans permit participants to make contributions by salary reduction pursuant to Section 401(k) of the Code. PCA made employer-matching contributions of $48.9 million, $45.6 million, and $42.8 million in 2019, 2018, and 2017, respectively. All company-matching contributions to all employees were made in cash. We expense employer matching contributions and charge dividends on shares held by the ESOP to retained earnings. Shares of company stock held by the ESOP are included in basic shares for earnings-per-share computations. At December 31, 2019 and 2018, the ESOP held 1.5 million and 1.9 million shares of Company stock, respectively. Certain salaried and hourly employees that are not participating in a PCA sponsored defined benefit pension plan receive a service-related company retirement contribution to their defined contribution plan account in addition to any employer matching contribution. This contribution increases with years of service and ranges from 3% to 5% of base pay. We contributed $27.8 million, $24.5 million, and $22.4 million for this retirement contribution during the years ended December 31, 2019, 2018, and 2017, respectively. Deferred Compensation Plans Key managers can elect to participate in a deferred compensation plan. The deferred compensation plan is unfunded; therefore, benefits are paid from our general assets. At December 31, 2019 and 2018, we had $17.4 million and $14.2 million, respectively, of liabilities attributable to participation in our deferred compensation plan on our Consolidated Balance Sheets.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	1 4 . Asset Retirement Obligations Our asset retirement obligations relate predominantly to landfill closure, wastewater treatment pond dredging, closed-site monitoring costs, and certain leasehold improvements. In accordance with ASC 410, Asset Retirement and Environmental Obligations, The following table describes changes to the asset retirement obligation liability (dollars in millions): Year Ended December 31, 2019 2018 Asset retirement obligation at beginning of period $ 30.0 $ 35.1 Accretion expense 1.5 1.6 Payments (3.5 ) (7.9 ) Revisions in estimated cash flows (0.2 ) 1.2 Asset retirement obligation at end of period $ 27.8 $ 30.0 We have additional asset retirement obligations with indeterminate settlement dates. The fair value of these asset retirement obligations cannot be estimated due to the lack of sufficient information to estimate the settlement dates of the obligations. These asset retirement obligations include, for example, (i) removal and disposal of potentially hazardous materials related to equipment and/or an operating facility if the equipment and/or facilities were to undergo major maintenance, renovation, or demolition and (ii) storage sites or owned facilities for which removal and/or disposal of chemicals and other related materials are required if the operating facility is closed. We will recognize a liability in the period in which sufficient information becomes available to reasonably estimate the fair value of these obligations.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share Based Compensation [Abstract]
Share-Based Compensation	15 . Share-Based Compensation The Company has a long-term equity incentive plan, which allows for grants of stock options, stock appreciation rights, restricted stock, and performance awards 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 shares of common stock for grant over the life of the plan. As of December 31, 2019, 0.4 million shares remained available for future issuance under the plan. Forfeitures are added back to the pool of shares of common stock available to be granted at a future date. Restricted Stock Restricted stock awards granted to officers and employees generally vest at the end of a four-year 2019 2018 2017 Shares Weighted Average Grant- Date Fair Value Shares Weighted Average Grant- Date Fair Value Shares Weighted Average Grant- Date Fair Value Restricted stock at January 1 743,591 $ 86.90 739,732 $ 77.23 786,079 $ 63.44 Granted 199,499 95.48 173,144 114.63 173,199 107.57 Vested (a) (212,809 ) 68.59 (165,547 ) 72.84 (213,992 ) 51.37 Forfeitures (13,329 ) 98.86 (3,738 ) 78.66 (5,554 ) 69.03 Restricted stock at December 31 716,952 $ 94.50 743,591 $ 86.90 739,732 $ 77.23 (a) The total fair value of awards upon vesting for the years ended December 31, 2019, 2018, and 2017 was $19.9 million, . Performance Units Performance unit awards granted to certain key employees 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. ROIC performance unit awards vest four years after the grant date, while TSR performance unit awards vest approximately three years after the grant date. Both ROIC and TSR performance units are paid out entirely in shares of the Company’s common stock. A summary of the Company’s performance unit activity follows: 2019 2018 2017 Units Weighted Average Grant- Date Fair Value Units Weighted Average Grant- Date Fair Value Units Weighted Average Grant- Date Fair Value Performance units at January 1 266,704 $ 90.01 226,558 $ 77.07 232,088 $ 62.68 Granted 115,608 96.98 83,515 115.35 53,070 108.19 Vested (a) (59,165 ) 67.84 (43,369 ) 71.19 (58,600 ) 56.08 Performance units at December 31 323,147 $ 96.56 266,704 $ 90.01 226,558 $ 77.07 (a) The total fair value of awards upon vesting for the years ended December 31, 2019, 2018, and 2017 was $5.5 million, $5.4 million, and $7.5 million, respectively. Upon vesting of the awards in 2019, 2018, and 2017, PCA issued 59,165 shares, 46,876 shares, and 67,391 shares, respectively. For 2019, 2018, and 2017, these amounts included 6,063 shares, 3,507 shares, and 8,791 shares, respectively, for dividends accrued during the vesting period. Compensation Expense Our share-based compensation expense is recorded in “Cost of sales” and “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): Year Ended December 31, 2019 2018 2017 Restricted stock $ 22.6 $ 18.6 $ 15.0 Performance units 7.8 4.9 5.6 Impact on income before income taxes 30.4 23.5 20.6 Income tax benefit (7.6 ) (5.9 ) (7.9 ) Impact on net income $ 22.8 $ 17.6 $ 12.7 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. For performance unit awards made in 2019 and 2018, in terms of grant date value, 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 was as follows (dollars in millions): December 31, 2019 Unrecognized Compensation Expense Remaining Weighted Average Recognition Period (in years) Restricted stock $ 27.2 3.1 Performance units 17.2 2.4 Total unrecognized share-based compensation expense $ 44.4 2.8 We evaluate share-based compensation expense on a quarterly basis based on our estimate of expected forfeitures, review of recent forfeiture activity, and expected future turnover. We recognize the effect of adjusting the forfeiture rate for all expense amortization in the period that we change the forfeiture estimate. The effect of forfeiture adjustments was insignificant in all periods presented.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2019
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	16 . Derivative Instruments and Hedging Activities Hedging Strategy When appropriate, we use derivatives as a risk management tool to mitigate the potential impact of certain market risks. The primary risks managed by using derivative financial instruments are interest rate risks. We do not enter into derivative financial instruments for trading or speculative purposes. Interest Rate Risk The Company has used treasury lock derivative instruments to manage interest costs and the risk associated with changing interest rates. In connection with contemplated issuances of ten-year debt securities, PCA entered into interest rate protection agreements with counterparties in 2008, 2010, and 2011 to protect against increases in the ten-year U.S. Treasury Note rate. These treasury rates served as references in determining the interest rates applicable to the debt securities the Company issued in March 2008 and June 2012. As a result of changes in the interest rates on those treasury securities between the time PCA entered into the derivative agreements and the time PCA priced and issued the debt securities, the Company: (1) made a payment of $4.4 million to the counterparty upon settlement of the 2008 interest rate protection agreement on March 25, 2008; (2) received a payment of $9.9 million from the counterparties upon settlement of the 2010 interest rate protection agreements on February 4, 2011; and (3) made a payment of $65.5 million to the counterparty upon settlement of the 2011 interest rate protection agreement on June 26, 2012. The Company recorded the effective portion of the settlements in accumulated OCI, and these amounts were amortized over the terms of the respective notes. During the fourth quarter of 2019, the Company recorded a charge of $13.1 million in interest expense from the write-off of the remaining treasury lock balance due to the redemption of the 3.90% notes on December 23, 2019. Derivative Instruments The impact of derivative instruments on the consolidated statements of income and accumulated OCI was as follows (dollars in millions): Net Loss Recognized in Accumulated OCI (Effective Portion) December 31, 2019 2018 Treasury locks, net of tax $ — $ (10.2 ) Loss Reclassified from Accumulated OCI into Income (Effective Portion) Year Ended December 31, 2019 2018 2017 Amortization of treasury locks (included in interest expense, net) $ (18.2 ) $ (5.3 ) $ (5.7 ) As a result of our November 2019 debt refinancing and redemption of the 3.90% notes due June 15, 2022, the Company accelerated the amortization of the remaining treasury lock balance of $13.1 million ($6.5 million after tax) during the fourth quarter of 2019. The after tax amount includes $3.2 million of income tax benefit from the stranded tax effects in accumulated OCI related to the write-off of the remaining treasury lock balance.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity	17 . Stockholders' Equity Dividends During the year ended December 31, 2019, we paid $298.7 million of dividends to shareholders. On December 10, 2019, PCA's Board of Directors approved a regular quarterly cash dividend of $0.79 per share of common stock, which was paid on January 15, 2020 to shareholders of record as of December 20, 2019. 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 an annual payout of $3.16 per share. The first quarterly dividend of $0.79 per share was paid on July 13, 2018 to shareholders of record as of June 15, 2018. Share Repurchase Program 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 twelve months ended December 31, 2019 and 2018. All shares repurchased in prior years have been retired. At December 31, 2019, $193.0 million Accumulated Other Comprehensive Income (Loss) Changes in AOCI, net of taxes, by component 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 December 31, 2018 $ (0.4 ) $ (10.2 ) $ (0.3 ) $ (127.9 ) $ (138.8 ) Other comprehensive income before reclassifications — — — (40.5 ) (40.5 ) Amounts reclassified from AOCI — 10.2 0.1 9.5 19.8 Net current-period other comprehensive income — 10.2 0.1 (31.0 ) (20.7 ) Balance at December 31, 2019 $ (0.4 ) $ — $ (0.2 ) $ (158.9 ) $ (159.5 ) The following table presents information about reclassifications out of AOCI (dollars in millions). Amounts in parentheses indicate expenses in the Consolidated Statements of Income. Amounts Reclassified from AOCI Year Ended December 31, Details about AOCI Components 2019 2018 Unrealized loss on treasury locks, net (a) $ (18.1 ) $ (5.3 ) 7.9 1.3 Tax benefit $ (10.2 ) $ (4.0 ) Net of tax Unfunded employee benefit obligations (b) Amortization of prior service costs $ (6.0 ) $ (6.6 ) Amortization of actuarial gains / (losses) (6.7 ) (9.2 ) (12.7 ) (15.8 ) Total before tax 3.2 4.0 Tax benefit $ (9.5 ) $ (11.8 ) Net of tax (a) This AOCI component is included in interest expense, net. The remaining balances of the treasury locks were written off as a result of the Company’s November 2019 debt refinancing. For a discussion of treasury lock derivative instrument activity, see Note 16, Derivative Instruments and Hedging Activities, for additional information. (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	12 Months Ended
	Dec. 31, 2019
Risks And Uncertainties [Abstract]
Concentration of Risk	18 . Concentrations of Risk Our Paper segment has had 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 represented 7% of our total Company sales for both 2019 and 2018 and about 50% and 47% of our Paper segment sales revenue for those periods, respectively. At December 31, 2019 and 2018, we had $76.2 million and $66.7 million of accounts receivable due from Office Depot, respectively, which represents 9% and 7% of our total Company receivables, respectively. In 2019, sales to Office Depot represented about 50% 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. Labor At December 31, 2019, we had approximately 15,500 employees and approximately 45%

Transactions With Related Parti

Transactions With Related Parties	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Transactions With Related Parties	19 . 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 both $3.9 million at December 31, 2019 and $2.7 million at December 31, 2018. For 2019, 2018, and 2017, we recorded $81.7 million, $83.1 million, and $86.4 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”. Fiber purchases from related parties were $16.8 million

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Information	20 . 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 paper grades at the Wallula, Washington mill and converted the No. 3 machine at the mill to produce virgin kraft linerboard. Before May 2018, operating results for the Wallula mill were included in the Paper segment. After May 2018, operating results for the Wallula mill are primarily included in the Packaging segment. Packaging. We manufacture and sell a wide variety of containerboard and corrugated packaging products, including conventional shipping containers used to protect and transport manufactured goods, multi-color boxes and displays with strong visual appeal that help to merchandise the packaged product in retail locations. In addition, we are a large producer of packaging for meat, fresh fruit and vegetables, processed food, beverages, and other industrial and consumer products. Paper. We manufacture and sell a range of communication-based papers. Our papers can be manufactured as either commodity papers or specialty papers with specialized or custom features, such as colors, coatings, high brightness, or recycled content. Corporate and Other. Our Corporate and Other segment includes corporate support staff services and related assets and liabilities, and foreign exchange gains and losses. This segment also includes transportation assets, such as rail cars and trucks, which we use to transport our products from some of our manufacturing sites and assets related to LTP. See Note 19, Transactions with Related Parties, for more information related to LTP. Sales in this segment relate primarily to LTP and our rail and truck business. We provide transportation services not only to our own facilities but also, on a limited basis, to third parties when geographic proximity and logistics are favorable. Rail cars and trucks are generally leased. Each segments' profits and losses are measured on operating profits before interest expense, net and other and income taxes. For many of these allocated expenses, the related assets and liabilities remain in the Corporate and Other segment. Segment sales to external customers by product line were as follows (dollars in millions): Year Ended December 31, 2019 2018 2017 Packaging $ 5,932.2 $ 5,938.5 $ 5,312.3 Paper 964.3 1,002.0 1,051.8 Corporate and Other 67.8 74.1 80.8 $ 6,964.3 $ 7,014.6 $ 6,444.9 Sales to foreign unaffiliated customers during the years ended December 31, 2019, 2018, and 2017 were An analysis of operations by reportable segment is as follows (dollars in millions): Sales, net Operating Depreciation, Year Ended December 31, 2019 Trade Inter- segment Total Income (Loss) Amortization, and Depletion Capital Expenditures (l) Assets Packaging $ 5,905.1 $ 27.1 $ 5,932.2 $ 963.4 (b) $ 342.8 $ 367.4 $ 5,491.5 Paper 964.3 — 964.3 175.4 (c) 37.7 23.8 791.4 Corporate and Other 94.9 133.1 228.0 (85.1 ) 7.0 8.3 952.9 Intersegment eliminations — (160.2 ) (160.2 ) — — — — $ 6,964.3 $ — $ 6,964.3 1,053.7 $ 387.5 $ 399.5 $ 7,235.8 Non-operating pension expense (7.9 ) Interest expense, net (128.8 ) (d) Income before taxes $ 917.0 Sales, net Operating Depreciation, Year Ended December 31, 2018 Trade Inter- segment Total Income (Loss) Amortization, and Depletion Capital Expenditures (l) Assets Packaging $ 5,912.3 $ 26.2 $ 5,938.5 $ 1,045.4 (e) $ 342.0 $ 504.0 $ 5,347.0 Paper 1,002.0 — 1,002.0 97.7 (f) 62.0 12.6 760.1 Corporate and Other 100.3 129.4 229.7 (75.4 ) (g) 6.9 34.8 462.6 Intersegment eliminations — (155.6 ) (155.6 ) — — — — $ 7,014.6 $ — $ 7,014.6 1,067.7 $ 410.9 $ 551.4 $ 6,569.7 Non-operating pension expense (2.1 ) Interest expense, net (95.1 ) Income before taxes $ 970.5 Sales, net Operating Depreciation, Year Ended December 31, 2017 Trade Inter- segment Total Income (Loss) (a) Amortization, and Depletion Capital Expenditures (l) Assets Packaging $ 5,288.6 $ 23.7 $ 5,312.3 $ 950.3 (h) $ 317.5 $ 305.1 $ 4,933.6 Paper 1,051.8 — 1,051.8 54.0 (i) 67.6 22.6 945.2 Corporate and Other 104.5 124.7 229.2 (71.8 ) (j) 6.3 15.3 318.7 Intersegment eliminations — (148.4 ) (148.4 ) — — — — $ 6,444.9 $ — $ 6,444.9 932.5 $ 391.4 $ 343.0 $ 6,197.5 Non-operating pension expense (1.3 ) Interest expense, net (102.6 ) (k) Income before taxes $ 828.6 (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 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) Year Ended December 31, 2017 As Reported Non-Operating Pension Adjustment Year Ended December 31, 2017 Adjusted Packaging $ 943.7 $ 6.6 $ 950.3 Paper 61.5 (7.5 ) 54.0 Corporate (74.0 ) 2.2 (71.8 ) Income from operations 931.2 1.3 932.5 Non-operating pension expense — (1.3 ) (1.3 ) Interest expense, net (102.6 ) — (102.6 ) Income before taxes $ 828.6 $ — $ 828.6 (b) Includes the following: o $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill. o $0.8 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility (c) Includes $0.2 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. (d) Includes $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs. (e) Includes the following: o $12.3 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $1.6 million of charges consisting of closure costs related to corrugated products facilities. o $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. o $0.2 million of charges for acquisition and integration costs related to recent acquisitions. (f) second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. (g) (h) o $7.2 million of income, net, primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. o $1.7 million of charges for acquisition and integration costs related to recent acquisitions. o $2.0 million gain related to the expiration of a repurchase option corresponding to timberland previously sold. o $1.6 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico. o $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. (i) (j) (k) Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing. (l) Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

Commitments, Guarantees, Indemn

Commitments, Guarantees, Indemnifications, and Legal Proceedings	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments, Guarantees, Indemnifications, and Legal Proceedings	21 . 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 (discussed in Note 11, Debt), lease obligations (discussed in Note 3, Leases), capital commitments, purchase commitments for goods and services, and legal proceedings (discussed below). Capital Commitments The Company had capital commitments of approximately $212.6 million and $112.8 million as of December 31, 2019 and 2018, respectively, in connection with the expansion and replacement of existing facilities and equipment. Purchase Commitments In the table below, we set forth our enforceable and legally binding purchase obligations as of December 31, 2019. Some of the amounts are based on management's estimates and assumptions about these obligations, including their duration, the possibility of renewal, anticipated actions by third parties, and other factors. Because these estimates and assumptions are necessarily subjective, our actual payments may vary from those reflected in the table. Purchase orders made in the ordinary course of business are excluded below. Any amounts for which we are liable under purchase orders are reflected on the Consolidated Balance Sheets as accounts payable and accrued liabilities. These obligations relate to various purchase agreements for items such as minimum amounts of energy and fiber purchases over periods ranging from one year to 31 years. Total purchase commitments were as follows (dollars in millions): 2020 $ 51.9 2021 47.4 2022 43.0 2023 42.8 2024 24.6 Thereafter 109.3 Total $ 319.0 The Company purchased a total of $315.0 million, $341.9 million, and $339.1 million during the years ended December 31, 2019, 2018, and 2017, respectively, under these purchase agreements. Environmental Matters On August 8, 2019, the EPA issued a notice of violation (NOV) alleging violations of the Clean Air Act, resulting from an inspection at our Wallula, Washington mill in September 2018. PCA denies the violations set forth in the NOV and has requested that the EPA’s Office of Air Quality Planning and Standards provide an applicability determination to clarify that the relevant operations of PCA have not violated the regulations at issue in the NOV. While we cannot predict with certainty the ultimate resolution of this matter, we believe that we have a meritorious position that our operations have not violated the Clean Air Act, that we have taken appropriate action to address the matters raised by the EPA in the NOV, and that this matter will not result in a material adverse effect on our financial condition, results of operations, or cash flows. The potential costs for various environmental matters are uncertain due to such factors as the unknown magnitude of possible cleanup costs, the complexity and evolving nature of governmental laws and regulations and their interpretations, and the timing, varying costs and effectiveness of alternative cleanup technologies. From 2006 through 2019, there were no significant environmental remediation costs at PCA's mills and corrugated plants. Guarantees and Indemnifications We provide guarantees, indemnifications, and other assurances to third parties in the normal course of our business. These include tort indemnifications, environmental assurances, and representations and warranties in commercial agreements. At December 31, 2019, 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. A ll 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 publishing its investigation findings 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.

Quarterly Results of Operations

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations (Unaudited)	22 . Quarterly Results of Operations (unaudited, dollars in millions, except per-share and stock price information) 2019: First (a) Second Third (b) Fourth (c) Total Net sales $ 1,733.7 $ 1,759.9 $ 1,750.7 $ 1,720.0 $ 6,964.3 Gross profit 421.4 427.9 411.4 383.3 1,644.0 Income from operations 275.4 280.4 262.8 235.1 1,053.7 Net income 186.8 193.6 179.8 136.2 696.4 Basic earnings per share 1.98 2.05 1.90 1.44 7.36 Diluted earnings per share 1.97 2.04 1.89 1.43 7.34 Stock price - high 101.84 103.80 109.37 114.78 114.78 Stock price - low 81.87 87.85 96.30 100.54 81.87 2018: First (d) Second (e) Third (f) Fourth (g) Total Net sales $ 1,690.6 $ 1,767.5 $ 1,809.9 $ 1,746.6 $ 7,014.6 Gross profit 356.1 420.6 443.2 425.4 1,645.3 Income from operations 212.9 269.6 298.5 286.7 1,067.7 Net income 140.1 186.6 206.7 204.6 738.0 Basic earnings per share 1.48 1.98 2.19 2.17 7.82 Diluted earnings per share 1.48 1.97 2.18 2.16 7.80 Stock price - high 131.13 124.70 118.88 110.62 131.13 Stock price - low 109.04 107.96 107.39 77.90 77.90 Note: The sum of the quarters may not equal the total of the respective year's earnings per share on either a basic or diluted basis due to changes in the weighted average shares outstanding throughout the year. (a) Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share). (b) Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share). (c) Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share). (d ) Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share). (e ) Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share). (f ) Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share). (g ) Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. These estimates and assumptions are based on management's best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment. We adjust such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in these estimates will be reflected in the consolidated financial statements in future periods.
Revenue Recognition	Revenue Recognition In accordance with ASU 2014-09 (Topic 606): Revenue from Contracts with Customers
Planned Major Maintenance Costs	Planned Major Maintenance Costs The Company accounts for its planned major maintenance activities in accordance with ASC 360, Property, Plant, and Equipment
Share-Based Compensation	Share-Based Compensation We recognize compensation expense for awards granted under the PCA long-term equity incentive plans based on the fair value on the grant date. We recognize the cost of the equity awards expected to vest over the period the awards vest. See Note 15, Share-Based Compensation, for more information.
Research and Development	Research and Development Research and development costs are expensed as incurred. The amount charged to expense was $16.0 million, $14.4 million, and $12.8 million for the years ended December 31, 2019, 2018, and 2017, respectively.
Cash and Cash Equivalents	Cash and Cash Equivalents
Marketable Debt Securities	Marketable Debt Securities Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities
Trade Accounts Receivable, Allowance for Doubtful Accounts, and Customer Deductions	Trade Accounts Receivable, Allowance for Doubtful Accounts, and Customer Deductions Trade accounts receivable are stated at the amount we expect to collect. The collectability of our accounts receivable is based upon a combination of factors. In circumstances where a specific customer is unable to meet its financial obligations to PCA (e.g., bankruptcy filings, substantial downgrading of credit sources), a specific reserve for bad debts is recorded against amounts due to the Company to reduce the net recorded receivable to the amount the Company reasonably believes will be collected. For all other customers, reserves for bad debts are recognized based on historical collection experience. If collection experience deteriorates (i.e., higher than expected defaults or an unexpected material adverse change in a major customer’s ability to meet its financial obligations to the Company), the estimate of the recoverability of amounts due could be reduced by a material amount. We periodically review our allowance for doubtful accounts and adjustments to the valuation allowance are recorded as income or expense. Trade accounts receivable balances that remain outstanding after we have used reasonable collection efforts are written off through a charge to the valuation allowance and a credit to accounts receivable. At December 31, 2019 and 2018, the allowance for doubtful accounts was $4.2 million and $4.6 million, respectively. The customer deductions reserve represents the estimated amount required for customer returns, allowances, and earned discounts. Based on the Company’s experience, customer returns, allowances, and earned discounts have averaged approximately 1% of gross selling price. Accordingly, PCA reserves 1% of its open customer accounts receivable balance for these items. The reserves for customer deductions of $8.4 million
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The Company records its derivatives, if any, in accordance with ASC 815, Derivatives and Hedging
Fair Value Measurements	Fair Value Measurements PCA measures the fair value of its financial instruments and marketable debt securities in accordance with ASC 820, Fair Value Measurements and Disclosures Level 1 — Valuations based on quoted prices for identical assets and liabilities in active markets. Level 2 — Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data. Level 3 — Valuations based on unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Assets that are measured at fair value using the net asset value (NAV) per share as a practical expedient are not categorized within the fair value hierarchy. Financial instruments and marketable debt securities measured at fair value on a recurring basis include the fair values of our marketable debt securities and our pension and postretirement benefit assets and liabilities. See Note 12, Cash, Cash Equivalents, and Marketable Debt Securities, and Note 13, Employee Benefit Plans and Other Postretirement Benefits, for more information. Other assets and liabilities measured and recognized at fair value on a nonrecurring basis include assets acquired and liabilities assumed in acquisitions and our asset retirement obligations. Given the nature of these assets and liabilities, evaluating their fair value from the perspective of a market participant is inherently complex. Assumptions and estimates about future values can be affected by a variety of internal and external factors. Changes in these factors may require us to revise our estimates and could require us to retroactively adjust provisional amounts that we recorded for the fair values of assets acquired and liabilities assumed in connection with business combinations. These adjustments could have a material effect on our financial condition and results of operations. See Note 5, Acquisitions, and Note 14, Asset Retirement Obligations, for more information.
Inventory Valuation	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.
Property, Plant, and Equipment	Property, Plant, and Equipment Property, plant, and equipment are recorded at cost. Cost includes expenditures for major improvements and replacements and the amount of interest cost associated with significant capital additions. Repairs and maintenance costs are expensed as incurred .
Depreciation and Useful Life	Depreciation is computed on the straight-line basis over the estimated useful lives of the related assets. Assets under finance leases are depreciated on the straight-line method over the term of the lease or the useful life, if shorter. The following lives are used for the various categories of assets: Buildings and land improvements 5 to 40 years Machinery and equipment 3 to 25 years Trucks and automobiles 3 to 10 years Furniture and fixtures 3 to 20 years Computers and hardware 3 to 10 years Leasehold improvements Period of the lease life, if shorter
Leases	Leases We determine if an arrangement is, or contains, a lease at the inception date based on the presence of identified assets and our right to obtain substantially all of the economic benefit from or to direct the use of such assets. When we determine a lease exists, we record a right-of-use asset and corresponding lease liability on our consolidated balance sheets. Right-of-use assets represent our right to use an underlying asset for the lease term. Lease liabilities represent our obligation to make lease payments arising from the lease. Right-of-use assets are recognized at commencement date at the value of the lease liability and are adjusted for any prepayments, lease incentives received, and initial direct costs incurred. Lease liabilities are recognized at lease commencement date based on the present value of remaining lease payments over the lease term. As the discount rate implicit in the lease is not readily determinable in most of our leases, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. Our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease balances are included in Operating lease right-of-use assets with the related liabilities included in Current Operating lease obligations and Long-term Operating lease obligations. Assets under finance leases are included in Property, plant and equipment, net, with the related liabilities included in Current Finance lease obligations and Long-term Finance lease obligations . We do not record lease contracts with a term of 12 months or less on our consolidated balance sheets. We recognize fixed lease expense for operating leases on a straight-line basis over the lease term. For finance leases, we recognize amortization expense on the right-of-use asset and interest expense on the lease liability over the lease term. We have lease agreements with non-lease components that relate to lease components (e.g., common area maintenance such as cleaning or landscaping, insurance, etc.). We account for each lease and any non-lease components associated with that lease as a single lease
Long-Lived Asset Impairment	Long-Lived Asset Impairment Long-lived assets other than goodwill and other intangibles are reviewed for impairment in accordance with provisions of ASC 360, Property, Plant and Equipment
Goodwill and Intangible Assets	Goodwill and Intangible Assets The Company has capitalized certain intangible assets, primarily goodwill, customer relationships, and trademarks and trade names, based on their estimated fair value at the date of acquisition. Amortization is provided for customer relationships on a straight-line basis over periods ranging from ten to 40 years, and trademarks and trade names over periods ranging from five to 20 years. Goodwill, which amounted to $918.7 million and $917.3 million for the years ended December 31, 2019 and 2018, respectively, is not amortized but is subject to an annual impairment test in accordance with ASC 350, Intangibles – Goodwill and Other.
Pension and Postretirement Benefits	Pension and Postretirement Benefits Several estimates and assumptions are required to record pension costs and liabilities, including discount rate, return on assets, and longevity and service lives of employees. We review and update these assumptions annually unless a plan curtailment or other event occurs, requiring that we update the estimates on an interim basis. While we believe the assumptions used to measure our pension and postretirement benefit obligations are reasonable, differences in actual experience or changes in assumptions may materially affect our pension and postretirement benefit obligations and future expense. See Note 13, Employee Benefit Plans and Other Postretirement Benefits, for additional information. For postretirement health care plan accounting, the Company reviews external data and its own historical trends for health care costs to determine the health care cost trend rate assumption.
Environmental Matters	Environmental Matters Environmental expenditures that extend the life of the related property or mitigate or prevent future environmental contamination are capitalized. Liabilities are recorded for environmental contingencies when such costs are probable and reasonably estimable. These liabilities are adjusted as further information develops or circumstances change. Environmental expenditures related to existing conditions resulting from past or current operations from which no current or future benefit is discernible are expensed as incurred.
Asset Retirement Obligations	Asset Retirement Obligations The Company accounts for its retirement obligations related predominantly to landfill closure, wastewater treatment pond dredging, closed-site monitoring costs, and certain leasehold improvements under ASC 410, Asset Retirement and Environmental Obligations
Deferred Debt Issuance Costs	Deferred Debt Issuance Costs PCA has capitalized certain costs related to obtaining its financing. These costs are amortized to interest expense using the effective interest rate method over the terms of the related financing, which range from 10 to 30 years. At December 31, 2019 and 2018 deferred debt issuance costs were $16.3 million and $12.6 million, respectively, and were recorded in “Long-Term Debt” on our Consolidated Balance Sheets.
Cutting Rights and Fiber Farms	Cutting Rights and Fiber Farms We lease the cutting rights to approximately 73,000 acres of timberland. Additionally, we previously leased 3,000 acres of land where we operated fiber farms as a source of future fiber supply; however, we exited the leases in conjunction with the conversion of the No. 3 machine at the Wallula mill to produce virgin kraft linerboard. Management performed a recoverability test on the associated fiber farms in 2018 and 2017 and deemed the asset group to not be fully recoverable. As a result of the recoverability calculation on the fiber farm asset group, the Company recorded an impairment loss of $3.1 million and $13.5 million in 2018 and 2017, respectively. For our cutting rights, we capitalize the annual lease payments and reforestation costs associated with these leases. Costs are recorded as depletion when the timber or fiber is harvested and used in operations or sold to customers. Capitalized long-term lease costs for our cutting rights, primarily recorded in “Other long-term assets” on our Consolidated Balance Sheets, were $21.6 million and $22.4 million as of December 31, 2019 and 2018, respectively. The amount of depletion expense was $2.7 million, $7.6 million, and $5.2 million for the years ended December 31, 2019, 2018, and 2017, respectively.
Deferred Software Costs	Deferred Software Costs PCA capitalizes costs related to the purchase and development of software, which is used in its business operations. The costs attributable to these software systems are amortized over their estimated useful lives based on various factors such as the effects of obsolescence, technology, and other economic factors. Net capitalized software costs recorded in “Other long-term assets” on our Consolidated Balance Sheets were $1.4 million and $1.6 million for the years ended December 31, 2019 and 2018, respectively. Software amortization expense was $0.9 million, $2.1 million, and $2.3 million for the years ended December 31, 2019, 2018, and 2017, respectively. During 2019, the Company early adopted ASU 2018-15, Intangibles – Goodwill and Other – Internal Use Software Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract
Income Taxes	Income Taxes PCA utilizes the liability method of accounting for income taxes whereby it recognizes deferred tax assets and liabilities for the future tax consequences of temporary differences between the tax basis of assets and liabilities and the reported amounts in the financial statements. Deferred tax assets will be reduced by a valuation allowance if, based upon management’s estimates, it is more likely than not that a portion of the deferred tax assets will not be realized in a future period. The estimates utilized in the recognition of deferred tax assets are subject to revision in future periods based on new facts or circumstances. PCA’s practice is to recognize interest and penalties related to unrecognized tax benefits in income tax expense.
Trade Agreements	Trade Agreements PCA regularly trades containerboard with other manufacturers primarily to reduce shipping costs. These agreements are entered into with other producers on an annual basis, pursuant to which both parties agree to ship an identical number of tons of containerboard to each other within the agreement period. These agreements lower transportation costs by allowing each party’s containerboard mills to ship containerboard to the other party’s closer corrugated products plant. PCA tracks each shipment to ensure that the other party’s shipments to PCA match PCA’s shipments to the other party during the agreement period. Such transfers are possible because containerboard is a commodity product with no distinguishing product characteristics. These transactions are accounted for at carrying value, and revenue is not recorded as the transactions do not represent the culmination of an earnings process. The transactions are recorded into inventory accounts, and no sale or income is recorded until such inventory is converted to a finished product and sold to an end-use customer. Business Combinations The Company accounts for acquisitions under ASC 805, Business Combinations Clarifying the Definition of a Business
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards Effective January 1, 2019, the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2016-02 (Topic 842): Leases , which requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous guidance. The original guidance required application on a modified retrospective basis with the earliest period presented. In July 2018, the FASB issued ASU 2018-11, Targeted Improvements to ASC 842 , which included an option to not restate comparative periods in transition and elect to use the effective date of ASC 842, Leases , as the date of initial application of transition, which we elected. As a result of the adoption of ASC 842 on January 1, 2019, we recorded operating lease liabilities of $228 million, with corresponding right-of-use assets of the same amount. In addition, we elected the package of practical expedients permitted under the transition guidance within the new standard, which allowed us to carry forward the historical lease classification and not to reassess whether existing or expired contracts contain a lease. We also elected the short-term lease recognition exemption, which permits us to exclude short-term leases (i.e. leases with terms of 12 months or less) from the recognition requirements of this standard, and we elected to account for lease and non-lease components as a single lease component for all classes of underlying assets except for embedded leases. The adoption of ASC 842 had an immaterial impact on our consolidated net earnings, liquidity and debt covenants under our current agreements for the year ended December 31, 2019. See Note 3, Leases, for more information. Effective January 1, 2019, we adopted ASU 2018-02 (Topic 220 ): Income Statement—Reporting Comprehensive Income – Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income Tax Act. As a result, the adoption did not have an impact on the Company's financial position, results of operations, or cash flow . Effective October 1, 2019, we early adopted ASU 2018-15, Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which includes amendments to align the accounting for costs incurred to implement a cloud computing arrangement that is a service contract with the guidance on capitalizing costs associated with developing or obtaining internal-use software. The accounting for the service component of a hosting arrangement that is a service contract is not affected by the amendments in this update. This guidance will be applied prospectively. The adoption of this guidance did not have a material impact on the Company’s financial condition, results of operations, or cash flows.
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 of this guidance, but does not expect the guidance will have a significant impact 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 this guidance, but does not expect the guidance will have a significant impact on its related disclosures. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326) : Measurement of Credit Losses on Financial Instruments. ASU 2016-13 introduces the Current Expected Credit Losses (“CECL”) framework for evaluating credit losses on financial instruments measured at amortized cost. This new framework requires entities to incorporate forward-looking information into their estimate of current expected credit loss as of each reporting date. Although available-for-sale (“AFS”) debt securities are not within the scope of the new CECL framework, the ASU includes an amended impairment model for evaluating losses related to AFS debt securities. The guidance in this update also includes enhanced requirements for disclosures related to credit loss estimates. The ASU is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. The amendments in ASU 2016-13 would need to be applied using the modified retrospective method. The Company is currently evaluating the impact of the new guidance but does not expect this ASU to have a material impact on the Company’s financial position, results of operation, or cash flow. 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.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Components of Inventories	The components of inventories were as follows (dollars in millions): December 31, 2019 2018 Raw materials $ 271.5 $ 307.8 Work in process 11.0 13.9 Finished goods 207.7 199.0 Supplies and materials 303.9 274.9 Inventories $ 794.1 $ 795.6
Property, Plant and Equipment (at cost)	Property, plant, and equipment consisted of the following (dollars in millions): December 31, 2019 2018 Land and land improvements $ 177.5 $ 161.9 Buildings 837.4 795.5 Machinery and equipment 5,727.4 5,481.6 Construction in progress 174.0 176.7 Other 81.5 75.4 Property, plant and equipment, at cost 6,997.8 6,691.1 Less accumulated depreciation (3,846.1 ) (3,582.5 ) Property, plant and equipment, net $ 3,151.7 $ 3,108.6
Property, Plant and Equipment Estimated Useful Lives	Depreciation is computed on the straight-line basis over the estimated useful lives of the related assets. Assets under finance leases are depreciated on the straight-line method over the term of the lease or the useful life, if shorter. The following lives are used for the various categories of assets: Buildings and land improvements 5 to 40 years Machinery and equipment 3 to 25 years Trucks and automobiles 3 to 10 years Furniture and fixtures 3 to 20 years Computers and hardware 3 to 10 years Leasehold improvements Period of the lease life, if shorter

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of Supplemental Balance Sheet Information Related to Operating Leases	Supplemental balance sheet information related to our operating leases at December 31, 2019 was as follows (dollars in millions): Operating lease right-of-use assets $ 234.3 Current portion of operating lease obligations $ 62.6 Long-term portion of operating lease obligations 177.6 Total operating lease obligations $ 240.2
Schedule of Supplemental Balance Sheet Information Related to Finance Leases	Supplemental balance sheet information related to our finance leases was as follows (dollars in millions): Year Ended December 31, 2019 2018 Buildings $ 0.3 $ 0.3 Machinery and equipment 28.5 28.5 Total 28.8 28.8 Less accumulated amortization (18.1 ) (16.7 ) Total $ 10.7 $ 12.1 Current portion of finance lease obligations $ 1.5 $ 1.4 Long-term portion of finance lease obligations 16.0 17.6 Total finance lease obligations $ 17.5 $ 19.0
Schedule of Weighted Average Remaining Lease Term and Weighted Average Discount Rates for Leases	For both operating and finance leases, the weighted average remaining lease term in years and weighted average discount rates at December 31, 2019 were as follows: Weighted-average remaining lease term (years): Operating leases 5.6 Finance leases 8.8 Weighted-average discount rate: Operating leases 4.23% Finance leases 6.66%
Components of Lease Expense	The components of lease expense for the full year ended December 31, 2019 were as follows (dollars in millions): Finance lease cost: Amortization of finance lease assets $ 1.5 Interest on lease liabilities 1.2 Total finance lease cost 2.7 Operating lease cost 70.2 Short-term lease cost 19.2 Variable lease cost 13.7 Total lease cost $ 105.8
Schedule of Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases for the full year ended December 31, 2019 was as follows (dollars in millions): Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ (60.0 ) Operating cash flows for finance leases (1.5 ) Financing cash flows for finance leases (1.2 ) Right-of-use assets obtained in exchange for new lease obligations: Operating leases $ (27.7 ) Finance leases — Supplemental non-cash information on changes in lease liabilities $ 44.5 Supplemental non-cash information on changes in right-of-use assets $ 21.4
Schedule of Future Minimum Payments Under Operating and Finance Lease Liabilities	The future minimum payments under operating and finance lease liabilities at December 31, 2019 were as follows (dollars in millions): Operating Leases Finance Leases 2020 $ 71.2 $ 2.7 2021 60.6 2.7 2022 42.8 2.7 2023 28.7 2.7 2024 20.2 2.7 Thereafter 48.0 9.7 Total lease payments 271.5 23.2 Less imputed interest (a) (31.3 ) (5.7 ) Present value of lease liabilities $ 240.2 $ 17.5 (a) Calculated using the incremental borrowing rate for each lease applied to the future payments.
Schedule of Future Minimum Payments Under Operating and Finance Lease Liabilities Under ASU 840	The future minimum payments under operating and finance lease liabilities at December 31, 2018 under ASC 840 were as follows (dollars in millions): Operating Leases Finance Leases 2019 $ 70.1 $ 2.7 2020 58.7 2.7 2021 47.4 2.7 2022 29.9 2.7 2023 17.8 2.7 Thereafter 46.4 12.4 Total lease payments $ 270.3 25.9 Less imputed interest (b) (6.9 ) Present value of lease liabilities $ 19.0 (b) Calculated using the incremental borrowing rate for each lease applied to the future payments.

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2019
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): Year Ended December 31, 2019 2018 2017 (a) Packaging $ 5,932.2 $ 5,938.5 $ 5,312.3 Paper 964.3 1,002.0 1,051.8 Corporate and Other 67.8 74.1 80.8 Total revenue $ 6,964.3 $ 7,014.6 $ 6,444.9 _______________ (a) 2017 has not been adjusted under the modified retrospective method for Topic 606.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
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). Year Ended December 31, 2019 2018 2017 Numerator: Net income $ 696.4 $ 738.0 $ 668.6 Less: distributed and undistributed earnings allocated to participating securities (5.2 ) (5.7 ) (5.6 ) Net income attributable to common stockholders $ 691.2 $ 732.3 $ 663.0 Denominator: Weighted average common shares outstanding 93.8 93.7 93.5 Effect of dilutive securities 0.3 0.2 0.2 Diluted common shares outstanding 94.1 93.9 93.7 Basic income per common share $ 7.36 $ 7.82 $ 7.09 Diluted income per common share $ 7.34 $ 7.80 $ 7.07

Other (Expense) Income, Net (Ta

Other (Expense) Income, Net (Tables)	12 Months Ended
	Dec. 31, 2019
Other Income And Expenses [Abstract]
Components of Other (Expense) Income, Net	The components of other (expense) income, net, were as follows (dollars in millions): Year Ended December 31, 2019 2018 2017 Asset disposals and write-offs (a) $ (25.0 ) $ (17.3 ) $ (10.5 ) Wallula mill restructuring (b) (0.7 ) (14.9 ) (23.1 ) Facilities closure and other costs (c) (0.3 ) (1.6 ) 5.9 Insurance deductible for property damage (d) — (0.5 ) — Acquisition and integration related costs (e) — (0.2 ) (0.8 ) DeRidder mill incident (f) — — 9.7 Hexacomb working capital adjustment (g) — — 2.3 Expiration of timberland repurchase option (h) — — 2.0 Other (6.7 ) (6.7 ) (3.9 ) Total $ (32.7 ) $ (41.2 ) $ (18.4 ) (a) For 2019, includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill. (b ) Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to produce virgin kraft linerboard. (c ) For 2019, includes charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility. For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes income primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, a paper administration facility, a corporate administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. ( d ) Includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities. (e ) Includes charges for acquisition and integration costs related to recent acquisitions. (f ) Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill. ( g ) Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico. ( h ) Includes a gain related to the expiration of a repurchase option corresponding to timberland previously sold.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Components of Consolidated Income Tax Provision	The following is an analysis of the components of the consolidated income tax provision (dollars in millions): Year Ended December 31, 2019 2018 2017 Current income tax provision (benefit) - U.S. federal $ 123.2 $ 150.7 $ 209.3 State and local 37.0 42.9 34.9 Foreign 0.1 0.2 0.3 Total current provision for taxes 160.3 193.8 244.5 Deferred - U.S. federal 55.3 34.7 (90.2 ) State and local 5.0 4.0 5.7 Foreign — — — Total deferred provision (benefit) for taxes 60.3 38.7 (84.5 ) Total provision for taxes $ 220.6 $ 232.5 $ 160.0
Summary of Effective Tax Rate	The effective tax rate varies from the U.S. federal statutory tax rate principally due to the following (dollars in millions): 2019 2018 2017 Provision computed at U.S. federal statutory rate (a) $ 192.6 $ 203.8 $ 290.0 Federal tax reform — (2.0 ) (127.2 ) State and local taxes, net of federal benefit 35.7 36.9 24.0 Domestic manufacturers deduction (b) — — (21.1 ) Other (7.7 ) (6.2 ) (5.7 ) Total $ 220.6 $ 232.5 $ 160.0 (a) U.S. federal statutory rate of 21% (b) The domestic manufacturers deduction was eliminated after 2017 as a result of the Tax Cuts and Jobs Act.
Details of Scheduled Expiration Dates of Tax Effected Net Operating Loss (NOL) and Other Tax Carryforwards	The following details the scheduled expiration dates of our tax effected net operating loss (NOL) and other tax carryforwards at December 31, 2019 (dollars in millions): 2020 Through 2029 2030 Through 2039 Indefinite Total U.S. federal NOLs $ 29.0 $ — $ — $ 29.0 State taxing jurisdiction NOLs 1.6 0.2 — 1.8 U.S. federal tax credit carryforwards 0.1 — — 0.1 U.S. federal and non-U.S. capital loss carryforwards 3.0 — 0.1 3.1 Total $ 33.7 $ 0.2 $ 0.1 $ 34.0
Deferred Income Tax Assets and Liabilities	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts for income tax purposes. Deferred income tax assets and liabilities at December 31 are summarized as follows (dollars in millions): December 31, 2019 2018 Deferred tax assets: Pension and postretirement benefits $ 90.7 $ 87.4 Lease obligations 59.2 — Employee benefits and compensation 35.5 37.7 Net operating loss carryforwards 30.8 34.4 Inventories 14.1 12.6 Restricted stock and performance units 11.2 10.2 Accrued liabilities 6.1 17.1 Capital loss and general business credit carryforwards 3.2 3.3 Derivatives 0.1 4.7 Gross deferred tax assets 250.9 207.4 Valuation allowance (c) (3.0 ) (3.1 ) Net deferred tax assets $ 247.9 $ 204.3 Deferred tax liabilities: Property, plant and equipment $ (459.1 ) $ (422.3 ) Goodwill and intangible assets (70.8 ) (67.2 ) Right-of-use assets (58.1 ) — Total deferred tax liabilities $ (588.0 ) $ (489.5 ) Net deferred tax liabilities (d) $ (340.1 ) $ (285.2 ) (c ) Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion of the deferred tax assets will not be realized. Both the 2019 and 2018 valuation allowance relates to capital losses. We do not expect to generate capital gains before the capital losses expire. If or when recognized, the tax benefits relating to the reversal of any or all of the valuation allowance would be recognized as a benefit to income tax expense. (d ) As of December 31, 2019, we did not recognize U.S. deferred income taxes on our cumulative total of undistributed foreign earnings for our foreign subsidiaries. We indefinitely reinvest our earnings in operations outside the United States. It is not practicable to determine the amount of unrecognized deferred tax liability on these undistributed earnings because the actual tax liability, if any, is dependent on circumstances existing when the repatriation occurs.
Summary of Changes Related to PCA’s Gross Unrecognized Tax Benefits Excluding Interest and Penalties	The following table summarizes the changes related to PCA’s gross unrecognized tax benefits excluding interest and penalties (dollars in millions): 2019 2018 2017 Balance as of January 1 $ (4.6 ) $ (4.8 ) $ (5.2 ) Increases related to prior years’ tax positions (0.1 ) (0.1 ) — Increases related to current year tax positions (0.4 ) (0.3 ) (0.4 ) Decreases related to prior years' tax positions — — — Settlements with taxing authorities — — — Expiration of the statute of limitations 0.3 0.6 0.8 Balance at December 31 $ (4.8 ) $ (4.6 ) $ (4.8 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying amount of our goodwill were as follows (dollars in millions): Total Packaging Paper Goodwill Balance at January 1, 2018 $ 828.0 $ 55.2 $ 883.2 Acquisitions (a)(b) 34.1 — 34.1 Balance at December 31, 2018 862.1 55.2 917.3 Acquisitions (c) 1.4 — 1.4 Balance at December 31, 2019 $ 863.5 $ 55.2 $ 918.7 (a) During 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container. (b ) In connection with the October 2018 acquisition of Englander, the Company recorded $28.6 million of goodwill in the Packaging segment in 2018. (c) During 2019, the Company recorded a $1.4 million adjustment to increase the goodwill balance for the Company’s October 2018 acquisition of Englander.
Components of Intangible Assets	The weighted average useful life, gross carrying amount, and accumulated amortization of our intangible assets were as follows (dollars in millions): As of December 31, 2019 As of December 31, 2018 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 (d)(e) 10.0 $ 503.8 $ 180.2 10.9 $ 504.6 $ 144.5 Trademarks and trade names (e) 9.5 34.8 20.6 10.1 34.8 18.3 Other (e) 2.1 4.3 3.3 3.0 4.4 2.7 Total intangible assets (excluding goodwill) 9.9 $ 542.9 $ 204.1 10.8 $ 543.7 $ 165.5 (d) During 2019, a corrugated products facility sold part of its operations which included existing inventory, certain production equipment, and customer relationships corresponding to the operations sold. As a result, the gross carrying amount for the customer relationships intangible asset was decreased by $0.7 million. (e ) In connection with the October 2018 acquisition of Englander, the Company recorded intangible assets of $13.2 million for customer relationships, $0.8 million for trade names, and $0.1 million for other intangibles.

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Accrued Liabilities Current And Noncurrent [Abstract]
Components of Accrued Liabilities	The components of accrued liabilities were as follows (dollars in millions): December 31, 2019 2018 Compensation and benefits $ 124.5 $ 136.7 Customer volume discounts and rebates 27.9 25.2 Medical insurance and workers’ compensation 26.3 27.5 Franchise, property, sales and use taxes 15.3 13.4 Environmental liabilities and asset retirement obligations 5.6 5.0 Severance, retention, and relocation 3.5 2.2 Other 14.4 12.4 Total $ 217.5 $ 222.4

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Summary of Debt	At December 31, 2019 and 2018, our long-term debt and interest rates on that debt were as follows (dollars in millions): December 31, 2019 December 31, 2018 Amount Interest Rate Amount Interest rate Revolving Credit Facility, due August 2021 $ — — % $ — — % 2.45% Senior Notes, net of discount of $0.4 million as of December 31, 2018, due December 2020 — — % 499.6 2.45 % 3.90% Senior Notes, net of discount of $0.1 million as of December 31, 2018, due June 2022 — — % 399.9 3.90 % 4.50% Senior Notes, net of discount of $0.8 million and $1.0 million as of December 31, 2019 and 2018, respectively, due November 2023 699.2 4.50 % 699.0 4.50 % 3.65% Senior Notes, net of discount of $0.6 million and $0.7 million as of December 31, 2019 and 2018, respectively, due September 2024 399.4 3.65 % 399.3 3.65 % 3.40% Senior Notes, net of discount of $1.3 million and $1.5 million as of December 31, 2019 and 2018, respectively, due December 2027 498.7 3.40 % 498.5 3.40 % 3.00% Senior Notes, net of discount of $0.7 million as of December 31, 2019, due December 2029 499.3 3.00 % — — % 4.05% Senior Notes, net of discount of $3.5 million as of December 31, 2019, due December 2049 396.5 4.05 % — — % Total 2,493.1 3.77 % 2,496.3 3.64 % Less current portion — — % — — % Less unamortized debt issuance costs 16.3 12.6 Total long-term debt $ 2,476.8 3.77 % $ 2,483.7 3.64 %

Cash, Cash Equivalents, and M_2

Cash, Cash Equivalents, and Marketable Debt Securities (Tables)	12 Months Ended
	Dec. 31, 2019
Cash Cash Equivalents And Short Term Investments [Abstract]
Schedule of Cash and Available-For-Sale Debt Securities by Major Asset Category	The following table shows the Company’s cash and available-for-sale (AFS) debt securities by major asset category at December 31, 2019 (in millions): Adjusted Cost Basis Fair Value (c) Cash and Cash Equivalents Short-Term Marketable Debt Securities Long-Term Marketable Debt Securities Cash and cash equivalents $ 675.6 $ 675.6 $ 675.6 $ — $ — Level 1 (a) Money market funds 0.1 0.1 0.1 — — U.S. Treasury securities 27.1 27.1 3.1 11.5 12.5 Subtotal 27.2 27.2 3.2 11.5 12.5 Level 2 (b) Certificates of deposit 3.9 3.9 — 3.9 — Commercial paper 5.6 5.6 0.7 4.9 — U.S. government agency securities 7.0 7.0 — 3.0 4.0 Corporate debt securities 106.2 106.2 — 64.6 41.6 Subtotal 122.7 122.7 0.7 76.4 45.6 Total $ 825.5 $ 825.5 $ 679.5 $ 87.9 $ 58.1
Schedule of Market Value of Marketable Debt Securities with Continuous Unrealized Losses	The market value of marketable debt securities with continuous unrealized losses as of December 31, 2019 was as follows (in millions): 2019 Continuous Unrealized Losses Less than 12 Months 12 Months or Greater Total Fair value of marketable debt securities $ 78.1 $ — $ 78.1 Unrealized losses $ — $ — $ —

Employee Benefit Plans and Ot_2

Employee Benefit Plans and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Schedule of Obligations and Funded Status of Defined Benefit Pension and Postretirement Benefit Plans	The following table, which includes only company-sponsored defined benefit and other postretirement benefit plans, reconciles the beginning and ending balances of the projected benefit obligation and the fair value of plan assets. We recognize the unfunded status of these plans on the Consolidated Balance Sheets, and we recognize changes in funded status in the year changes occur through the Consolidated Statements of Comprehensive Income (dollars in millions): Pension Plans Postretirement Plans Year Ended December 31 Year Ended December 31 2019 2018 2019 2018 Change in Benefit Obligation Benefit obligation at beginning of period $ 1,204.9 $ 1,300.2 $ 14.6 $ 16.5 Service cost 24.5 25.0 0.3 0.3 Interest cost 47.0 42.4 0.5 0.5 Plan amendments 2.3 3.0 (0.3 ) (0.4 ) Actuarial (gain) loss (a) 188.6 (121.1 ) 0.2 (1.2 ) Participant contributions — — 1.1 1.1 Benefits paid (47.2 ) (44.6 ) (1.9 ) (2.2 ) Benefit obligation at plan year end $ 1,420.1 $ 1,204.9 $ 14.5 $ 14.6 Accumulated benefit obligation portion of above $ 1,374.4 $ 1,163.3 Change in Fair Value of Plan Assets Plan assets at fair value at beginning of period $ 873.2 $ 954.8 $ — $ — Actual return on plan assets 188.9 (59.9 ) — — Company contributions 58.9 22.9 0.8 1.1 Participant contributions — — 1.1 1.1 Benefits paid (47.2 ) (44.6 ) (1.9 ) (2.2 ) Fair value of plan assets at plan year end $ 1,073.8 $ 873.2 $ — $ — Underfunded status $ (346.3 ) $ (331.7 ) $ (14.5 ) $ (14.6 ) Amounts Recognized on Consolidated Balance Sheets Current liabilities (1.4 ) (1.4 ) (0.7 ) (0.8 ) Noncurrent liabilities (344.9 ) (330.3 ) (13.8 ) (13.8 ) Accrued obligation recognized at December 31 $ (346.3 ) $ (331.7 ) $ (14.5 ) $ (14.6 ) Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax) Prior service cost (credit) $ 24.7 $ 28.7 $ (5.3 ) $ (5.4 ) Actuarial loss (gain) 239.2 194.6 (4.4 ) (5.0 ) Total $ 263.9 $ 223.3 $ (9.7 ) $ (10.4 ) (a) The actuarial loss in 2019 was due primarily to a decrease in the weighted average discount rate used to estimate pension benefit obligations. The actuarial gain in 2018 was due primarily to an increase in the weighted average discount rate used to estimate our pension benefit obligations.
Components of Net Periodic Benefit Costs and Other Comprehensive (Income) Loss (Pretax)	The components of net periodic benefit cost and other comprehensive (income) loss (pretax) were as follows (dollars in millions): Pension Plans Postretirement Plans Year Ended December 31, Year Ended December 31, 2019 2018 2017 2019 2018 2017 Service cost $ 24.5 $ 25.0 $ 23.7 $ 0.3 $ 0.3 $ 0.3 Interest cost 47.0 42.4 41.6 0.5 0.5 0.6 Expected return on plan assets (52.1 ) (56.7 ) (53.9 ) — — — Net amortization of unrecognized amounts Prior service cost (credit) 6.3 6.9 5.8 (0.3 ) (0.3 ) (0.2 ) Actuarial loss (gain) 7.0 9.4 7.6 (0.4 ) (0.2 ) (0.1 ) Net periodic benefit cost $ 32.7 $ 27.0 $ 24.8 $ 0.1 $ 0.3 $ 0.6 Changes in plan assets and benefit obligations recognized in other comprehensive (income) loss Actuarial net loss (gain) $ 51.8 $ (4.6 ) $ 32.2 $ 0.2 $ (1.2 ) $ (2.2 ) Prior service cost (credit) 2.3 3.0 17.4 (0.3 ) (0.3 ) (0.6 ) Amortization of prior service cost (credit) (6.3 ) (6.9 ) (5.8 ) 0.3 0.3 0.2 Amortization of actuarial loss (gain) (7.0 ) (9.4 ) (7.6 ) 0.4 0.2 0.1 Total recognized in other comprehensive loss (income) (b) $ 40.8 $ (17.9 ) $ 36.2 $ 0.6 $ (1.0 ) $ (2.5 ) Total recognized in net periodic benefit cost and other comprehensive loss (income) (pre-tax) $ 73.5 $ 9.2 $ 61.0 $ 0.7 $ (0.7 ) $ (1.9 ) (b ) Accumulated losses in excess of 10% of the greater of the projected benefit obligation or the market-related value of assets will be recognized on a straight-line basis over the average remaining service period of active employees in PCA plans (which is between seven and ten years) and over the average remaining lifetime of inactive participants of Boise plans (which is between 24 and 27 years), to the extent that losses are not offset by gains in subsequent years. The estimated net loss and prior service cost that will be amortized from “Accumulated other comprehensive loss” into net periodic benefit in 2020 is $14.3 million.
Weighted-Average Assumptions Used To Determine Benefit Obligations and Net Periodic Benefit Cost	The following table presents the assumptions used in the measurement of our benefits obligations: Pension Plans Postretirement Plans December 31, December 31, 2019 2018 2017 2019 2018 2017 Weighted-Average Assumptions Used to Determine Benefit Obligations at December 31 Discount rate 3.25% 4.31% 3.66% 3.18% 4.21% 3.55% Rate of compensation increase 4.00% 4.00% 4.00% N/A N/A N/A Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost for the Years Ended December 31 Discount rate 4.31% 3.66% 4.24% 4.21% 3.57% 3.92% Expected return on plan assets 6.06% 6.06% 6.55% N/A N/A N/A Rate of compensation increase 4.00% 4.00% 4.00% N/A N/A N/A
Assumed Health Care Cost Trend Rates For Postretirement Benefits	Health Care Cost Trend Rate Assumptions. PCA assumed health care cost trend rates for its postretirement benefits plans were as follows: 2019 2018 2017 Health care cost trend rate assumed for next year 7.09% 7.24% 7.57% Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50% 4.44% 4.44% Year that the rate reaches the ultimate trend rate 2029 2028 2027
Schedule of Effects of One-Percentage Point Change In Assumed Health Care Cost Trend Rates on Postretirement Benefits	A one-percentage point change in assumed health care cost trend rates would have the following effects on the 2019 postretirement benefit obligation and the 2018 net postretirement benefit cost (dollars in millions): 1-Percentage Point Increase 1-Percentage Point Decrease Effect on postretirement benefit obligation $ 0.5 $ (0.5 ) Effect on net postretirement benefit cost 0.1 —
Schedule of Pension Plans' Assets Investment Policies and Strategies	Assets of our pension plans were invested in the following classes of securities at December 31, 2019 and 2018: Percentage of Fair Value at December 31, 2019 2018 Fixed income securities 50 % 53 % International equity securities 27 % 27 % Domestic equity securities 22 % 18 % Other 1 % 2 %
Schedule of Fair Value Measurements of Plan Assets by Major Asset Category	The following tables set forth, by level within the fair value hierarchy, discussed in Note 2, Summary of Significant Accounting Policies, the pension plan assets, by major asset category, at fair value at December 31, 2019 and 2018 (dollars in millions): Fair Value Measurements at December 31, 2019 Asset Category Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value (NAV) (a) Total Cash and short-term investments $ — $ 14.9 $ — $ — $ 14.9 Common/collective trust funds: International equities 163.0 20.8 — 102.3 286.1 Domestic equities — 240.5 — — 240.5 Corporate and government bonds: Fixed income 140.4 154.6 — — 295.0 Government bonds and agencies — 160.7 — — 160.7 Corporate bonds — 70.6 — — 70.6 Municipal bonds — 5.8 — — 5.8 Private equity securities (b) — — 2.6 — 2.6 Total securities at fair value $ 303.4 $ 667.9 $ 2.6 $ 102.3 $ 1,076.2 Accrued expenses and receivables (2.4 ) Total fair value of plan assets $ 1,073.8 Fair Value Measurements at December 31, 2018 Asset Category Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Net Asset Value (NAV) (a) Total Cash and short-term investments $ 0.4 $ 11.6 $ — $ — $ 12.0 Common/collective trust funds: Domestic equities — 154.5 — — 154.5 International equities 136.9 17.8 — 84.1 238.8 Corporate and government bonds: Government bonds 155.0 9.4 — 164.4 Corporate bonds — 64.4 — 64.4 Fixed income 95.7 138.8 — — 234.5 Private equity securities (b) — — 3.3 — 3.3 Total securities at fair value $ 388.0 $ 396.5 $ 3.3 $ 84.1 $ 871.9 Receivables and accrued expenses 1.3 Total fair value of plan assets $ 873.2 (a) In accordance with ASC 820, Fair Value Measurement ( b ) Investments in this category are invested in the Pantheon Global Secondary Fund IV, LP. The fund specializes in investments in the private equity secondary market and occasionally directly in private companies to maximize capital growth. Fund investments are carried at fair value as determined quarterly using the market approach to estimate the fair value of private investments. The market approach utilizes prices and other relevant information generated by market transactions, type of security, size of the position, degree of liquidity, restrictions on the disposition, latest round of financing data, current financial position, and operating results, among other factors. In circumstances where fair values are not provided with respect to any of the company's fund investments, the investment advisor will seek to determine the fair value of such investments based on information provided by the general partners or managers of such funds or from other sources. Audited financial statements are provided by fund management annually. Notwithstanding the above, the variety of valuation bases adopted and quality of management data of the ultimate underlying investee companies means that there are inherent difficulties in determining the value of the investments. Amounts realized on the sale of these investments may differ from the calculated values. Boise had originally committed to a $ 15.0 million investment, with $ 5.0 million of the commitment unfunded at December 31, 2019 .
Summary of Changes in Pension Plans' Level 3 Assets	The following table sets forth a summary of changes in the fair value of the pension plans' Level 3 assets for the year ended December 31, 2019 (dollars in millions): 2019 Balance, beginning of year $ 3.3 Acquisitions — Purchases — Sales (0.7 ) Unrealized gain — Balance, end of year $ 2.6
Schedule of Estimated Benefit Payments	The following are estimated benefit payments to be paid to current plan participants by year (dollars in millions). Qualified pension benefit payments are paid from plan assets, while nonqualified pension benefit payments are paid by the Company. Pension Plans Postretirement Plans 2020 $ 52.7 $ 0.7 2021 56.7 0.7 2022 60.4 0.7 2023 64.1 0.7 2024 - 2029 442.5 4.5

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation [Abstract]
Changes to Asset Retirement Obligation	The following table describes changes to the asset retirement obligation liability (dollars in millions): Year Ended December 31, 2019 2018 Asset retirement obligation at beginning of period $ 30.0 $ 35.1 Accretion expense 1.5 1.6 Payments (3.5 ) (7.9 ) Revisions in estimated cash flows (0.2 ) 1.2 Asset retirement obligation at end of period $ 27.8 $ 30.0

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share Based Compensation [Abstract]
Summary of Restricted Stock Activity	A summary of the Company’s restricted stock activity follows: 2019 2018 2017 Shares Weighted Average Grant- Date Fair Value Shares Weighted Average Grant- Date Fair Value Shares Weighted Average Grant- Date Fair Value Restricted stock at January 1 743,591 $ 86.90 739,732 $ 77.23 786,079 $ 63.44 Granted 199,499 95.48 173,144 114.63 173,199 107.57 Vested (a) (212,809 ) 68.59 (165,547 ) 72.84 (213,992 ) 51.37 Forfeitures (13,329 ) 98.86 (3,738 ) 78.66 (5,554 ) 69.03 Restricted stock at December 31 716,952 $ 94.50 743,591 $ 86.90 739,732 $ 77.23 (a) The total fair value of awards upon vesting for the years ended December 31, 2019, 2018, and 2017 was $19.9 million, .
Summary of Performance Units Activity	A summary of the Company’s performance unit activity follows: 2019 2018 2017 Units Weighted Average Grant- Date Fair Value Units Weighted Average Grant- Date Fair Value Units Weighted Average Grant- Date Fair Value Performance units at January 1 266,704 $ 90.01 226,558 $ 77.07 232,088 $ 62.68 Granted 115,608 96.98 83,515 115.35 53,070 108.19 Vested (a) (59,165 ) 67.84 (43,369 ) 71.19 (58,600 ) 56.08 Performance units at December 31 323,147 $ 96.56 266,704 $ 90.01 226,558 $ 77.07 (a) The total fair value of awards upon vesting for the years ended December 31, 2019, 2018, and 2017 was $5.5 million, $5.4 million, and $7.5 million, respectively. Upon vesting of the awards in 2019, 2018, and 2017, PCA issued 59,165 shares, 46,876 shares, and 67,391 shares, respectively. For 2019, 2018, and 2017, these amounts included 6,063 shares, 3,507 shares, and 8,791 shares, respectively, for dividends accrued during the vesting period.
Compensation Expense for Share-Based Awards	Compensation expense for share-based awards recognized in the Consolidated Statements of Income, net of forfeitures was as follows (dollars in millions): Year Ended December 31, 2019 2018 2017 Restricted stock $ 22.6 $ 18.6 $ 15.0 Performance units 7.8 4.9 5.6 Impact on income before income taxes 30.4 23.5 20.6 Income tax benefit (7.6 ) (5.9 ) (7.9 ) Impact on net income $ 22.8 $ 17.6 $ 12.7
Unrecognized Compensation Expense for Share-Based Awards	The unrecognized compensation expense for all share-based awards was as follows (dollars in millions): December 31, 2019 Unrecognized Compensation Expense Remaining Weighted Average Recognition Period (in years) Restricted stock $ 27.2 3.1 Performance units 17.2 2.4 Total unrecognized share-based compensation expense $ 44.4 2.8

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Impact of Derivative Instruments on Consolidated Statements of Income and Accumulated OCI	The impact of derivative instruments on the consolidated statements of income and accumulated OCI was as follows (dollars in millions): Net Loss Recognized in Accumulated OCI (Effective Portion) December 31, 2019 2018 Treasury locks, net of tax $ — $ (10.2 ) Loss Reclassified from Accumulated OCI into Income (Effective Portion) Year Ended December 31, 2019 2018 2017 Amortization of treasury locks (included in interest expense, net) $ (18.2 ) $ (5.3 ) $ (5.7 )

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Components of Changes in Accumulated Other Comprehensive Income (AOCI)	Changes in AOCI, net of taxes, by component 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 December 31, 2018 $ (0.4 ) $ (10.2 ) $ (0.3 ) $ (127.9 ) $ (138.8 ) Other comprehensive income before reclassifications — — — (40.5 ) (40.5 ) Amounts reclassified from AOCI — 10.2 0.1 9.5 19.8 Net current-period other comprehensive income — 10.2 0.1 (31.0 ) (20.7 ) Balance at December 31, 2019 $ (0.4 ) $ — $ (0.2 ) $ (158.9 ) $ (159.5 )
Reclassifications Out of Accumulated Other Comprehensive Income (AOCI)	The following table presents information about reclassifications out of AOCI (dollars in millions). Amounts in parentheses indicate expenses in the Consolidated Statements of Income. Amounts Reclassified from AOCI Year Ended December 31, Details about AOCI Components 2019 2018 Unrealized loss on treasury locks, net (a) $ (18.1 ) $ (5.3 ) 7.9 1.3 Tax benefit $ (10.2 ) $ (4.0 ) Net of tax Unfunded employee benefit obligations (b) Amortization of prior service costs $ (6.0 ) $ (6.6 ) Amortization of actuarial gains / (losses) (6.7 ) (9.2 ) (12.7 ) (15.8 ) Total before tax 3.2 4.0 Tax benefit $ (9.5 ) $ (11.8 ) Net of tax (a) This AOCI component is included in interest expense, net. The remaining balances of the treasury locks were written off as a result of the Company’s November 2019 debt refinancing. For a discussion of treasury lock derivative instrument activity, see Note 16, Derivative Instruments and Hedging Activities, for additional information. (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)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Sales to External Customers by Product Line	Segment sales to external customers by product line were as follows (dollars in millions): Year Ended December 31, 2019 2018 2017 Packaging $ 5,932.2 $ 5,938.5 $ 5,312.3 Paper 964.3 1,002.0 1,051.8 Corporate and Other 67.8 74.1 80.8 $ 6,964.3 $ 7,014.6 $ 6,444.9
Analysis of Operations by Reportable Segment	An analysis of operations by reportable segment is as follows (dollars in millions): Sales, net Operating Depreciation, Year Ended December 31, 2019 Trade Inter- segment Total Income (Loss) Amortization, and Depletion Capital Expenditures (l) Assets Packaging $ 5,905.1 $ 27.1 $ 5,932.2 $ 963.4 (b) $ 342.8 $ 367.4 $ 5,491.5 Paper 964.3 — 964.3 175.4 (c) 37.7 23.8 791.4 Corporate and Other 94.9 133.1 228.0 (85.1 ) 7.0 8.3 952.9 Intersegment eliminations — (160.2 ) (160.2 ) — — — — $ 6,964.3 $ — $ 6,964.3 1,053.7 $ 387.5 $ 399.5 $ 7,235.8 Non-operating pension expense (7.9 ) Interest expense, net (128.8 ) (d) Income before taxes $ 917.0 Sales, net Operating Depreciation, Year Ended December 31, 2018 Trade Inter- segment Total Income (Loss) Amortization, and Depletion Capital Expenditures (l) Assets Packaging $ 5,912.3 $ 26.2 $ 5,938.5 $ 1,045.4 (e) $ 342.0 $ 504.0 $ 5,347.0 Paper 1,002.0 — 1,002.0 97.7 (f) 62.0 12.6 760.1 Corporate and Other 100.3 129.4 229.7 (75.4 ) (g) 6.9 34.8 462.6 Intersegment eliminations — (155.6 ) (155.6 ) — — — — $ 7,014.6 $ — $ 7,014.6 1,067.7 $ 410.9 $ 551.4 $ 6,569.7 Non-operating pension expense (2.1 ) Interest expense, net (95.1 ) Income before taxes $ 970.5 Sales, net Operating Depreciation, Year Ended December 31, 2017 Trade Inter- segment Total Income (Loss) (a) Amortization, and Depletion Capital Expenditures (l) Assets Packaging $ 5,288.6 $ 23.7 $ 5,312.3 $ 950.3 (h) $ 317.5 $ 305.1 $ 4,933.6 Paper 1,051.8 — 1,051.8 54.0 (i) 67.6 22.6 945.2 Corporate and Other 104.5 124.7 229.2 (71.8 ) (j) 6.3 15.3 318.7 Intersegment eliminations — (148.4 ) (148.4 ) — — — — $ 6,444.9 $ — $ 6,444.9 932.5 $ 391.4 $ 343.0 $ 6,197.5 Non-operating pension expense (1.3 ) Interest expense, net (102.6 ) (k) Income before taxes $ 828.6 (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 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) Year Ended December 31, 2017 As Reported Non-Operating Pension Adjustment Year Ended December 31, 2017 Adjusted Packaging $ 943.7 $ 6.6 $ 950.3 Paper 61.5 (7.5 ) 54.0 Corporate (74.0 ) 2.2 (71.8 ) Income from operations 931.2 1.3 932.5 Non-operating pension expense — (1.3 ) (1.3 ) Interest expense, net (102.6 ) — (102.6 ) Income before taxes $ 828.6 $ — $ 828.6 (b) Includes the following: o $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill. o $0.8 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility (c) Includes $0.2 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. (d) Includes $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs. (e) Includes the following: o $12.3 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $1.6 million of charges consisting of closure costs related to corrugated products facilities. o $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. o $0.2 million of charges for acquisition and integration costs related to recent acquisitions. (f) second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. (g) (h) o $7.2 million of income, net, primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. o $1.7 million of charges for acquisition and integration costs related to recent acquisitions. o $2.0 million gain related to the expiration of a repurchase option corresponding to timberland previously sold. o $1.6 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico. o $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. (i) (j) (k) Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing. (l) Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

Commitments, Guarantees, Inde_2

Commitments, Guarantees, Indemnifications, and Legal Proceedings (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule Of Purchase Commitments	Total purchase commitments were as follows (dollars in millions): 2020 $ 51.9 2021 47.4 2022 43.0 2023 42.8 2024 24.6 Thereafter 109.3 Total $ 319.0

Quarterly Results of Operatio_2

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Data	2019: First (a) Second Third (b) Fourth (c) Total Net sales $ 1,733.7 $ 1,759.9 $ 1,750.7 $ 1,720.0 $ 6,964.3 Gross profit 421.4 427.9 411.4 383.3 1,644.0 Income from operations 275.4 280.4 262.8 235.1 1,053.7 Net income 186.8 193.6 179.8 136.2 696.4 Basic earnings per share 1.98 2.05 1.90 1.44 7.36 Diluted earnings per share 1.97 2.04 1.89 1.43 7.34 Stock price - high 101.84 103.80 109.37 114.78 114.78 Stock price - low 81.87 87.85 96.30 100.54 81.87 2018: First (d) Second (e) Third (f) Fourth (g) Total Net sales $ 1,690.6 $ 1,767.5 $ 1,809.9 $ 1,746.6 $ 7,014.6 Gross profit 356.1 420.6 443.2 425.4 1,645.3 Income from operations 212.9 269.6 298.5 286.7 1,067.7 Net income 140.1 186.6 206.7 204.6 738.0 Basic earnings per share 1.48 1.98 2.19 2.17 7.82 Diluted earnings per share 1.48 1.97 2.18 2.16 7.80 Stock price - high 131.13 124.70 118.88 110.62 131.13 Stock price - low 109.04 107.96 107.39 77.90 77.90 Note: The sum of the quarters may not equal the total of the respective year's earnings per share on either a basic or diluted basis due to changes in the weighted average shares outstanding throughout the year. (a) Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share). (b) Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share). (c) Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share). (d ) Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share). (e ) Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share). (f ) Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share). (g ) Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

Nature of Operations and Basi_2

Nature of Operations and Basis of Presentation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019employeeSegment
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Date of incorporation	Jan. 25, 1999
Number of employees of PCA | employee	15,500
Number of reportable segments | Segment	3

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
		Dec. 31, 2019USD ($)a	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)		Jan. 01, 2019USD ($)
Summary of Significant Accounting Policies [Line Items]
Research and development costs		$ 16,000,000	$ 14,400,000	$ 12,800,000
Cash and cash equivalents		679,500,000	361,500,000
Cash equivalents		410,700,000	311,100,000
Other-than-temporary impairment charges on available-for-sale securities		0
Marketable debt securities			0
Allowance for doubtful accounts		$ 4,200,000	4,600,000
Customer returns, allowances and earned discounts as a percentage of gross selling price		1.00%
Reserve for customer accounts receivable, percentage		1.00%
Reserve for customer deductions		$ 8,400,000	9,000,000
Interest capitalization, construction in progress		3,400,000	4,500,000	2,500,000
Depreciation expense		346,800,000	361,700,000	347,800,000
Incremental depreciation		$ 300,000	$ 14,500,000	10,500,000
Intangible asset, useful life, in years		9 years 10 months 24 days	10 years 9 months 18 days
Goodwill		$ 918,700,000	$ 917,300,000	883,200,000	[1],[2]
Goodwill and intangible asset impairment		0	0	0
Deferred financing costs		$ 16,300,000	12,600,000
Area leased under timberland cutting rights (acres) | a		73,000
Area leased where fiber farms are operated (acres) | a		3,000
Net loss on impairment of assets			3,100,000	13,500,000
Depletion expense		$ 2,700,000	7,600,000	5,200,000
Software amortization expense		900,000	2,100,000	$ 2,300,000
Operating lease liabilities		240,200,000
Other long-term assets
Summary of Significant Accounting Policies [Line Items]
Long-term lease costs capitalization (Cutting rights)		21,600,000	22,400,000
Net capitalized software costs		1,400,000	1,600,000
Adjustments for New Accounting Pronouncement | Long-term debt
Summary of Significant Accounting Policies [Line Items]
Deferred financing costs		$ 16,300,000	$ 12,600,000
ASU 2016-02
Summary of Significant Accounting Policies [Line Items]
Operating lease liabilities						$ 228,000,000
Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years	[3],[4]	10 years	10 years 10 months 24 days
Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years	[4]	9 years 6 months	10 years 1 month 6 days
Minimum
Summary of Significant Accounting Policies [Line Items]
Term of senior credit facilities and notes, in years		10 years
Minimum | Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years		10 years
Minimum | Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years		5 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Term of senior credit facilities and notes, in years		30 years
Maximum | Customer Relationships
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years		40 years
Maximum | Trademarks and Trade Names
Summary of Significant Accounting Policies [Line Items]
Intangible asset, useful life, in years		20 years
Foreign operations
Summary of Significant Accounting Policies [Line Items]
Cash and cash equivalents		$ 2,400,000	$ 2,300,000
[1]	During 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container
[2]	In connection with the October 2018 acquisition of Englander, the Company recorded $28.6 million of goodwill in the Packaging segment in 2018.
[3]	During 2019, a corrugated products facility sold part of its operations which included existing inventory, certain production equipment, and customer relationships corresponding to the operations sold. As a result, the gross carrying amount for the customer relationships intangible asset was decreased by $0.7 million.
[4]	In connection with the October 2018 acquisition of Englander, the Company recorded intangible assets of $13.2 million for customer relationships, $0.8 million for trade names, and $0.1 million for other intangibles

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Components of Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 271.5	$ 307.8
Work in process	11	13.9
Finished goods	207.7	199
Supplies and materials	303.9	274.9
Inventories	$ 794.1	$ 795.6

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property, plant and equipment, at cost	$ 6,997.8	$ 6,691.1
Less accumulated depreciation	(3,846.1)	(3,582.5)
Property, plant and equipment, net	3,151.7	3,108.6
Land and Land Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, at cost	177.5	161.9
Buildings
Property Plant And Equipment [Line Items]
Property, plant and equipment, at cost	837.4	795.5
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, at cost	5,727.4	5,481.6
Construction in Progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, at cost	174	176.7
Other
Property Plant And Equipment [Line Items]
Property, plant and equipment, at cost	$ 81.5	$ 75.4

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2019
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated useful life of asset, description	Period of the lease or useful life, if shorter
Minimum | Buildings And Land Improvements
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	5 years
Minimum | Machinery and Equipment
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	3 years
Minimum | Trucks and Automobiles
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	3 years
Minimum | Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	3 years
Minimum | Computers and Hardware
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	3 years
Maximum | Buildings And Land Improvements
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	40 years
Maximum | Machinery and Equipment
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	25 years
Maximum | Trucks and Automobiles
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	10 years
Maximum | Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	20 years
Maximum | Computers and Hardware
Property Plant And Equipment [Line Items]
Estimated useful life of asset (in years)	10 years

Leases - Additional Information

Leases - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019USD ($)Lease	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Leases [Line Items]
Number of leases | Lease	2
Lease term	12 months
Finance lease obligations	$ 17,500,000	$ 19,000,000
Total lease expense		115,100,000	$ 100,600,000
Sublease rental income		0	0
Interest paid, finance lease obligations		1,300,000	$ 1,400,000
Buildings Machinery and Equipment
Leases [Line Items]
Finance lease obligations	$ 17,500,000	$ 19,000,000
Real Estate Leases | Minimum
Leases [Line Items]
Lease renewal term	1 year
Real Estate Leases | Maximum
Leases [Line Items]
Lease renewal term	5 years

Schedule of Supplemental Balanc

Schedule of Supplemental Balance Sheet Information Related to Operating Leases (Details) $ in Millions	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease right-of-use assets	$ 234.3
Current portion of operating lease obligations	62.6
Long-term portion of operating lease obligations	177.6
Total operating lease obligations	$ 240.2

Schedule of Supplemental Bala_2

Schedule of Supplemental Balance Sheet Information Related to Finance Leases (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Leases [Line Items]
Total	$ 6,997.8	$ 6,691.1
Less accumulated amortization	(3,846.1)	(3,582.5)
Property, plant and equipment, net	3,151.7	3,108.6
Current portion of finance lease obligations	1.5	1.4
Long-term portion of finance lease obligations	16	17.6
Total finance lease obligations	17.5	19
Buildings
Leases [Line Items]
Total	837.4	795.5
Machinery and Equipment
Leases [Line Items]
Total	5,727.4	5,481.6
Finance Leases
Leases [Line Items]
Total	28.8	28.8
Less accumulated amortization	(18.1)	(16.7)
Property, plant and equipment, net	10.7	12.1
Finance Leases | Buildings
Leases [Line Items]
Total	0.3	0.3
Finance Leases | Machinery and Equipment
Leases [Line Items]
Total	$ 28.5	$ 28.5

Schedule of Weighted Average Re

Schedule of Weighted Average Remaining Lease Term and Weighted Average Discount Rates for Leases (Details)	Dec. 31, 2019
Weighted-average remaining lease term (years):
Operating leases	5 years 7 months 6 days
Finance leases	8 years 9 months 18 days
Weighted-average discount rate:
Operating leases	4.23%
Finance leases	6.66%

Components of Lease Expense (De

Components of Lease Expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Finance lease cost:
Amortization of finance lease assets	$ 1.5
Interest on lease liabilities	1.2
Total finance lease cost	2.7
Operating lease cost	70.2
Short-term lease cost	19.2
Variable lease cost	13.7
Total lease cost	$ 105.8

Schedule of Supplemental Cash F

Schedule of Supplemental Cash Flow Information Related to Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ (60)
Operating cash flows for finance leases	(1.5)
Financing cash flows for finance leases	(1.2)
Right-of-use assets obtained in exchange for new lease obligations:
Operating leases	(27.7)
Supplemental non-cash information on changes in lease liabilities	44.5
Supplemental non-cash information on changes in right-of-use assets	$ 21.4

Schedule of Future Minimum Paym

Schedule of Future Minimum Payments Under Operating and Finance Lease Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Operating leases
2020		$ 71.2
2021		60.6
2022		42.8
2023		28.7
2024		20.2
Thereafter		48
Total lease payments		271.5
Less imputed interest	[1]	(31.3)
Present value of lease liabilities		240.2
Finance leases
2020		2.7
2021		2.7
2022		2.7
2023		2.7
2024		2.7
Thereafter		9.7
Total lease payments		23.2
Less imputed interest	[1]	(5.7)
Present value of lease liabilities		$ 17.5	$ 19
[1]	Calculated using the incremental borrowing rate for each lease applied to the future payments.

Schedule of Future Minimum Pa_2

Schedule of Future Minimum Payments Under Operating and Finance Lease Liabilities Under ASC 840 (Details) $ in Millions	Dec. 31, 2018USD ($)
Operating Leases
2019	$ 70.1
2020	58.7
2021	47.4
2022	29.9
2023	17.8
Thereafter	46.4
Total lease payments	270.3
Finance Leases
2019	2.7
2020	2.7
2021	2.7
2022	2.7
2023	2.7
Thereafter	12.4
Total lease payments	25.9
Less imputed interest	(6.9)	[1]
Present value of lease liabilities	$ 19
[1]	Calculated using the incremental borrowing rate for each lease applied to the future payments.

Revenue - Summary of Revenues D

Revenue - Summary of Revenues Disaggregated by Product Line (Details) - USD ($) $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2019

[1]

Sep. 30, 2019

[2]

Jun. 30, 2019

Mar. 31, 2019

[3]

Dec. 31, 2018

[4]

Sep. 30, 2018

[5]

Jun. 30, 2018

[6]

Mar. 31, 2018

[7]

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

[8]

Disaggregation Of Revenue [Line Items]

Revenue

$ 1,720

$ 1,750.7

$ 1,759.9

$ 1,733.7

$ 1,746.6

$ 1,809.9

$ 1,767.5

$ 1,690.6

$ 6,964.3

$ 7,014.6

$ 6,444.9

Packaging

Disaggregation Of Revenue [Line Items]

Revenue

5,932.2

5,938.5

5,312.3

Paper

Disaggregation Of Revenue [Line Items]

Revenue

964.3

1,002

1,051.8

Corporate and Other

Disaggregation Of Revenue [Line Items]

Revenue

$ 67.8

$ 74.1

$ 80.8

[1]

Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).

[2]

Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).

[3]

Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).

[4]

Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

[5]

Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).

[6]

Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).

[7]

Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).

[8]

2017 has not been adjusted under the modified retrospective method for Topic 606.

Revenue - Additional Informatio

Revenue - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019
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. 09, 2018	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Cash purchase price				$ 56.3	$ 273.8
Englander
Business Acquisition [Line Items]
Acquisition completion date	Oct. 9, 2018
Cash purchase price	$ 56.3
Goodwill	28.6
Intangible assets	$ 14.1
Acquired finite-lived intangible assets, weighted average useful life	9 years 8 months 12 days
Adjustment to seller related to a final working capital		$ 1.4	$ 1.4
Increase in purchase price as result of increase in goodwill adjustments		$ 57.7

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															12 Months Ended
	Dec. 31, 2019	[1]	Sep. 30, 2019	[2]	Jun. 30, 2019	Mar. 31, 2019	[3]	Dec. 31, 2018	[4]	Sep. 30, 2018	[5]	Jun. 30, 2018	[6]	Mar. 31, 2018	[7]	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income	$ 136.2		$ 179.8		$ 193.6	$ 186.8		$ 204.6		$ 206.7		$ 186.6		$ 140.1		$ 696.4	$ 738	$ 668.6
Less: distributed and undistributed earnings allocated to participating securities																(5.2)	(5.7)	(5.6)
Net income attributable to common stockholders																$ 691.2	$ 732.3	$ 663
Denominator:
Weighted average common shares outstanding (in shares)																93.8	93.7	93.5
Effect of dilutive securities (in shares)																0.3	0.2	0.2
Diluted common shares outstanding (in shares)																94.1	93.9	93.7
Basic income per common share (in dollars per share)	$ 1.44		$ 1.90		$ 2.05	$ 1.98		$ 2.17		$ 2.19		$ 1.98		$ 1.48		$ 7.36	$ 7.82	$ 7.09
Diluted income per common share (in dollars per share)	$ 1.43		$ 1.89		$ 2.04	$ 1.97		$ 2.16		$ 2.18		$ 1.97		$ 1.48		$ 7.34	$ 7.80	$ 7.07
[1]	Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).
[2]	Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).
[3]	Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).
[4]	Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act
[5]	Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).
[6]	Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).
[7]	Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).

Other (Expense) Income, Net - C

Other (Expense) Income, Net - Components of Other (Expense) Income, Net (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs	[1]	$ (25)	$ (17.3)	$ (10.5)
Facilities closure and other costs	[2]	(0.3)	(1.6)	5.9
Insurance deductible for property damage	[3]		(0.5)
Acquisition and integration related costs	[4]		(0.2)	(0.8)
Hexacomb working capital adjustment	[5]			2.3
Expiration of timberland repurchase option	[6]			2
Other		(6.7)	(6.7)	(3.9)
Total		(32.7)	(41.2)	(18.4)
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[7]	$ (0.7)	$ (14.9)	(23.1)
DeRidder, Louisiana Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
DeRidder mill incident	[8]			$ 9.7
[1]	For 2019, includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill.
[2]	For 2019, includes charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility. For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes income primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, a paper administration facility, a corporate administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities.
[3]	Includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities.
[4]	Includes charges for acquisition and integration costs related to recent acquisitions.
[5]	Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.
[6]	Includes a gain related to the expiration of a repurchase option corresponding to timberland previously sold.
[7]	Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to produce virgin kraft linerboard.
[8]	Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill.

Other (Expense) Income, Net -_2

Other (Expense) Income, Net - Components of Other (Expense) Income, Net (Parenthetical) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
DeRidder, Louisiana Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Charges for disposal of fixed assets	$ 3

Income Taxes - Components of Co

Income Taxes - Components of Consolidated Income Tax Provision (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income tax provision (benefit) -
U.S. federal	$ 123.2	$ 150.7	$ 209.3
State and local	37	42.9	34.9
Foreign	0.1	0.2	0.3
Total current provision for taxes	160.3	193.8	244.5
Deferred -
U.S. federal	55.3	34.7	(90.2)
State and local	5	4	5.7
Total deferred provision (benefit) for taxes	60.3	38.7	(84.5)
Total provision for taxes	$ 220.6	$ 232.5	$ 160

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Federal corporate tax rate			21.00%	21.00%	35.00%
Maximum measurement period to finalize accounting of tax			1 year
Income tax benefit as result of Tax Act	$ 2	$ 122.1
Re-measurement of deferred tax assets and liabilities due to enacted corporate tax rate					$ 128
Reduction in domestic manufacturers deductions					5.1
Transition tax due to tax reform					0.8
Cash payments for income taxes			$ 172.7	$ 140.8	298.7
Gross reserve for unrecognized tax benefits, excluding interest and penalties	4.6	$ 4.8	4.8	4.6	$ 4.8	$ 5.2
Unrecognized tax benefits that would impact of effective tax rate			4.2
Interest accrued related to unrecognized tax benefits and penalties	$ 1.1		1.2	$ 1.1
Reasonably possible decrease in unrecognized tax benefits related to state apportionment issues in next 12 months			$ 3.1
Boise Inc.
Income Taxes [Line Items]
Open tax year			2008 2009 2010 2011 2012 2013
Foreign
Income Taxes [Line Items]
Open tax year			2009
State taxing jurisdiction
Income Taxes [Line Items]
Open tax year			2015 2016 2017 2018 2019
Internal Revenue Service (IRS)
Income Taxes [Line Items]
Income tax examination (description)			A federal examination of the 2016 tax year commenced in April 2019.
Open tax year			2016 2017 2018 2019

Income Taxes - Summary of Effec

Income Taxes - Summary of Effective Tax Rate (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provision computed at U.S. federal statutory rate	[1]	$ 192.6	$ 203.8	$ 290
Federal tax reform			(2)	(127.2)
State and local taxes, net of federal benefit		35.7	36.9	24
Domestic manufacturers deduction	[2]			(21.1)
Other		(7.7)	(6.2)	(5.7)
Total provision for taxes		$ 220.6	$ 232.5	$ 160
[1]	U.S. federal statutory rate of 21%
[2]	The domestic manufacturers deduction was eliminated after 2017 as a result of the Tax Cuts and Jobs Act.

Income Taxes - Summary of Eff_2

Income Taxes - Summary of Effective Tax Rate (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. Federal statutory rate	21.00%	21.00%	35.00%

Income Taxes - Details of Sched

Income Taxes - Details of Scheduled Expiration Dates of Tax Effected Net Operating Loss (NOL) and Other Tax Carryforwards (Details) $ in Millions	Dec. 31, 2019USD ($)
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Total	$ 34
U.S. federal
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Net Operating Loss	29
U.S. federal tax credit carryforwards	0.1
State taxing jurisdiction
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Net Operating Loss	1.8
U.S. federal and non-U.S.
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
U.S. federal and non-U.S. capital loss carryforwards	3.1
2020 Through 2029
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Total	33.7
2020 Through 2029 | U.S. federal
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Net Operating Loss	29
U.S. federal tax credit carryforwards	0.1
2020 Through 2029 | State taxing jurisdiction
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Net Operating Loss	1.6
2020 Through 2029 | U.S. federal and non-U.S.
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
U.S. federal and non-U.S. capital loss carryforwards	3
2030 Through 2039
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Total	0.2
2030 Through 2039 | State taxing jurisdiction
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Net Operating Loss	0.2
Indefinite
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
Total	0.1
Indefinite | U.S. federal and non-U.S.
Operating Loss Carryforwards And Other Tax Carryforwards [Line Items]
U.S. federal and non-U.S. capital loss carryforwards	$ 0.1

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Pension and postretirement benefits		$ 90.7	$ 87.4
Lease obligations		59.2
Employee benefits and compensation		35.5	37.7
Net operating loss carryforwards		30.8	34.4
Inventories		14.1	12.6
Restricted stock and performance units		11.2	10.2
Accrued liabilities		6.1	17.1
Capital loss and general business credit carryforwards		3.2	3.3
Derivatives		0.1	4.7
Gross deferred tax assets		250.9	207.4
Valuation allowance	[1]	(3)	(3.1)
Net deferred tax assets		247.9	204.3
Deferred tax liabilities:
Property, plant and equipment		(459.1)	(422.3)
Goodwill and intangible assets		(70.8)	(67.2)
Right-of-use assets		(58.1)
Total deferred tax liabilities		(588)	(489.5)
Net deferred tax liabilities	[2]	$ (340.1)	$ (285.2)
[1]	Deferred tax assets are reduced by a valuation allowance when it is more likely than not that some portion of the deferred tax assets will not be realized. Both the 2019 and 2018 valuation allowance relates to capital losses. We do not expect to generate capital gains before the capital losses expire. If or when recognized, the tax benefits relating to the reversal of any or all of the valuation allowance would be recognized as a benefit to income tax expense.
[2]	As of December 31, 2019, we did not recognize U.S. deferred income taxes on our cumulative total of undistributed foreign earnings for our foreign subsidiaries. We indefinitely reinvest our earnings in operations outside the United States. It is not practicable to determine the amount of unrecognized deferred tax liability on these undistributed earnings because the actual tax liability, if any, is dependent on circumstances existing when the repatriation occurs.

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes Related to PCAs Gross Unrecognized Tax Benefits Excluding Interest and Penalties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Balance as of January 1	$ (4.6)	$ (4.8)	$ (5.2)
Increases related to prior years’ tax positions	(0.1)	(0.1)
Increases related to current year tax positions	(0.4)	(0.3)	(0.4)
Expiration of the statute of limitations	0.3	0.6	0.8
Balance at December 31	$ (4.8)	$ (4.6)	$ (4.8)

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets -Goodwill - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	[1],[2]
Goodwill [Line Items]
Goodwill	$ 918.7	$ 917.3	$ 883.2
Packaging
Goodwill [Line Items]
Goodwill	863.5	862.1	828
Paper
Goodwill [Line Items]
Goodwill	$ 55.2	$ 55.2	$ 55.2
[1]	During 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container
[2]	In connection with the October 2018 acquisition of Englander, the Company recorded $28.6 million of goodwill in the Packaging segment in 2018.

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Oct. 31, 2018	Dec. 31, 2019		Dec. 31, 2018
Goodwill [Line Items]
Beginning Balance			$ 917.3		$ 883.2	[1],[2]
Ending Balance			918.7		917.3
Sacramento Container and Englander
Goodwill [Line Items]
Acquisitions					34.1
Englander
Goodwill [Line Items]
Acquisitions	[3]		1.4
Packaging
Goodwill [Line Items]
Beginning Balance			862.1		828	[1],[2]
Ending Balance			863.5		862.1
Packaging | Sacramento Container and Englander
Goodwill [Line Items]
Acquisitions					34.1
Packaging | Englander
Goodwill [Line Items]
Acquisitions		$ 28.6	1.4	[3]
Paper
Goodwill [Line Items]
Beginning Balance			55.2		55.2	[1],[2]
Ending Balance			$ 55.2		$ 55.2
[1]	During 2018, the Company recorded a $5.5 million adjustment to increase the goodwill balance for the Company’s October 2017 acquisition of Sacramento Container
[2]	In connection with the October 2018 acquisition of Englander, the Company recorded $28.6 million of goodwill in the Packaging segment in 2018.
[3]	During 2019, the Company recorded a $1.4 million adjustment to increase the goodwill balance for the Company’s October 2018 acquisition of Englander.

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Goodwill (Parenthetical) (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended	12 Months Ended
		Oct. 31, 2018	Jun. 30, 2019	Dec. 31, 2019		Dec. 31, 2018
Sacramento Container Corporation
Goodwill [Line Items]
Increase to goodwill, acquisition adjustment						$ 5.5
Englander
Goodwill [Line Items]
Increase to goodwill, acquisition adjustment			$ 1.4	$ 1.4
Acquisitions	[1]			1.4
Englander | Packaging
Goodwill [Line Items]
Acquisitions		$ 28.6		$ 1.4	[1]
[1]	During 2019, the Company recorded a $1.4 million adjustment to increase the goodwill balance for the Company’s October 2018 acquisition of Englander.

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Components of Intangible Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)		9 years 10 months 24 days	10 years 9 months 18 days
Gross Carrying Amount		$ 542.9	$ 543.7
Accumulated Amortization		$ 204.1	$ 165.5
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	[1],[2]	10 years	10 years 10 months 24 days
Gross Carrying Amount	[1],[2]	$ 503.8	$ 504.6
Accumulated Amortization	[1],[2]	$ 180.2	$ 144.5
Trademarks and Trade Names
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	[2]	9 years 6 months	10 years 1 month 6 days
Gross Carrying Amount	[2]	$ 34.8	$ 34.8
Accumulated Amortization	[2]	$ 20.6	$ 18.3
Other Intangible Assets
Finite Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life (in Years)	[2]	2 years 1 month 6 days	3 years
Gross Carrying Amount	[2]	$ 4.3	$ 4.4
Accumulated Amortization	[2]	$ 3.3	$ 2.7
[1]	During 2019, a corrugated products facility sold part of its operations which included existing inventory, certain production equipment, and customer relationships corresponding to the operations sold. As a result, the gross carrying amount for the customer relationships intangible asset was decreased by $0.7 million.
[2]	In connection with the October 2018 acquisition of Englander, the Company recorded intangible assets of $13.2 million for customer relationships, $0.8 million for trade names, and $0.1 million for other intangibles

Goodwill and Intangible Asset_6

Goodwill and Intangible Assets - Components of Intangible Assets (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Oct. 31, 2018
Customer Relationships
Goodwill [Line Items]
Increase (decrease) in acquired intangible assets	$ 0.7
Customer Relationships | Englander
Goodwill [Line Items]
Other intangible assets		$ 13.2
Trademarks and Trade Names | Englander
Goodwill [Line Items]
Other intangible assets		0.8
Other Intangible Assets | Englander
Goodwill [Line Items]
Other intangible assets		$ 0.1

Goodwill and Intangible Asset_7

Goodwill and Intangible Assets - Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible assets amortization expense	$ 38.6	$ 40.5	$ 35.7
2020	38.7
2021	37.9
2022	35.4
2023	34.4
2024	$ 33.9

Accrued Liabilities - Component

Accrued Liabilities - Components of Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Compensation and benefits	$ 124.5	$ 136.7
Customer volume discounts and rebates	27.9	25.2
Medical insurance and workers’ compensation	26.3	27.5
Franchise, property, sales and use taxes	15.3	13.4
Environmental liabilities and asset retirement obligations	5.6	5
Severance, retention, and relocation	3.5	2.2
Other	14.4	12.4
Total	$ 217.5	$ 222.4

Debt - Summary of Debt (Details

Debt - Summary of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 23, 2019	Dec. 06, 2019	Nov. 21, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 13, 2017	Sep. 05, 2014	Oct. 22, 2013	Jun. 26, 2012
Debt Instrument [Line Items]
Long-term debt	$ 2,493.1				$ 2,496.3
Less current portion	0				0
Less unamortized debt issuance costs	16.3				12.6
Long-term debt	$ 2,476.8				$ 2,483.7
Weighted-average interest rate	3.77%				3.64%
Revolving Credit Facility, due August 2021 | Line of Credit
Debt Instrument [Line Items]
Long-term debt	$ 0				$ 0
Stated interest rate	0.00%				0.00%
2.45% Senior Notes, due December 2020
Debt Instrument [Line Items]
Stated interest rate	2.45%					2.45%
2.45% Senior Notes, due December 2020 | Senior Notes
Debt Instrument [Line Items]
Long-term debt					$ 499.6
Stated interest rate			2.45%	2.45%	2.45%		2.45%
3.90% Senior Notes, due June 2022
Debt Instrument [Line Items]
Stated interest rate	3.90%
3.90% Senior Notes, due June 2022 | Senior Notes
Debt Instrument [Line Items]
Long-term debt					$ 399.9
Stated interest rate		3.90%		3.90%	3.90%					3.90%
4.50% Senior Notes, due November 2023 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 699.2				$ 699
Stated interest rate	4.50%				4.50%				4.50%
3.65% Senior Notes, due September 2024 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 399.4				$ 399.3
Stated interest rate	3.65%				3.65%			3.65%
3.40% Senior Notes, due December 2027
Debt Instrument [Line Items]
Stated interest rate						3.40%
3.40% Senior Notes, due December 2027 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 498.7				$ 498.5
Stated interest rate	3.40%				3.40%		3.40%
3.00% Senior Notes, due December 2029
Debt Instrument [Line Items]
Stated interest rate	3.00%
3.00% Senior Notes, due December 2029 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 499.3
Stated interest rate	3.00%			3.00%
4.05% Senior Notes, due December 2049
Debt Instrument [Line Items]
Stated interest rate	4.05%
4.05% Senior Notes, due December 2049 | Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 396.5
Stated interest rate	4.05%			4.05%
Current Portion of Long-term Debt
Debt Instrument [Line Items]
Weighted-average interest rate	0.00%				0.00%
Long-term Debt, Excluding Current Portion
Debt Instrument [Line Items]
Weighted-average interest rate	3.77%				3.64%

Debt - Summary of Debt (Parenth

Debt - Summary of Debt (Parenthetical) (Details) - USD ($) $ in Millions	Nov. 21, 2019	Dec. 13, 2017	Sep. 05, 2014	Oct. 22, 2013	Jun. 26, 2012	Dec. 31, 2019	Dec. 31, 2018	Dec. 23, 2019	Dec. 06, 2019	Dec. 31, 2017
Revolving Credit Facility, due August 2021 | Line of Credit
Debt Instrument [Line Items]
Credit facility, expiration date						Aug. 21, 2021	Aug. 21, 2021
Stated interest rate						0.00%	0.00%
2.45% Senior Notes, due December 2020
Debt Instrument [Line Items]
Stated interest rate						2.45%				2.45%
2.45% Senior Notes, due December 2020 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate	2.45%	2.45%					2.45%		2.45%
Senior notes, discount							$ 0.4
Debt instrument, maturity date	Dec. 15, 2020	Dec. 15, 2020					Dec. 15, 2020
3.90% Senior Notes, due June 2022
Debt Instrument [Line Items]
Stated interest rate						3.90%
3.90% Senior Notes, due June 2022 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate	3.90%				3.90%		3.90%	3.90%
Senior notes, discount							$ 0.1
Debt instrument, maturity date	Jun. 15, 2022				Jun. 15, 2022		Jun. 15, 2022
4.50% Senior Notes, due November 2023 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate				4.50%		4.50%	4.50%
Senior notes, discount						$ 0.8	$ 1
Debt instrument, maturity date				Nov. 1, 2023		Nov. 1, 2023	Nov. 1, 2023
3.65% Senior Notes, due September 2024 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate			3.65%			3.65%	3.65%
Senior notes, discount						$ 0.6	$ 0.7
Debt instrument, maturity date			Sep. 15, 2024			Sep. 15, 2024	Sep. 15, 2024
3.40% Senior Notes, due December 2027
Debt Instrument [Line Items]
Stated interest rate										3.40%
3.40% Senior Notes, due December 2027 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate		3.40%				3.40%	3.40%
Senior notes, discount						$ 1.3	$ 1.5
Debt instrument, maturity date		Dec. 15, 2027				Dec. 15, 2027	Dec. 15, 2027
3.00% Senior Notes, due December 2029
Debt Instrument [Line Items]
Stated interest rate						3.00%
3.00% Senior Notes, due December 2029 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate	3.00%					3.00%
Senior notes, discount						$ 0.7
Debt instrument, maturity date	Dec. 15, 2029					Dec. 15, 2029
4.05% Senior Notes, due December 2049
Debt Instrument [Line Items]
Stated interest rate						4.05%
4.05% Senior Notes, due December 2049 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate	4.05%					4.05%
Senior notes, discount						$ 3.5
Debt instrument, maturity date	Dec. 15, 2049					Dec. 15, 2049

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	Dec. 23, 2019	Dec. 06, 2019	Nov. 21, 2019	Dec. 13, 2017	Sep. 05, 2014	Oct. 22, 2013	Jun. 26, 2012	Nov. 30, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 18, 2013
Annual Principal Maturities for Debt [Abstract]
2020									$ 0	$ 0
2021									0	0
2022									0	0
2023									700,000,000	700,000,000
2024 and thereafter									1,800,000,000	1,800,000,000
Interest payments										114,000,000	$ 97,000,000	$ 96,300,000
Amortization of net (loss) gain on treasury lock										(18,200,000)	(5,300,000)	(5,700,000)
Amortization of financing costs										4,500,000	$ 2,700,000	4,000,000
Write-off of deferred debt issuance costs								$ 1,800,000				$ 1,800,000
Treasury Lock
Annual Principal Maturities for Debt [Abstract]
Amortization of net (loss) gain on treasury lock								$ (13,100,000)	(13,100,000)
Senior Notes
Debt Instrument [Line Items]
Debt issuance costs										8,300,000
Unsecured Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Debt, face amount													$ 1,650,000,000
Line of Credit
Debt Instrument [Line Items]
Credit facility borrowing capacity													$ 350,000,000
Unused borrowing capacity									329,200,000	329,200,000
Line of Credit | Letter of Credit
Debt Instrument [Line Items]
Outstanding letters of credit									$ 20,800,000	$ 20,800,000
3.00% Senior Notes, due December 2029
Debt Instrument [Line Items]
Stated interest rate									3.00%	3.00%
3.00% Senior Notes, due December 2029 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount			$ 500,000,000
Stated interest rate			3.00%						3.00%	3.00%
Debt instrument, maturity date			Dec. 15, 2029							Dec. 15, 2029
4.05% Senior Notes, due December 2049
Debt Instrument [Line Items]
Stated interest rate									4.05%	4.05%
4.05% Senior Notes, due December 2049 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount			$ 400,000,000
Stated interest rate			4.05%						4.05%	4.05%
Debt instrument, maturity date			Dec. 15, 2049							Dec. 15, 2049
2.45% Senior Notes, due December 2020
Debt Instrument [Line Items]
Stated interest rate									2.45%	2.45%		2.45%
Debt instrument, redemption amount included premiums, accrued and unpaid interest									$ 509,700,000	$ 509,700,000
2.45% Senior Notes, due December 2020 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount			$ 500,000,000	$ 500,000,000
Stated interest rate		2.45%	2.45%	2.45%							2.45%
Debt instrument, maturity date			Dec. 15, 2020	Dec. 15, 2020							Dec. 15, 2020
Debt instrument, redemption amount		$ 509,700,000
Debt instrument, redemption premium		3,800,000
Debt instrument, accrued and unpaid interest		$ 5,800,000
3.90% Senior Notes, due June 2022
Debt Instrument [Line Items]
Stated interest rate									3.90%	3.90%
Debt instrument, redemption amount included premiums, accrued and unpaid interest									$ 418,700,000	$ 418,700,000
3.90% Senior Notes, due June 2022 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount			$ 400,000,000				$ 400,000,000
Stated interest rate	3.90%		3.90%				3.90%				3.90%
Debt instrument, maturity date			Jun. 15, 2022				Jun. 15, 2022				Jun. 15, 2022
Debt instrument, redeem date			2019-12
Debt instrument, redemption amount	$ 418,700,000
Debt instrument, redemption premium	18,400,000
Debt instrument, accrued and unpaid interest	$ 300,000
4.50% Senior Notes, due November 2023 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount						$ 700,000,000
Stated interest rate						4.50%			4.50%	4.50%	4.50%
Debt instrument, maturity date						Nov. 1, 2023				Nov. 1, 2023	Nov. 1, 2023
3.65% Senior Notes, due September 2024 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount					$ 400,000,000
Stated interest rate					3.65%				3.65%	3.65%	3.65%
Debt instrument, maturity date					Sep. 15, 2024					Sep. 15, 2024	Sep. 15, 2024
3.40% Senior Notes, due December 2027
Debt Instrument [Line Items]
Stated interest rate												3.40%
3.40% Senior Notes, due December 2027 | Senior Notes
Debt Instrument [Line Items]
Debt, face amount				$ 500,000,000
Stated interest rate				3.40%					3.40%	3.40%	3.40%
Debt instrument, maturity date				Dec. 15, 2027						Dec. 15, 2027	Dec. 15, 2027
Fixed-Rate Senior Notes | Senior Notes
Debt Instrument [Line Items]
Book value of fixed rate debt									$ 2,493,100,000	$ 2,493,100,000
Long-term debt (fixed-rate debt), fair value									$ 2,616,200,000	2,616,200,000
6.50% Senior Notes due March 2018 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate											6.50%
Debt instrument, maturity date											Mar. 15, 2018
Repayment of debt											$ 150,000,000
Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Repayment of debt												$ 1,000,000,000
Redemption Premiums
Annual Principal Maturities for Debt [Abstract]
Interest payments										$ 22,200,000

Cash, Cash Equivalents, and M_3

Cash, Cash Equivalents, and Marketable Debt Securities - Schedule of Company's Cash and Available-For-Sale (AFS) Debt Securities by Major Asset Category (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Financial Instruments [Line Items]
Adjusted Cost Basis		$ 825.5
Fair Value	[1]	825.5
Cash and cash equivalents		679.5	$ 361.5
Short-term marketable debt securities		87.9
Long-term marketable debt securities		58.1
Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	27.2
Fair Value	[1],[2]	27.2
Cash and cash equivalents	[2]	3.2
Short-term marketable debt securities	[2]	11.5
Long-term marketable debt securities	[2]	12.5
Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[3]	122.7
Fair Value	[1],[3]	122.7
Cash and cash equivalents	[3]	0.7
Short-term marketable debt securities	[3]	76.4
Long-term marketable debt securities	[3]	45.6
Cash and Cash Equivalents
Financial Instruments [Line Items]
Adjusted Cost Basis		675.6
Fair Value	[1]	675.6
Cash and cash equivalents		675.6
Money Market Fund | Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	0.1
Fair Value	[1],[2]	0.1
Cash and cash equivalents	[2]	0.1
U.S. Treasury Securities | Level 1
Financial Instruments [Line Items]
Adjusted Cost Basis	[2]	27.1
Fair Value	[1],[2]	27.1
Cash and cash equivalents	[2]	3.1
Short-term marketable debt securities	[2]	11.5
Long-term marketable debt securities	[2]	12.5
Certificates of Deposit | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[3]	3.9
Fair Value	[1],[3]	3.9
Short-term marketable debt securities	[3]	3.9
Commercial Paper | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[3]	5.6
Fair Value	[1],[3]	5.6
Cash and cash equivalents	[3]	0.7
Short-term marketable debt securities	[3]	4.9
U.S. Government Agency Securities | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[3]	7
Fair Value	[1],[3]	7
Short-term marketable debt securities	[3]	3
Long-term marketable debt securities	[3]	4
Corporate Debt Securities | Level 2
Financial Instruments [Line Items]
Adjusted Cost Basis	[3]	106.2
Fair Value	[1],[3]	106.2
Short-term marketable debt securities	[3]	64.6
Long-term marketable debt securities	[3]	$ 41.6
[1]	Unrealized gains and losses were insignificant as of December 31, 2019. Therefore, the fair value approximates the adjusted cost basis for each major asset category.
[2]	Valuations based on quoted prices for identical assets or liabilities in active markets.
[3]	Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.

Cash, Cash Equivalents, and M_4

Cash, Cash Equivalents, and Marketable Debt Securities - Additional Information (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Financial Instruments [Line Items]
Marketable debt securities		$ 0
Minimum
Financial Instruments [Line Items]
Long-term marketable debt securities maturity period	1 year
Maximum
Financial Instruments [Line Items]
Long-term marketable debt securities maturity period	2 years

Cash, Cash Equivalents, and M_5

Cash, Cash Equivalents, and Marketable Debt Securities - Schedule of Market Value of Marketable Debt Securities with Continuous Unrealized Losses (Details) - Fair Value of Marketable Debt Securities $ in Millions	Dec. 31, 2019USD ($)
Schedule Of Available For Sale Securities [Line Items]
Continuous Unrealized Losses, Less than 12 Months	$ 78.1
Continuous Unrealized Losses, Total	$ 78.1

Employee Benefit Plans and Ot_3

Employee Benefit Plans and Other Postretirement Benefits - Change in Benefit Obligations and Change in Fair Value of Plan Assets Related to Pension and Postretirement Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amounts Recognized on Consolidated Balance Sheets
Noncurrent liabilities		$ (375.5)	$ (357.5)
Pension Plans
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		1,204.9	1,300.2
Service cost		24.5	25	$ 23.7
Interest cost		47	42.4	41.6
Plan amendments		2.3	3
Actuarial (gain) loss	[1]	188.6	(121.1)
Participant contributions
Benefits paid		(47.2)	(44.6)
Benefit obligation at plan year end		1,420.1	1,204.9	1,300.2
Accumulated benefit obligation portion of above		1,374.4	1,163.3
Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value at beginning of period		873.2
Actual return on plan assets		188.9	(59.9)
Company contributions		58.9	22.9
Benefits paid		(47.2)	(44.6)
Fair value of plan assets at plan year end		1,073.8	873.2
Underfunded status		(346.3)	(331.7)
Amounts Recognized on Consolidated Balance Sheets
Current liabilities		(1.4)	(1.4)
Noncurrent liabilities		(344.9)	(330.3)
Accrued obligation recognized at December 31		(346.3)	(331.7)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Prior service cost (credit)		24.7	28.7
Actuarial loss (gain)		239.2	194.6
Total		263.9	223.3
Postretirement Plans
Change in Benefit Obligations [Roll Forward]
Benefit obligation at beginning of period		14.6	16.5
Service cost		0.3	0.3	0.3
Interest cost		0.5	0.5	0.6
Plan amendments		(0.3)	(0.4)
Actuarial (gain) loss	[1]	0.2	(1.2)
Participant contributions		1.1	1.1
Benefits paid		(1.9)	(2.2)
Benefit obligation at plan year end		14.5	14.6	$ 16.5
Change in Fair Value of Plan Assets [Roll Forward]
Company contributions		0.8	1.1
Participant contributions		1.1	1.1
Benefits paid		(1.9)	(2.2)
Underfunded status		(14.5)	(14.6)
Amounts Recognized on Consolidated Balance Sheets
Current liabilities		(0.7)	(0.8)
Noncurrent liabilities		(13.8)	(13.8)
Accrued obligation recognized at December 31		(14.5)	(14.6)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Prior service cost (credit)		(5.3)	(5.4)
Actuarial loss (gain)		(4.4)	(5)
Total		$ (9.7)	$ (10.4)
[1]	The actuarial loss in 2019 was due primarily to a decrease in the weighted average discount rate used to estimate pension benefit obligations. The actuarial gain in 2018 was due primarily to an increase in the weighted average discount rate used to estimate our pension benefit obligations.

Employee Benefit Plans and Ot_4

Employee Benefit Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Cost and Other Comprehensive (Income) Loss (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 24.5	$ 25	$ 23.7
Interest cost		47	42.4	41.6
Expected return on plan assets		(52.1)	(56.7)	(53.9)
Net amortization of unrecognized amounts, Prior service cost (credit)		6.3	6.9	5.8
Net amortization of unrecognized amounts, Actuarial loss (gain)		7	9.4	7.6
Net periodic benefit cost		32.7	27	24.8
Changes in plan assets and benefit obligations recognized in other comprehensive (income) loss
Actuarial net loss (gain)		51.8	(4.6)	32.2
Prior service cost (credit)		2.3	3	17.4
Amortization of prior service cost (credit)		(6.3)	(6.9)	(5.8)
Amortization of actuarial loss (gain)		(7)	(9.4)	(7.6)
Total recognized in other comprehensive loss (income)	[1]	40.8	(17.9)	36.2
Total recognized in net periodic benefit cost and other comprehensive loss (income) (pre-tax)		73.5	9.2	61
Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.3	0.3	0.3
Interest cost		0.5	0.5	0.6
Net amortization of unrecognized amounts, Prior service cost (credit)		(0.3)	(0.3)	(0.2)
Net amortization of unrecognized amounts, Actuarial loss (gain)		(0.4)	(0.2)	(0.1)
Net periodic benefit cost		0.1	0.3	0.6
Changes in plan assets and benefit obligations recognized in other comprehensive (income) loss
Actuarial net loss (gain)		0.2	(1.2)	(2.2)
Prior service cost (credit)		(0.3)	(0.3)	(0.6)
Amortization of prior service cost (credit)		0.3	0.3	0.2
Amortization of actuarial loss (gain)		0.4	0.2	0.1
Total recognized in other comprehensive loss (income)	[1]	0.6	(1)	(2.5)
Total recognized in net periodic benefit cost and other comprehensive loss (income) (pre-tax)		$ 0.7	$ (0.7)	$ (1.9)
[1]	Accumulated losses in excess of 10% of the greater of the projected benefit obligation or the market-related value of assets will be recognized on a straight-line basis over the average remaining service period of active employees in PCA plans (which is between seven and ten years) and over the average remaining lifetime of inactive participants of Boise plans (which is between 24 and 27 years), to the extent that losses are not offset by gains in subsequent years. The estimated net loss and prior service cost that will be amortized from “Accumulated other comprehensive loss” into net periodic benefit in 2020 is $14.3 million.

Employee Benefit Plans and Ot_5

Employee Benefit Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Cost and Other Comprehensive (Income) Loss (Parenthetical) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Defined Benefit Plan Disclosure [Line Items]
Accumulated losses, excess percentage threshold required on projected benefit obligation	10.00%
Estimated net periodic benefit cost for 2019	$ 14.3
Packaging Corporation of America | Minimum
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period of active employees used for recognition of market-related value of assets	7 years
Packaging Corporation of America | Maximum
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period of active employees used for recognition of market-related value of assets	10 years
Boise Inc. | Minimum
Defined Benefit Plan Disclosure [Line Items]
Average remaining lifetime of inactive participants used for recognition of market-related value of assets	24 years
Boise Inc. | Maximum
Defined Benefit Plan Disclosure [Line Items]
Average remaining lifetime of inactive participants used for recognition of market-related value of assets	27 years

Employee Benefit Plans and Ot_6

Employee Benefit Plans and Other Postretirement Benefits - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 13, 2017
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Accumulated benefit obligation for plans with obligations in excess of plan assets	$ 1,300
Weighted-Average expected return on plan assets for 2020	5.29%
Pension Contributions [Abstract]
Expected contribution to qualified plans (at least)	$ 19.8
Company's common stock	1.5	1.9
Deferred compensation liability	$ 17.4	$ 14.2
Minimum
Pension Contributions [Abstract]
Company's contribution to pension plan, percentage	3.00%
Maximum
Pension Contributions [Abstract]
Company's contribution to pension plan, percentage	5.00%
Pension Plans
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Weighted-Average expected return on plan assets for 2020	6.06%	6.06%	6.55%
Fair value of plan assets	$ 1,073.8	$ 873.2		$ 954.8
Pension Contributions [Abstract]
Contributions to pension plan	58.9	22.9
Pension Plans | Qualified
Pension Contributions [Abstract]
Contributions to pension plan	57.9	21.8	$ 42.1
Matching Contributions
Pension Contributions [Abstract]
Company's contribution to defined contribution plans	48.9	45.6	42.8
Service Related Contributions
Pension Contributions [Abstract]
Company's contribution to defined contribution plans	27.8	$ 24.5	$ 22.4
Packaging Corporation of America
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Fair value of plan assets	$ 498.8
Packaging Corporation of America | Equities
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Target Allocation	47.00%
Packaging Corporation of America | Fixed Income Securities
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Target Allocation	52.00%
Packaging Corporation of America | Other Securities
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Target Allocation	1.00%
Boise Inc.
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Fair value of plan assets	$ 575
Boise Inc. | Equities
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Target Allocation	49.00%
Boise Inc. | Fixed Income Securities
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Target Allocation	49.00%
Boise Inc. | Other Securities
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) (Pre-Tax)
Target Allocation	2.00%

Employee Benefit Plans and Ot_7

Employee Benefit Plans and Other Postretirement Benefits - Schedule of Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost, Expected return on plan assets	5.29%
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Weighted-Average Assumptions Used to Determine Benefit Obligation, Discount Rate	3.25%	4.31%	3.66%
Weighted-Average Assumptions Used to Determine Benefit Obligations, Rate of compensation increase	4.00%	4.00%	4.00%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost, Discount rate	4.31%	3.66%	4.24%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost, Expected return on plan assets	6.06%	6.06%	6.55%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost, Rate of compensation increase	4.00%	4.00%	4.00%
Postretirement Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Weighted-Average Assumptions Used to Determine Benefit Obligation, Discount Rate	3.18%	4.21%	3.55%
Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost, Discount rate	4.21%	3.57%	3.92%

Employee Benefit Plans and Ot_8

Employee Benefit Plans and Other Postretirement Benefits - Schedule of Assumed Health Care Cost Trend Rates for Postretirement Benefits (Details) - Postretirement Plans	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Health care cost trend rate assumed for next year	7.09%	7.24%	7.57%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.50%	4.44%	4.44%
Year that the rate reaches the ultimate trend rate	2029	2028	2027

Employee Benefit Plans and Ot_9

Employee Benefit Plans and Other Postretirement Benefits - Schedule of Effects of One-Percentage Point Change in Assumed Health Care Cost Trends on Postretirement Benefits (Details) - Postretirement Plans $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Effect on postretirement benefit obligation, 1-Percentage Point Decrease	$ (0.5)
Effect on postretirement benefit obligation, 1-Percentage Point Increase	0.5
Effect on net postretirement benefit cost, 1-Percentage Point Increase	$ 0.1

Employee Benefit Plans and O_10

Employee Benefit Plans and Other Postretirement Benefits - Schedule of Pension Plan Asset Investments and Target Allocations (Details)	Dec. 31, 2019	Dec. 31, 2018
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	50.00%	53.00%
International Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	27.00%	27.00%
U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	22.00%	18.00%
Other Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Fair Value	1.00%	2.00%

Employee Benefit Plans and O_11

Employee Benefit Plans and Other Postretirement Benefits - Schedule of Fair Value Measurements of Plan Assets by Major Asset Category (Details) - Pension Plans - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018	Dec. 13, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		$ 1,073.8	$ 873.2	$ 954.8
Cash and Short-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		14.9	12
International equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		286.1	238.8
Domestic equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		240.5	154.5
Government Bonds and Agencies (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		160.7
Corporate Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		70.6	64.4
Fixed Income (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		295	234.5
Municipal Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		5.8
Private Equity Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[1]	2.6	3.3
Total Securities at Fair Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		1,076.2	871.9
Accrued Expenses and Receivables
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		(2.4)	1.3
Government Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets			164.4
Quoted prices in active markets for identical assets (Level 1) | Cash and Short-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0.4
Quoted prices in active markets for identical assets (Level 1) | International equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		163	136.9
Quoted prices in active markets for identical assets (Level 1) | Domestic equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Quoted prices in active markets for identical assets (Level 1) | Government Bonds and Agencies (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0
Quoted prices in active markets for identical assets (Level 1) | Corporate Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Quoted prices in active markets for identical assets (Level 1) | Fixed Income (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		140.4	95.7
Quoted prices in active markets for identical assets (Level 1) | Municipal Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0
Quoted prices in active markets for identical assets (Level 1) | Private Equity Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[1]	0	0
Quoted prices in active markets for identical assets (Level 1) | Total Securities at Fair Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		303.4	388
Quoted prices in active markets for identical assets (Level 1) | Government Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets			155
Significant other observable inputs (Level 2) | Cash and Short-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		14.9	11.6
Significant other observable inputs (Level 2) | International equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		20.8	17.8
Significant other observable inputs (Level 2) | Domestic equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		240.5	154.5
Significant other observable inputs (Level 2) | Government Bonds and Agencies (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		160.7
Significant other observable inputs (Level 2) | Corporate Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		70.6	64.4
Significant other observable inputs (Level 2) | Fixed Income (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		154.6	138.8
Significant other observable inputs (Level 2) | Municipal Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		5.8
Significant other observable inputs (Level 2) | Private Equity Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[1]	0	0
Significant other observable inputs (Level 2) | Total Securities at Fair Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		667.9	396.5
Significant other observable inputs (Level 2) | Government Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets			9.4
Significant unobservable input (Level 3) | Cash and Short-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Significant unobservable input (Level 3) | International equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Significant unobservable input (Level 3) | Domestic equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Significant unobservable input (Level 3) | Government Bonds and Agencies (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0
Significant unobservable input (Level 3) | Corporate Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Significant unobservable input (Level 3) | Fixed Income (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0	0
Significant unobservable input (Level 3) | Municipal Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		0
Significant unobservable input (Level 3) | Private Equity Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[1]	2.6	3.3
Significant unobservable input (Level 3) | Total Securities at Fair Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets		2.6	3.3
Significant unobservable input (Level 3) | Government Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets			0
Net Asset Value (NAV) | Cash and Short-term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	0	0
Net Asset Value (NAV) | International equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	102.3	84.1
Net Asset Value (NAV) | Domestic equities (Common/Collective Trust Funds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	0	0
Net Asset Value (NAV) | Government Bonds and Agencies (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	0
Net Asset Value (NAV) | Corporate Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	0	0
Net Asset Value (NAV) | Fixed Income (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	0	0
Net Asset Value (NAV) | Municipal Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	0
Net Asset Value (NAV) | Private Equity Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[1],[2]	0	0
Net Asset Value (NAV) | Total Securities at Fair Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]	$ 102.3	84.1
Net Asset Value (NAV) | Government Bonds (Corporate and Government Bonds)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of plan assets	[2]		$ 0
[1]	Investments in this category are invested in the Pantheon Global Secondary Fund IV, LP. The fund specializes in investments in the private equity secondary market and occasionally directly in private companies to maximize capital growth. Fund investments are carried at fair value as determined quarterly using the market approach to estimate the fair value of private investments. The market approach utilizes prices and other relevant information generated by market transactions, type of security, size of the position, degree of liquidity, restrictions on the disposition, latest round of financing data, current financial position, and operating results, among other factors. In circumstances where fair values are not provided with respect to any of the company's fund investments, the investment advisor will seek to determine the fair value of such investments based on information provided by the general partners or managers of such funds or from other sources. Audited financial statements are provided by fund management annually. Notwithstanding the above, the variety of valuation bases adopted and quality of management data of the ultimate underlying investee companies means that there are inherent difficulties in determining the value of the investments. Amounts realized on the sale of these investments may differ from the calculated values. Boise had originally committed to a $ 15.0 million investment, with $ 5.0 million of the commitment unfunded at December 31, 2019 .
[2]	In accordance with ASC 820, Fair Value Measurement

Employee Benefit Plans and O_12

Employee Benefit Plans and Other Postretirement Benefits - Fair Value Measurements of Plan Assets (Parenthetical) (Details) - Private Equity Securities - Significant unobservable input (Level 3) $ in Millions	Dec. 31, 2019USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment commitment	$ 15
Unfunded portion of investment commitment	$ 5

Employee Benefit Plans and O_13

Employee Benefit Plans and Other Postretirement Benefits - Summary of Changes in Pension Plans' Level 3 Assets (Details) - Pension Plans $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Level 3 fair value of pension plans' assets [Roll Forward]
Plan assets at fair value at beginning of period	$ 873.2
Fair value of plan assets at plan year end	1,073.8
Private Equity Securities
Level 3 fair value of pension plans' assets [Roll Forward]
Plan assets at fair value at beginning of period	3.3	[1]
Fair value of plan assets at plan year end	2.6	[1]
Significant unobservable input (Level 3) | Private Equity Securities
Level 3 fair value of pension plans' assets [Roll Forward]
Plan assets at fair value at beginning of period	3.3	[1]
Sales	(0.7)
Fair value of plan assets at plan year end	$ 2.6	[1]
[1]	Investments in this category are invested in the Pantheon Global Secondary Fund IV, LP. The fund specializes in investments in the private equity secondary market and occasionally directly in private companies to maximize capital growth. Fund investments are carried at fair value as determined quarterly using the market approach to estimate the fair value of private investments. The market approach utilizes prices and other relevant information generated by market transactions, type of security, size of the position, degree of liquidity, restrictions on the disposition, latest round of financing data, current financial position, and operating results, among other factors. In circumstances where fair values are not provided with respect to any of the company's fund investments, the investment advisor will seek to determine the fair value of such investments based on information provided by the general partners or managers of such funds or from other sources. Audited financial statements are provided by fund management annually. Notwithstanding the above, the variety of valuation bases adopted and quality of management data of the ultimate underlying investee companies means that there are inherent difficulties in determining the value of the investments. Amounts realized on the sale of these investments may differ from the calculated values. Boise had originally committed to a $ 15.0 million investment, with $ 5.0 million of the commitment unfunded at December 31, 2019 .

Employee Benefit Plans and O_14

Employee Benefit Plans and Other Postretirement Benefits - Schedule of Estimated Benefit Payments (Details) $ in Millions	Dec. 31, 2019USD ($)
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2020	$ 52.7
2021	56.7
2022	60.4
2023	64.1
2024 - 2029	442.5
Postretirement Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2020	0.7
2021	0.7
2022	0.7
2023	0.7
2024 - 2029	$ 4.5

Asset Retirement Obligations -

Asset Retirement Obligations - Changes to Asset Retirement Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligation at beginning of period	$ 30	$ 35.1
Accretion expense	1.5	1.6
Payments	(3.5)	(7.9)
Revisions in estimated cash flows	(0.2)	1.2
Asset retirement obligation at end of period	$ 27.8	$ 30

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
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 issuance under share-based plan	400,000
Restricted Stock | Officers and Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of ROIC as performance measure	4 years
Vesting period of TSR as performance measure	3 years
Percentage of ROIC as performance measure	50.00%	50.00%
Percentage of TSR as performance measure	50.00%	50.00%

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Restricted Stock and Performance Units Activity (Details) - $ / shares		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock
Restricted Stock and Performance Units [Roll Forward]
Outstanding at January 1		743,591	739,732	786,079
Granted		199,499	173,144	173,199
Vested	[1]	(212,809)	(165,547)	(213,992)
Forfeitures		(13,329)	(3,738)	(5,554)
Outstanding at December 31		716,952	743,591	739,732
Restricted Stock and Performance Units (Weighted Average Grant-date Fair Value) [Abstract]
Weighted Average Grant-Date Fair Value, Outstanding at January 1		$ 86.90	$ 77.23	$ 63.44
Weighted Average Grant-Date Fair Value, Granted		95.48	114.63	107.57
Weighted Average Grant-Date Fair Value, Vested	[1]	68.59	72.84	51.37
Weighted Average Grant-Date Fair Value, Forfeitures		98.86	78.66	69.03
Weighted Average Grant-Date Fair Value, Outstanding at December 31		$ 94.50	$ 86.90	$ 77.23
Performance Units
Restricted Stock and Performance Units [Roll Forward]
Outstanding at January 1		266,704	226,558	232,088
Granted		115,608	83,515	53,070
Vested	[2]	(59,165)	(43,369)	(58,600)
Outstanding at December 31		323,147	266,704	226,558
Restricted Stock and Performance Units (Weighted Average Grant-date Fair Value) [Abstract]
Weighted Average Grant-Date Fair Value, Outstanding at January 1		$ 90.01	$ 77.07	$ 62.68
Weighted Average Grant-Date Fair Value, Granted		96.98	115.35	108.19
Weighted Average Grant-Date Fair Value, Vested	[2]	67.84	71.19	56.08
Weighted Average Grant-Date Fair Value, Outstanding at December 31		$ 96.56	$ 90.01	$ 77.07
[1]	The total fair value of awards upon vesting for the years ended December 31, 2019, 2018, and 2017 was $19.9 million, .
[2]	The total fair value of awards upon vesting for the years ended December 31, 2019, 2018, and 2017 was $5.5 million, $5.4 million, and $7.5 million, respectively. Upon vesting of the awards in 2019, 2018, and 2017, PCA issued 59,165 shares, 46,876 shares, and 67,391 shares, respectively. For 2019, 2018, and 2017, these amounts included 6,063 shares, 3,507 shares, and 8,791 shares, respectively, for dividends accrued during the vesting period.

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Restricted Stock and Performance Units Activity (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	$ 19.9	$ 18.9	$ 23.3
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	$ 5.5	$ 5.4	$ 7.5
Stock Issued During Period, Shares, Restricted Stock Award, Gross	59,165	46,876	67,391
Common Stock Dividends, Shares	6,063	3,507	8,791

Share-Based Compensation - Comp

Share-Based Compensation - Compensation Expense for Share-Based Awards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Impact on income before income taxes	$ 30.4	$ 23.5	$ 20.6
Income tax benefit	(7.6)	(5.9)	(7.9)
Impact on net income	22.8	17.6	12.7
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Impact on income before income taxes	22.6	18.6	15
Performance Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Impact on income before income taxes	$ 7.8	$ 4.9	$ 5.6

Share-Based Compensation - Unre

Share-Based Compensation - Unrecognized Compensation Expense for Share-Based Awards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 44.4
Remaining weighted-average recognition period	2 years 9 months 18 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 27.2
Remaining weighted-average recognition period	3 years 1 month 6 days
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 17.2
Remaining weighted-average recognition period	2 years 4 months 24 days

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2008
Derivative [Line Items]
Amortization of net (loss) gain on treasury lock			$ (18.2)	$ (5.3)	$ (5.7)
3.90% Senior Notes, due June 2022
Derivative [Line Items]
Stated interest rate		3.90%	3.90%
2008 Interest Rate Protection Agreement
Derivative [Line Items]
Payments for (Proceeds from) settlement of interest rate protection agreement								$ 4.4
2010 Interest Rate Protection Agreement
Derivative [Line Items]
Payments for (Proceeds from) settlement of interest rate protection agreement							$ (9.9)
2011 Interest Rate Protection Agreement
Derivative [Line Items]
Payments for (Proceeds from) settlement of interest rate protection agreement						$ 65.5
Treasury Lock
Derivative [Line Items]
Amortization of net (loss) gain on treasury lock	$ (13.1)	$ (13.1)
Amortization of treasury lock settlements, after tax		6.5
Income tax benefit from stranded tax effects in accumulated OCI related to write-off of remaining treasury lock		$ 3.2

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Impact of Derivative Instruments on Consolidated Statements of Income and Accumulated OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest Expense, Net
Derivative Instruments, Gain (Loss) [Line Items]
Loss Reclassified from Accumulated OCI into Income (Effective Portion)	$ (18.2)	$ (5.3)	$ (5.7)
Treasury Locks, Net Of Tax
Derivative Instruments, Gain (Loss) [Line Items]
Net Loss Recognized in Accumulated OCI (Effective Portion)		$ (10.2)

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions	Jan. 15, 2020	Dec. 10, 2019	Jul. 13, 2018	May 15, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 25, 2016
Common stock dividends paid					$ 298,700,000	$ 268,100,000	$ 237,600,000
Dividends paid per common share (in dollars per share)		$ 0.79	$ 0.79
Dividends declared per common share					$ 3.16	$ 3	$ 2.52
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
Annual Dividend [Member]
Dividends declared per common share				$ 3.16			$ 2.52
Subsequent Event
Common stock dividends paid	$ 74,800,000

Stockholders' Equity - Changes

Stockholders' Equity - Changes in Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at December 31, 2018	$ 2,672.4
Other comprehensive income before reclassifications	(40.5)
Amounts reclassified from AOCI	19.8
Other comprehensive income (loss)	(20.7)	$ 18.1	$ (17.3)
Balance at December 31, 2019	3,071	2,672.4
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at December 31, 2018	(0.4)
Balance at December 31, 2019	(0.4)	(0.4)
Unfunded Employee Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at December 31, 2018	(127.9)
Other comprehensive income before reclassifications	(40.5)
Amounts reclassified from AOCI	9.5
Other comprehensive income (loss)	(31)
Balance at December 31, 2019	(158.9)	(127.9)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at December 31, 2018	(138.8)
Balance at December 31, 2019	(159.5)	(138.8)
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 December 31, 2018	(10.2)
Amounts reclassified from AOCI	10.2
Other comprehensive income (loss)	10.2
Balance at December 31, 2019		(10.2)
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 December 31, 2018	(0.3)
Amounts reclassified from AOCI	0.1
Other comprehensive income (loss)	0.1
Balance at December 31, 2019	$ (0.2)	$ (0.3)

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2019

[4]

Sep. 30, 2019

[5]

Jun. 30, 2019

Mar. 31, 2019

[6]

Dec. 31, 2018

[7]

Sep. 30, 2018

[8]

Jun. 30, 2018

[9]

Mar. 31, 2018

[10]

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]

Interest expense, net

$ (128.8)

[1]

$ (95.1)

$ (102.6)

[2],[3]

Income before taxes

917

970.5

828.6

[3]

Income tax benefit

(220.6)

(232.5)

(160)

Net income

$ 136.2

$ 179.8

$ 193.6

$ 186.8

$ 204.6

$ 206.7

$ 186.6

$ 140.1

696.4

738

$ 668.6

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

[11]

(6)

(6.6)

Amortization of actuarial gains / (losses)

[11]

(6.7)

(9.2)

Income before taxes

(12.7)

(15.8)

Income tax benefit

3.2

4

Net income

(9.5)

(11.8)

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

[12]

(18.1)

(5.3)

Income tax benefit

7.9

1.3

Net income

$ (10.2)

$ (4)

[1]

Includes $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs.

[2]

Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing.

[3]

Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

[4]

Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).

[5]

Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).

[6]

Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).

[7]

Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

[8]

Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).

[9]

Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).

[10]

Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).

[11]

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.

[12]

This AOCI component is included in interest expense, net. The remaining balances of the treasury locks were written off  as a result of the Company’s November 2019 debt refinancing. For a discussion of treasury lock derivative instrument activity, see Note 16, Derivative Instruments and Hedging Activities, for additional information.

Concentrations of Risk - Additi

Concentrations of Risk - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)employee	Dec. 31, 2018USD ($)
Concentration Risk [Line Items]
Accounts receivable, net, current	$ 845.6	$ 901.9
Number of employees of PCA | employee	15,500
Percentage of hourly employees represented by unions	63.00%
Workforce Subject to Collective Bargaining Arrangements | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	45.00%
Workforce Subject to Collective Bargaining Arrangements Expiring within One Year | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	9.00%
Office Depot | Credit Concentration Risk
Concentration Risk [Line Items]
Accounts receivable, net, current	$ 76.2	$ 66.7
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	9.00%	7.00%
Paper | Office Depot | Paper Segment Sales Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	50.00%	47.00%

Transactions With Related Par_2

Transactions With Related Parties - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	$ 7,235.8	$ 6,569.7	$ 6,197.5
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	$ 81.7	83.1	86.4
Fiber costs from related parties	81.7	83.1	86.4
Boise Cascade Co-Owner of LTP | Wood Products, Including Chips and Logs
Related Party Transaction [Line Items]
Fiber costs from related parties	$ 16.8	16.8	$ 16.6
Packaging Corporation of America
Related Party Transaction [Line Items]
Variable interest entity, ownership percentage	50.00%
Variable Interest Entity
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	$ 3.9	2.7
Carrying amount of LTP's liabilities	$ 3.9	$ 2.7

Segment Information - Additiona

Segment Information - Additional Information (Details)

3 Months Ended

12 Months Ended

Dec. 31, 2019USD ($)

Sep. 30, 2019USD ($)

[2]

Jun. 30, 2019USD ($)

Mar. 31, 2019USD ($)

[3]

Dec. 31, 2018USD ($)

Sep. 30, 2018USD ($)

[5]

Jun. 30, 2018USD ($)

[6]

Mar. 31, 2018USD ($)

[7]

Dec. 31, 2019USD ($)Segment

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Segment Reporting Information [Line Items]

Number of reportable segments | Segment

3

Net sales

$ 1,720,000,000

[1]

$ 1,750,700,000

$ 1,759,900,000

$ 1,733,700,000

$ 1,746,600,000

[4]

$ 1,809,900,000

$ 1,767,500,000

$ 1,690,600,000

$ 6,964,300,000

$ 7,014,600,000

$ 6,444,900,000

[8]

Foreign operations

Segment Reporting Information [Line Items]

Net sales

394,900,000

487,800,000

$ 390,300,000

Long-Lived Assets

$ 0

$ 0

$ 0

$ 0

[1]

Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).

[2]

Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).

[3]

Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).

[4]

Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

[5]

Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).

[6]

Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).

[7]

Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).

[8]

2017 has not been adjusted under the modified retrospective method for Topic 606.

Segment Information - Segment S

Segment Information - Segment Sales to External Customers by Product Line (Details) - USD ($) $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2019

[1]

Sep. 30, 2019

[2]

Jun. 30, 2019

Mar. 31, 2019

[3]

Dec. 31, 2018

[4]

Sep. 30, 2018

[5]

Jun. 30, 2018

[6]

Mar. 31, 2018

[7]

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Revenue from External Customer [Line Items]

Segment sales to external customers

$ 1,720

$ 1,750.7

$ 1,759.9

$ 1,733.7

$ 1,746.6

$ 1,809.9

$ 1,767.5

$ 1,690.6

$ 6,964.3

$ 7,014.6

$ 6,444.9

[8]

Packaging

Revenue from External Customer [Line Items]

Segment sales to external customers

5,932.2

5,938.5

5,312.3

[8]

Paper

Revenue from External Customer [Line Items]

Segment sales to external customers

964.3

1,002

1,051.8

[8]

Operating Segments

Revenue from External Customer [Line Items]

Segment sales to external customers

6,964.3

7,014.6

6,444.9

Operating Segments | Packaging

Revenue from External Customer [Line Items]

Segment sales to external customers

5,932.2

5,938.5

5,312.3

Operating Segments | Paper

Revenue from External Customer [Line Items]

Segment sales to external customers

964.3

1,002

1,051.8

Operating Segments | Corporate and Other

Revenue from External Customer [Line Items]

Segment sales to external customers

$ 67.8

$ 74.1

$ 80.8

[1]

Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).

[2]

Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).

[3]

Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).

[4]

Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

[5]

Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).

[6]

Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).

[7]

Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).

[8]

2017 has not been adjusted under the modified retrospective method for Topic 606.

Segment Information - Analysis

Segment Information - Analysis of Operations by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended															12 Months Ended
	Dec. 31, 2019		Sep. 30, 2019	[2]	Jun. 30, 2019	Mar. 31, 2019	[3]	Dec. 31, 2018		Sep. 30, 2018	[5]	Jun. 30, 2018	[6]	Mar. 31, 2018	[7]	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ 235.1	[1]	$ 262.8		$ 280.4	$ 275.4		$ 286.7	[4]	$ 298.5		$ 269.6		$ 212.9		$ 1,053.7		$ 1,067.7		$ 932.5	[8]
Net sales	1,720	[1]	$ 1,750.7		$ 1,759.9	$ 1,733.7		1,746.6	[4]	$ 1,809.9		$ 1,767.5		$ 1,690.6		6,964.3		7,014.6		6,444.9	[9]
Non-operating pension expense																(7.9)		(2.1)		(1.3)	[8]
Interest expense, net																(128.8)	[10]	(95.1)		(102.6)	[8],[11]
Income before taxes																917		970.5		828.6	[8]
Depreciation, Amortization, and Depletion																387.5		410.9		391.4
Capital Expenditures																399.5	[8]	551.4	[8]	343
Assets	7,235.8							6,569.7								7,235.8		6,569.7		6,197.5
Trade
Segment Reporting Information [Line Items]
Net sales																6,964.3		7,014.6		6,444.9
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales																(160.2)		(155.6)		(148.4)
Operating Segments
Segment Reporting Information [Line Items]
Net sales																6,964.3		7,014.6		6,444.9
Segment Reconciling Items
Segment Reporting Information [Line Items]
Net sales																(160.2)		(155.6)		(148.4)
Packaging
Segment Reporting Information [Line Items]
Operating Income (Loss)																963.4	[12]	1,045.4	[13]	950.3	[8],[14]
Net sales																5,932.2		5,938.5		5,312.3	[9]
Depreciation, Amortization, and Depletion																342.8		342		317.5
Capital Expenditures																367.4	[8]	504	[8]	305.1
Assets	5,491.5							5,347								5,491.5		5,347		4,933.6
Packaging | Trade
Segment Reporting Information [Line Items]
Net sales																5,905.1		5,912.3		5,288.6
Packaging | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales																27.1		26.2		23.7
Packaging | Operating Segments
Segment Reporting Information [Line Items]
Net sales																5,932.2		5,938.5		5,312.3
Paper
Segment Reporting Information [Line Items]
Operating Income (Loss)																175.4	[15]	97.7	[16]	54	[8],[17]
Net sales																964.3		1,002		1,051.8	[9]
Depreciation, Amortization, and Depletion																37.7		62		67.6
Capital Expenditures																23.8	[8]	12.6	[8]	22.6
Assets	791.4							760.1								791.4		760.1		945.2
Paper | Trade
Segment Reporting Information [Line Items]
Net sales																964.3		1,002		1,051.8
Paper | Operating Segments
Segment Reporting Information [Line Items]
Net sales																964.3		1,002		1,051.8
Corporate and Other
Segment Reporting Information [Line Items]
Operating Income (Loss)																(85.1)		(75.4)	[18]	(71.8)	[8],[19]
Net sales																67.8		74.1		80.8	[9]
Depreciation, Amortization, and Depletion																7		6.9		6.3
Capital Expenditures																8.3	[8]	34.8	[8]	15.3
Assets	$ 952.9							$ 462.6								952.9		462.6		318.7
Corporate and Other | Trade
Segment Reporting Information [Line Items]
Net sales																94.9		100.3		104.5
Corporate and Other | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales																133.1		129.4		124.7
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Net sales																$ 228		$ 229.7		$ 229.2
[1]	Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).
[2]	Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).
[3]	Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).
[4]	Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act
[5]	Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).
[6]	Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).
[7]	Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).
[8]	Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.
[9]	2017 has not been adjusted under the modified retrospective method for Topic 606.
[10]	Includes $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs.
[11]	Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing.
[12]	(b) Includes the following: o $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill. o $0.8 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility
[13]	(e) Includes the following: o $12.3 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $1.6 million of charges consisting of closure costs related to corrugated products facilities. o $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. o $0.2 million of charges for acquisition and integration costs related to recent acquisitions.
[14]	(h) o $7.2 million of income, net, primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. o $1.7 million of charges for acquisition and integration costs related to recent acquisitions. o $2.0 million gain related to the expiration of a repurchase option corresponding to timberland previously sold. o $1.6 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico. o $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.
[15]	Includes $0.2 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard.
[16]	Includes $17.7 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard.
[17]	Includes $33.4 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard and $0.4 million of charges related to the closure costs of a paper administration facility.
[18]	Includes $0.2 million of charges consisting of closure costs related to a corporate administration facility.
[19]	Includes $1.0 million of charges related to the closure costs of a corporate administration facility and $0.7 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 - Analysi_2

Segment Information - Analysis of Operations by Reportable Segment (Parenthetical) (Details) - USD ($) $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

[2]

Jun. 30, 2019

Mar. 31, 2019

[3]

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Segment Reporting Information [Line Items]

Operating Income (Loss)

$ 235.1

[1]

$ 262.8

$ 280.4

$ 275.4

$ 286.7

[4]

$ 298.5

[5]

$ 269.6

[6]

$ 212.9

[7]

$ 1,053.7

$ 1,067.7

$ 932.5

[8]

Non-operating pension expense

(7.9)

(2.1)

(1.3)

[8]

Interest expense, net

(128.8)

[9]

(95.1)

(102.6)

[8],[10]

Income before taxes

917

970.5

828.6

[8]

Acquisition and integration related costs

[11]

0.2

0.8

Hexacomb working capital adjustment

[12]

2.3

Write-Off of Deferred Financing Costs

Segment Reporting Information [Line Items]

Interest expense, net

(1.8)

Corrugated Products Facility Closure

Segment Reporting Information [Line Items]

Restructuring charges

0.3

0.5

Debt Refinancing

Segment Reporting Information [Line Items]

Restructuring charges

$ 38.7

38.7

DeRidder, Louisiana Mill

Segment Reporting Information [Line Items]

Charges for disposal of fixed assets

3

Wallula, Washington Mill

Segment Reporting Information [Line Items]

Restructuring charges

3.6

$ 4

$ 13.6

$ 8.8

ASU 2017-07 | As Reported

Segment Reporting Information [Line Items]

Operating Income (Loss)

931.2

Interest expense, net

(102.6)

Income before taxes

828.6

ASU 2017-07 | Non-Operating Pension Adjustment

Segment Reporting Information [Line Items]

Operating Income (Loss)

1.3

Non-operating pension expense

(1.3)

Packaging

Segment Reporting Information [Line Items]

Operating Income (Loss)

963.4

[13]

1,045.4

[14]

950.3

[8],[15]

Restructuring charges

0.3

1.6

Property damage and business interruption insurance

$ 0.5

0.5

Acquisition and integration related costs

0.2

1.7

Packaging | Hexacomb Europe and Mexico

Segment Reporting Information [Line Items]

Acquisition and integration related costs

1.6

Packaging | Corrugated Products Facility Closure

Segment Reporting Information [Line Items]

Operating Income (Loss)

7.2

Packaging | Timberland

Segment Reporting Information [Line Items]

Operating Income (Loss)

2

Packaging | DeRidder, Louisiana Mill

Segment Reporting Information [Line Items]

Charges for disposal of fixed assets

3

Property damage and business interruption insurance

5

Packaging | Wallula, Washington Mill

Segment Reporting Information [Line Items]

Restructuring charges

0.8

12.3

Packaging | ASU 2017-07 | As Reported

Segment Reporting Information [Line Items]

Operating Income (Loss)

943.7

Packaging | ASU 2017-07 | Non-Operating Pension Adjustment

Segment Reporting Information [Line Items]

Operating Income (Loss)

6.6

Paper

Segment Reporting Information [Line Items]

Operating Income (Loss)

175.4

[16]

97.7

[17]

54

[8],[18]

Facilities closure costs

0.4

Paper | Wallula, Washington Mill

Segment Reporting Information [Line Items]

Restructuring charges

0.2

17.7

33.4

Paper | ASU 2017-07 | As Reported

Segment Reporting Information [Line Items]

Operating Income (Loss)

61.5

Paper | ASU 2017-07 | Non-Operating Pension Adjustment

Segment Reporting Information [Line Items]

Operating Income (Loss)

(7.5)

Corporate and Other

Segment Reporting Information [Line Items]

Operating Income (Loss)

$ (85.1)

(75.4)

[19]

(71.8)

[8],[20]

Restructuring charges

$ 0.2

Facilities closure costs

1

Corporate and Other | Hexacomb Europe and Mexico

Segment Reporting Information [Line Items]

Hexacomb working capital adjustment

0.7

Corporate and Other | ASU 2017-07 | As Reported

Segment Reporting Information [Line Items]

Operating Income (Loss)

(74)

Corporate and Other | ASU 2017-07 | Non-Operating Pension Adjustment

Segment Reporting Information [Line Items]

Operating Income (Loss)

$ 2.2

[1]

Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).

[2]

Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).

[3]

Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).

[4]

Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act

[5]

Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).

[6]

Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).

[7]

Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).

[8]

Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

[9]

Includes $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs.

[10]

Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing.

[11]

Includes charges for acquisition and integration costs related to recent acquisitions.

[12]

Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

[13]

(b) Includes the following: o $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill. o $0.8 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility

[14]

(e) Includes the following: o $12.3 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard. o $1.6 million of charges consisting of closure costs related to corrugated products facilities. o $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities. o $0.2 million of charges for acquisition and integration costs related to recent acquisitions.

[15]

(h) o $7.2 million of income, net, primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities. o $1.7 million of charges for acquisition and integration costs related to recent acquisitions. o $2.0 million gain related to the expiration of a repurchase option corresponding to timberland previously sold. o $1.6 million of income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico. o $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.

[16]

Includes $0.2 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard.

[17]

Includes $17.7 million of charges related to the second quarter discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard.

[18]

Includes $33.4 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard and $0.4 million of charges related to the closure costs of a paper administration facility.

[19]

Includes $0.2 million of charges consisting of closure costs related to a corporate administration facility.

[20]

Includes $1.0 million of charges related to the closure costs of a corporate administration facility and $0.7 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_3

Commitments, Guarantees, Indemnifications, and Legal Proceedings - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 08, 2017
Schedule Of Commitments And Contingencies [Line Items]
Capital commitments			$ 212,600,000	$ 112,800,000
Purchases during period under purchase agreements			315,000,000	341,900,000	$ 339,100,000
Environmental reserve			24,600,000
Environmental liabilities and asset retirement obligations			$ 5,600,000	$ 5,000,000
DeRidder, Louisiana
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
Asset Retirement Obligation
Schedule Of Commitments And Contingencies [Line Items]
Environmental reserve			$ 15,700,000
Environmental Contingencies
Schedule Of Commitments And Contingencies [Line Items]
Environmental reserve			8,900,000
Other Long-Term Liabilities
Schedule Of Commitments And Contingencies [Line Items]
Environmental reserve			$ 19,000,000
Minimum
Schedule Of Commitments And Contingencies [Line Items]
Purchase commitments term, years			1 year
Maximum
Schedule Of Commitments And Contingencies [Line Items]
Purchase commitments term, years			31 years

Commitments, Guarantees, Inde_4

Commitments, Guarantees, Indemnifications, and Legal Proceedings - Schedule of Purchase Commitments (Details) $ in Millions	Dec. 31, 2019USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020	$ 51.9
2021	47.4
2022	43
2023	42.8
2024	24.6
Thereafter	109.3
Total	$ 319

Quarterly Results of Operatio_3

Quarterly Results of Operations (Unaudited) - Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended															12 Months Ended
	Dec. 31, 2019	[1]	Sep. 30, 2019	[2]	Jun. 30, 2019	Mar. 31, 2019	[3]	Dec. 31, 2018	[4]	Sep. 30, 2018	[5]	Jun. 30, 2018	[6]	Mar. 31, 2018	[7]	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,720		$ 1,750.7		$ 1,759.9	$ 1,733.7		$ 1,746.6		$ 1,809.9		$ 1,767.5		$ 1,690.6		$ 6,964.3	$ 7,014.6	$ 6,444.9	[8]
Gross profit	383.3		411.4		427.9	421.4		425.4		443.2		420.6		356.1		1,644	1,645.3	1,470.8
Operating Income (Loss)	235.1		262.8		280.4	275.4		286.7		298.5		269.6		212.9		1,053.7	1,067.7	932.5	[9]
Net income	$ 136.2		$ 179.8		$ 193.6	$ 186.8		$ 204.6		$ 206.7		$ 186.6		$ 140.1		$ 696.4	$ 738	$ 668.6
Basic	$ 1.44		$ 1.90		$ 2.05	$ 1.98		$ 2.17		$ 2.19		$ 1.98		$ 1.48		$ 7.36	$ 7.82	$ 7.09
Diluted	1.43		1.89		2.04	1.97		2.16		2.18		1.97		1.48		7.34	7.80	$ 7.07
Stock price - high	114.78		109.37		103.80	101.84		110.62		118.88		124.70		131.13		114.78	131.13
Stock price - low	$ 100.54		$ 96.30		$ 87.85	$ 81.87		$ 77.90		$ 107.39		$ 107.96		$ 109.04		$ 81.87	$ 77.90
[1]	Includes $0.4 million of charges consisting of closure costs related related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.3 million after-tax or $0.00 per diluted share) and $38.7 million of charges related to the Company’s November 2019 debt refinancing, which included redemption premiums and the write-offs of remaining balances of treasury locks and unamortized debt issuance costs as well as $ 3.2 million of income tax benefit from the stranded tax effects in Accumulated Other Comprehensive Income related to the write-offs of the treasury locks ($ 25.9 million after-tax or $ 0.28 per diluted share). Also includes $ 0.3 million of charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility ($ 0.2 million after-tax or $ per diluted share).
[2]	Includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill ($2.3 million after-tax or $0.02 per diluted share).
[3]	Includes $0.6 million of charges consisting of closure costs related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($0.5 million after-tax or $0.01 per diluted share).
[4]	Includes $3.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.7 million after-tax or $0.03 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.1 million after-tax or $0.00 per diluted share). Also includes $2.0 million of income tax benefit for the re-measurement of our net deferred tax liability to our 2017 measurement period adjustments in accordance with SEC Staff Accounting Bulletin No. 118 (SAB 118), Income Tax Accounting Implications of the Tax Cuts and Jobs Act
[5]	Includes $4.0 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($2.9 million after-tax or $0.04 per diluted share) and $1.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($1.0 million after-tax or $0.01 per diluted share). Also includes $0.5 million of costs for the property damage insurance deductible for a weather-related incident at one of the corrugated products facilities ($0.4 million after-tax or $0.00 per diluted share) and $0.1 million of charges for acquisition and integration costs related to recent acquisitions ($0.01 million after-tax or $0.00 per diluted share).
[6]	Includes $0.2 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax and $0.00 per diluted share) and $13.6 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($10.2 million after-tax or $0.11 per diluted share).
[7]	Includes $0.3 million of charges consisting of closure costs related to corrugated products facilities and a corporate administration facility ($0.2 million after-tax or $0.00 per diluted share) and $8.8 million of charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side white paper grades at the Wallula Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard ($6.6 million after-tax or $0.07 per diluted share).
[8]	2017 has not been adjusted under the modified retrospective method for Topic 606.
[9]	Includes “Additions to property, plant, and equipment” and excludes cash used for “Acquisitions of businesses, net of cash acquired” as reported on our Consolidated Statements of Cash Flows.

Quarterly Results of Operatio_4

Quarterly Results of Operations (Unaudited) - Summary of Quarterly Financial Data (Parenthetical) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019
U.S. federal
Quarterly Financial Data [Line Items]
Restructuring charges, diluted per share				$ 0.02
Income tax benefit related to enactment of Tax Cuts and Jobs Act				$ 2,000
Integration Costs Related to Recent Acquisitions
Quarterly Financial Data [Line Items]
Restructuring charges				100	$ 100
Restructuring charges, after tax				$ 100	$ 10
Restructuring charges, diluted per share				$ 0	$ 0
Corrugated Products Facility Closure
Quarterly Financial Data [Line Items]
Restructuring charges	$ 300				$ 500
Restructuring charges, after tax	$ 200				$ 400
Restructuring charges, diluted per share	$ 0				$ 0
Debt Refinancing
Quarterly Financial Data [Line Items]
Restructuring charges	$ 38,700							$ 38,700
Treasury Lock
Quarterly Financial Data [Line Items]
Restructuring charges, after tax	$ 25,900
Restructuring charges, diluted per share	$ 0.28
Income tax benefit from stranded tax effects in accumulated OCI related to write-off of remaining treasury lock	$ 3,200
Packaging And Corporate And Other
Quarterly Financial Data [Line Items]
Restructuring charges	400	$ 3,000	$ 600		$ 1,300	$ 200	$ 300
Restructuring charges, after tax					$ 1,000	$ 200	$ 200
Restructuring charges, diluted per share					$ 0.01	$ 0	$ 0
Wallula, Washington Mill
Quarterly Financial Data [Line Items]
Restructuring charges				$ 3,600	$ 4,000	$ 13,600	$ 8,800
Restructuring charges, after tax	$ 300	$ 2,300	$ 500	$ 2,700	$ 2,900	$ 10,200	$ 6,600
Restructuring charges, diluted per share	$ 0	$ 0.02	$ 0.01	$ 0.03	$ 0.04	$ 0.11	$ 0.07