WestRock (WRK) 10-Q 7 May 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Mar. 31, 2021	Apr. 23, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Trading Symbol	WRK
Entity Registrant Name	WestRock Company
Entity Central Index Key	0001732845
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		266,116,343
Entity Current Reporting Status	Yes
Title of 12(b) Security	Common Stock, par value $0.01 per share
Entity File Number	001-38736
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	37-1880617
Entity Interactive Data Current	Yes
Security Exchange Name	NYSE
Entity Address, Address Line One	1000 Abernathy Road NE
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30328
City Area Code	770
Local Phone Number	448-2193
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 4,437.8	$ 4,447.3	$ 8,839.3	$ 8,871
Cost of goods sold	3,688.2	3,642.5	7,336.8	7,257.2
Gross profit	749.6	804.8	1,502.5	1,613.8
Selling, general and administrative, excluding intangible amortization	458.4	418.6	876.2	844.3
Selling, general and administrative intangible amortization	88.6	100.1	180.5	201.9
Loss (gain) on disposal of assets	0.3	(5.6)	2.8	(6.9)
Multiemployer pension withdrawal expense		0.9		0.9
Restructuring and other costs	5.2	16.4	12.9	46.5
Operating profit	197.1	274.4	430.1	527.1
Interest expense, net	(83.5)	(97.3)	(177.3)	(190.8)
Loss on extinguishment of debt		(0.5)	(1.1)	(0.5)
Pension and other postretirement non-service income	35	26.1	69.9	52.8
Other (expense) income, net	(13.4)	(0.9)	7.4	(4.6)
Equity in income of unconsolidated entities	9.7	4.9	18.7	8.7
Income before income taxes	144.9	206.7	347.7	392.7
Income tax expense	(30.5)	(57.8)	(80.8)	(104.3)
Consolidated net income	114.4	148.9	266.9	288.4
Less: Net income attributable to noncontrolling interests	(1.9)	(0.8)	(2.4)	(1.8)
Net income attributable to common stockholders	$ 112.5	$ 148.1	$ 264.5	$ 286.6
Basic earnings per share attributable to common stockholders	$ 0.42	$ 0.57	$ 1	$ 1.11
Diluted earnings per share attributable to common stockholders	$ 0.42	$ 0.57	$ 0.99	$ 1.10
Basic weighted average shares outstanding	264.9	259	263.8	258.6
Diluted weighted average shares outstanding	267	260.2	265.9	260.1

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income	$ 114.4	$ 148.9	$ 266.9	$ 288.4
Other comprehensive income, net of tax:
Foreign currency translation (loss) gain	(87.2)	(387.5)	109.7	(287.1)
Derivatives:
Deferred loss on cash flow hedges		(8.9)	(0.1)	(9.4)
Reclassification adjustment of net loss on cash flow hedges included in earnings	1.4	2.5	2.9	1.2
Defined benefit pension and other postretirement benefit plans:
Amortization and settlement recognition of net actuarial loss, included in pension cost	5.8	8.5	11.4	17.2
Amortization and settlement recognition of prior service cost, included in pension cost	1	1	2.1	1.5
Other comprehensive (loss) income, net of tax	(79)	(384.4)	126	(276.6)
Comprehensive income (loss)	35.4	(235.5)	392.9	11.8
Less: Comprehensive income attributable to noncontrolling interests	(1.9)	(0.5)	(2.8)	(1.6)
Comprehensive income (loss) attributable to common stockholders	$ 33.5	$ (236)	$ 390.1	$ 10.2

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions		Mar. 31, 2021	Sep. 30, 2020
Current assets:
Cash and cash equivalents		$ 334	$ 251.1
Accounts receivable (net of allowances of $71.5 and $66.3)		2,416.2	2,142.7
Inventories		2,090.9	2,023.4
Other current assets		529.8	520.5
Assets held for sale		13.7	7
Total current assets		5,384.6	4,944.7
Property, plant and equipment, net		10,572.5	10,778.9
Goodwill		5,959.1	5,962.2
Intangibles, net		3,499.9	3,667.2
Restricted assets held by special purpose entities		1,264	1,267.5
Prepaid pension asset		436.8	368.7
Other assets		1,855	1,790.5
Total Assets		28,971.9	28,779.7
Current liabilities:
Current portion of debt		549.5	222.9
Accounts payable		1,796.8	1,674.2
Accrued compensation and benefits		515.1	386.7
Other current liabilities		691.3	645.1
Total current liabilities		3,552.7	2,928.9
Long-term debt due after one year		8,393.1	9,207.7
Pension liabilities, net of current portion		298.5	305.2
Postretirement benefit liabilities, net of current portion		147	145.4
Non-recourse liabilities held by special purpose entities		1,132	1,136.5
Deferred income taxes		2,872.6	2,916.9
Other long-term liabilities		1,503.8	1,490.3
Commitments and contingencies (Note 13)
Redeemable noncontrolling interests		2.2	1.3
Equity:
Preferred stock, $0.01 par value; 30.0 million shares authorized; no shares outstanding		0	0
Common Stock, $0.01 par value; 600.0 million shares authorized; 265.9 million and 260.4 million shares outstanding at March 31, 2021 and September 30, 2020, respectively		2.7	2.6
Capital in excess of par value		11,057.5	10,916.3
Retained earnings		1,186	1,031.6
Accumulated other comprehensive loss	[1]	(1,194.3)	(1,319.9)
Total stockholders’ equity		11,051.9	10,630.6
Noncontrolling interests		18.1	16.9
Total equity		11,070	10,647.5
Total Liabilities and Equity		$ 28,971.9	$ 28,779.7
[1]	All amounts are net of tax and noncontrolling interests.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Statement Of Financial Position [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 71.5	$ 66.3
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	30,000,000	30,000,000
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	600,000,000	600,000,000
Common Stock, Shares, Outstanding	265,900,000	260,400,000

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Millions, $ in Millions		Total		Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Retained Earnings [Member]Adoption of Accounting Standards [Member]	AOCI Attributable to Parent	AOCI Attributable to ParentAdoption of Accounting Standards [Member]	Noncontrolling Interests [Member]	[1]
Beginning balance at Sep. 30, 2019				257.8
Beginning balance at Sep. 30, 2019				$ 2.6	$ 10,739.4	$ 1,997.1		$ (1,069.2)		$ 14.3
Adoption of accounting standards	[2]						$ 73.5		$ (73.4)
Issuance of common stock, net of stock received for tax withholdings				1.4
Issuance of common stock, net of stock received for tax withholdings					15.5
Compensation expense under share-based plans					29.5
Net income attributable to common stockholders						286.6
Dividends declared (per share - $0.20, $0.465, $0.40 and $0.93	[3]					(242.8)
Other comprehensive (loss) income, net of tax		$ (276.4)	[4]					(276.4)
Net income		(1.8)								1.3
Total Stockholders’ equity at Mar. 31, 2020		11,482.4
Ending balance at Mar. 31, 2020				259.2
Ending balance at Mar. 31, 2020		11,498		$ 2.6	10,784.4	2,114.4		(1,419)		15.6
Beginning balance at Dec. 31, 2019				258.4
Beginning balance at Dec. 31, 2019				$ 2.6	10,770	2,087.5		(1,034.9)		15.3
Issuance of common stock, net of stock received for tax withholdings				0.8
Issuance of common stock, net of stock received for tax withholdings					(1.6)
Compensation expense under share-based plans					16
Net income attributable to common stockholders						148.1
Dividends declared (per share - $0.20, $0.465, $0.40 and $0.93	[3]					(121.2)
Other comprehensive (loss) income, net of tax								(384.1)
Net income		(0.8)								0.3
Total Stockholders’ equity at Mar. 31, 2020		11,482.4
Ending balance at Mar. 31, 2020				259.2
Ending balance at Mar. 31, 2020		$ 11,498		$ 2.6	10,784.4	2,114.4		(1,419)		15.6
Beginning balance at Sep. 30, 2020		260.4		260.4
Total Stockholders' equity at Sep. 30, 2020		$ 10,630.6
Beginning balance at Sep. 30, 2020		10,647.5		$ 2.6	10,916.3	1,031.6		(1,319.9)		16.9
Adoption of accounting standards	[2]						$ (3.8)
Issuance of common stock, net of stock received for tax withholdings				5.5
Issuance of common stock, net of stock received for tax withholdings				$ 0.1	90.3	(0.2)
Compensation expense under share-based plans					50.9
Net income attributable to common stockholders						264.5
Dividends declared (per share - $0.20, $0.465, $0.40 and $0.93	[3]					(106.1)
Other comprehensive (loss) income, net of tax		125.6	[4]					125.6
Net income		(2.4)								1.2
Total Stockholders’ equity at Mar. 31, 2021		$ 11,051.9
Ending balance at Mar. 31, 2021		265.9		265.9
Ending balance at Mar. 31, 2021		$ 11,070		$ 2.7	11,057.5	1,186		(1,194.3)		18.1
Beginning balance at Dec. 31, 2020				263.3
Beginning balance at Dec. 31, 2020				$ 2.6	10,949.4	1,126.3		(1,115.3)		17.1
Issuance of common stock, net of stock received for tax withholdings				2.6
Issuance of common stock, net of stock received for tax withholdings				$ 0.1	77.1	(0.2)
Compensation expense under share-based plans					31
Net income attributable to common stockholders						112.5
Dividends declared (per share - $0.20, $0.465, $0.40 and $0.93	[3]					(52.6)
Other comprehensive (loss) income, net of tax								(79)
Net income		(1.9)								1
Total Stockholders’ equity at Mar. 31, 2021		$ 11,051.9
Ending balance at Mar. 31, 2021		265.9		265.9
Ending balance at Mar. 31, 2021		$ 11,070		$ 2.7	$ 11,057.5	$ 1,186		$ (1,194.3)		$ 18.1
[1]	Excludes amounts related to contingently redeemable noncontrolling interests, which are separately classified outside of permanent equity on the Condensed Consolidated Balance Sheets.
[2]	For fiscal 2021, the amount relates to the adoption of ASU 2016-13 (as hereinafter defined). For fiscal 2020, the amount relates primarily to the adoption of ASU 2018-02, “ Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income ” .
[3]	Includes cash dividends paid and dividend equivalent units on certain restricted stock awards.
[4]	All amounts are net of tax and noncontrolling interests.

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement Of Stockholders Equity [Abstract]
Cash dividends paid per share	$ 0.20	$ 0.465	$ 0.40	$ 0.93

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Consolidated net income	$ 266.9	$ 288.4
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Depreciation, depletion and amortization	725.9	755.7
Cost of real estate sold		16.1
Deferred income tax (benefit) expense	(54.6)	11.4
Share-based compensation expense	51.1	29.6
401(k) match and company contribution in common stock	89.5
Pension and other postretirement funding more than expense (income)	(56.1)	(41.1)
Gain on sale of sawmill	(16.5)
Gain on sale of investment	(14.7)
Multiemployer pension withdrawal expense		0.9
Other impairment adjustments	22.5	2.2
Loss (gain) on disposal of plant and equipment and other, net	2.8	(6.2)
Other, net	(53.1)	(11.3)
Change in operating assets and liabilities, net of acquisitions and divestitures:
Accounts receivable	(257)	(60.4)
Inventories	(79.9)	(63.2)
Other assets	(126.6)	(132.9)
Accounts payable	111.5	(106.7)
Income taxes	52.7	17.7
Accrued liabilities and other	187.2	(101.4)
Net cash provided by operating activities	851.6	598.8
Investing activities:
Capital expenditures	(303)	(616.2)
Investment in unconsolidated entities	(0.1)	(0.7)
Proceeds from sale of sawmill	58.5
Proceeds from sale of investments	28.3
Proceeds from sale of property, plant and equipment	3.1	21.3
Proceeds from property, plant and equipment insurance settlement	1.7	1.4
Other, net	16.3	4.9
Net cash used for investing activities	(195.2)	(589.3)
Financing activities:
Additions to revolving credit facilities	395	375
Repayments of revolving credit facilities	(275)	(65)
Additions to debt	255.2	580.1
Repayments of debt	(857)	(208.2)
Repayments of commercial paper, net		(34.8)
Other debt additions, net	7	85.9
Issuances of common stock, net of related tax withholdings	0.2	13.4
Cash dividends paid to stockholders	(105.8)	(240.7)
Cash distributions paid to noncontrolling interests	(0.7)	(0.7)
Other, net	(3.5)	2.1
Net cash (used for) provided by financing activities	(584.6)	507.1
Effect of exchange rate changes on cash, cash equivalents and restricted cash	11.1	(28)
Increase in cash, cash equivalents and restricted cash	82.9	488.6
Cash, cash equivalents and restricted cash at beginning of period	251.1	151.6
Cash, cash equivalents and restricted cash at end of period	334	640.2
Supplemental disclosure of cash flow information:
Income taxes, net of refunds	82.2	75.1
Interest, net of amounts capitalized	$ 174.7	$ 204.4

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	6 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Note 1. Basis of Presentation and Significant Accounting Policies Basis of Presentation Our independent registered public accounting firm has not audited the accompanying interim financial statements. We derived the condensed consolidated balance sheet at September 30, 2020 from the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2020 (the “ Fiscal 2020 Form 10-K We have condensed or omitted certain notes and other information from the interim financial statements presented in this report. Therefore, these interim financial statements should be read in conjunction with the Fiscal 2020 Form 10-K. The results for the three and six months ended March 31, 2021 are not necessarily indicative of results that may be expected for the full year. Reclassifications and Adjustments Certain amounts in prior periods have been reclassified to conform with the current year presentation. COVID-19 Pandemic The global impact of the COVID-19 pandemic (“ COVID-19 At March 31, 2021, we evaluated the then current economic environment, including our assessment of the impact of COVID-19, as well as the ransomware incident discussed below, and there were no indicators of impairment of our long-lived assets, including goodwill, that required a quantitative test to be performed. Our estimates involve numerous assumptions about the future growth and potential volatility in revenues and costs, capital expenditures, industry and global economic factors, interest rate environment and future business strategy. Accordingly, our accounting estimates may materially change from period to period due to changing market factors, including those driven by COVID-19. We will continue to monitor future events, changes in circumstances and the potential impact thereof, including performing interim goodwill impairment assessments, as warranted. If actual results are not consistent with our assumptions and estimates, we may be exposed to impairment losses that could be material. See “ Note 1. Description of Business and Summary of Significant Accounting Policies — Goodwill and Long-Lived Assets ” in the Fiscal 2020 Form 10-K for additional information regarding the results of, and our methods and assumptions applied to perform, our goodwill impairment testing in fiscal 2020. Ransomware Incident As previously disclosed, on January 23, 2021 we detected a ransomware incident impacting certain of our systems. Promptly upon our detection of this incident, we initiated response and containment protocols and our security teams, supplemented by leading cyber defense firms, worked to remediate this incident. These actions included taking preventative measures, including shutting down certain systems out of an abundance of caution, as well as taking steps to supplement existing security monitoring, scanning and protective measures. We notified law enforcement and contacted our customers to apprise them of the situation. We undertook extensive efforts to identify, contain and recover from this incident quickly and securely. Our teams worked to maintain our business operations and minimize the impact on our customers and teammates. All systems are back in service. All of our mills and converting locations began producing and shipping paper and packaging at pre-ransomware levels in March 2021 or earlier. Our mill system production was approximately 115,000 tons lower than planned for the quarter ended March 31, 2021 as a result of this incident. While shipments from some of our facilities initially lagged behind production levels, this gap closed as systems were restored during the second quarter of fiscal 2021. In locations where technology issues were identified, we used alternative methods, in many cases manual methods, to process and ship orders. We systematically brought our information systems back online in a controlled, phased approach. We estimate the segment income impact of the lost sales and operational disruption of this incident on our operations in the second quarter of fiscal 2021 to be approximately $50 million, as well as approximately $20 million of ransomware recovery costs, primarily professional fees. We estimate that the total insurance claim will be approximately $75 million. We expect to recover substantially all of the ransomware losses from cyber and business interruption insurance in future periods. Disputes over the extent of insurance coverage for claims are not uncommon, and there will be a time lag between the initial incurrence of costs and the receipt of any insurance proceeds. While the impact of lost sales and operational disruption is behind us, we expect to incur some additional recovery costs in the second half of fiscal 2021, albeit at a diminished rate. We are making information technology investments that we had planned to make in future periods in order to further strengthen our information security infrastructure. We engaged a leading cybersecurity defense firm that completed a forensics investigation of the ransomware incident and we are taking appropriate actions in response to the findings. For example, in the short-term, we reset all credentials Company-wide and strengthened security tooling across our servers and workstations. In the long-term, we are continuing to advance the maturity and effectiveness of our information security resiliency strategy and capabilities. Our technology team has accelerated its roadmap to further strengthen the resiliency of our information security infrastructure across the Company that aims to enable us to detect, respond and recover more quickly from security and technical incidents. More specifically, we plan to take actions to improve our security monitoring capabilities and enhance the information security within our mills and plants. Significant Accounting Policies See “ Note 1. Description of Business and Summary of Significant Accounting Policies Recent Accounting Developments New Accounting Standards — Recently Adopted In November 2018, the Financial Accounting Standards Board (“ FASB ASU Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 ASC Collaborative arrangements ASC Revenues from Contracts with Customers ASC 606 In October 2018, the FASB issued ASU 2018-17 “ Consolidation: Targeted Improvements to Related Party Guidance for Variable Interest Entities ”. This ASU changes how entities evaluate decision-making fees under the variable interest entity guidance. To determine whether decision-making fees represent a variable interest, an entity considers indirect interests held through related parties under common control on a proportionate basis, rather than in their entirety, as currently required under generally accepted accounting principles in the U.S. (“ GAAP ”). We adopted the provisions of ASU 2018-17 on October 1, 2020. The adoption did not have a material impact on our consolidated financial statements. In August 2018, the FASB issued 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 In August 2018, the FASB issued ASU 2018-14 “ Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans In June 2016, the FASB issued ASU 2016-13 “ Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) ASU 2016-13 and replaces the incurred loss model with a model that reflects expected credit losses Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments ASU 2019-04 “Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief” ASU 2019-05 Codification Improvements to Topic 326, Financial Instruments – Credit Losses ASU 2019-11 Financial Instruments – Credit Losses (Topic 326) and Leases (Topic 842) ASU 2020-02 modified retrospective transition approach of resulted in us recognizing New Accounting Standards — Recently Issued In March 2020, the FASB issued ASU 2020-04 “ Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” LIBOR In December 2019, the FASB issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”

Revenue Recognition

Revenue Recognition	6 Months Ended
	Mar. 31, 2021
Revenue From Contract With Customer [Abstract]
Revenue Recognition	Note 2. Revenue Recognition Disaggregated Revenue ASC 606 are attributed to geographical markets based on our selling location. In fiscal 2020, we completed our real estate monetization; therefore, we will not have any Land and Development sales in fiscal 2021 Three Months Ended March 31, 2021 (In millions) Corrugated Packaging Consumer Packaging Intersegment Sales Total Primary Geographical Markets North America $ 2,797.1 $ 1,231.7 $ (65.3 ) $ 3,963.5 South America 96.5 23.1 — 119.6 Europe 1.1 265.9 — 267.0 Asia Pacific 18.7 69.2 (0.2 ) 87.7 Total $ 2,913.4 $ 1,589.9 $ (65.5 ) $ 4,437.8 Six Months Ended March 31, 2021 (In millions) Corrugated Packaging Consumer Packaging Intersegment Sales Total Primary Geographical Markets North America $ 5,567.3 $ 2,485.7 $ (123.2 ) $ 7,929.8 South America 177.5 45.3 — 222.8 Europe 2.0 515.2 (0.1 ) 517.1 Asia Pacific 31.1 138.8 (0.3 ) 169.6 Total $ 5,777.9 $ 3,185.0 $ (123.6 ) $ 8,839.3 Three Months Ended March 31, 2020 (In millions) Corrugated Packaging Consumer Packaging Land and Development Intersegment Sales Total Primary Geographical Markets North America $ 2,765.7 $ 1,281.6 $ — $ (51.4 ) $ 3,995.9 South America 100.7 18.8 — — 119.5 Europe 2.5 253.4 — — 255.9 Asia Pacific 13.6 62.5 — (0.1 ) 76.0 Total $ 2,882.5 $ 1,616.3 $ — $ (51.5 ) $ 4,447.3 Six Months Ended March 31, 2020 (In millions) Corrugated Packaging Consumer Packaging Land and Development Intersegment Sales Total Primary Geographical Markets North America $ 5,554.6 $ 2,480.4 $ 18.9 $ (92.9 ) $ 7,961.0 South America 208.3 38.8 — — 247.1 Europe 4.3 498.0 — — 502.3 Asia Pacific 24.8 136.0 — (0.2 ) 160.6 Total $ 5,792.0 $ 3,153.2 $ 18.9 $ (93.1 ) $ 8,871.0 Revenue Contract Balances Contract assets are rights to consideration in exchange for goods that we have transferred to a customer when that right is conditional on something other than the passage of time. Contract assets are reduced when the control of the goods passes to the customer. Contract liabilities represent obligations to transfer goods or services to a customer for which we have received consideration. Contract liabilities are reduced once control of the goods is transferred to the customer. The opening and closing balances of our contract assets and contract liabilities are as follows. Contract assets and contract liabilities are reported within Other current assets and Other current liabilities, respectively, on the condensed consolidated balance sheet. (In millions) Contract Assets (Short-Term) Contract Liabilities (Short-Term) Beginning balance - October 1, 2020 $ 185.8 $ 12.0 Ending balance - March 31, 2021 191.1 21.9 Increase $ 5.3 $ 9.9

Restructuring and Other Costs

Restructuring and Other Costs	6 Months Ended
	Mar. 31, 2021
Restructuring And Other Costs [Abstract]
Restructuring and Other Costs	Note 3. Restructuring and Other Costs Summary of Restructuring and Other Initiatives We recorded pre-tax restructuring and other costs of $5.2 and $12.9 million for the three and six months ended March 31, 2021 and $16.4 and $46.5 million for the three and six months ended March 31, 2020. These amounts are not comparable since the timing and scope of the individual actions associated with each restructuring, acquisition, integration or divestiture can vary. We present our restructuring and other costs in more detail below. The following table summarizes our Restructuring and other costs (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Restructuring $ 4.1 $ 8.0 $ 10.7 $ 32.7 Other 1.1 8.4 2.2 13.8 Restructuring and other costs $ 5.2 $ 16.4 $ 12.9 $ 46.5 Restructuring Our restructuring charges are primarily associated with restructuring portions of our operations (i.e. partial or complete plant closures), employee costs due to merger and acquisition-related workforce reductions and voluntary retirement programs in fiscal 2019 and 2020. A partial plant closure may consist of shutting down a machine and/or a workforce reduction. When we close a facility, if necessary, we recognize a write-down to reduce the carrying value of related property, plant and equipment and lease right-of-use assets (“ ROU Although specific circumstances vary, our strategy has generally been to consolidate our sales and operations into large well-equipped plants that operate at high utilization rates and take advantage of available capacity created by operational excellence initiatives and/or further optimize our system following mergers and acquisitions or a changing business environment. Therefore, we generally transfer a substantial portion of each closed plant’s assets and production to our other plants. We believe these actions have allowed us to more effectively manage our business. In our former Land and Development segment, the restructuring charges primarily consisted of severance and other employee costs associated with the wind-down of operations and lease costs. While restructuring costs are not charged to our segments and, therefore, do not reduce segment income, we highlight the segment to which the charges relate. The following table presents a summary of restructuring charges related to active restructuring initiatives that we incurred during the three and six months ended March 31, 2021 and 2020, the cumulative recorded amount since we started the initiatives and our estimate of the total we expect to incur (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Cumulative Total Expected Corrugated Packaging Net property, plant and equipment costs $ — $ 0.3 $ — $ 2.5 $ 94.4 $ 94.4 Severance and other employee costs (0.4 ) (3.5 ) (1.1 ) 3.6 51.3 51.3 Equipment and inventory relocation costs — 0.9 — 1.3 8.7 9.2 Facility carrying costs 0.2 0.4 1.0 1.0 21.9 23.4 Other costs 0.4 0.2 0.5 0.4 4.0 4.0 Restructuring total $ 0.2 $ (1.7 ) $ 0.4 $ 8.8 $ 180.3 $ 182.3 Consumer Packaging Net property, plant and equipment costs $ — $ — $ 0.2 $ 0.5 $ 35.3 $ 35.3 Severance and other employee costs 2.4 7.4 5.9 13.1 43.3 43.3 Equipment and inventory relocation costs — — 0.2 0.1 3.8 3.8 Facility carrying costs — — — — 1.0 1.3 Other costs 0.8 0.4 1.6 0.6 20.4 20.4 Restructuring total $ 3.2 $ 7.8 $ 7.9 $ 14.3 $ 103.8 $ 104.1 Land and Development Net property, plant and equipment costs $ — $ — $ — $ — $ 1.8 $ 1.8 Severance and other employee costs — — — — 13.8 13.8 Other costs — — — — 5.0 5.0 Restructuring total $ — $ — $ — $ — $ 20.6 $ 20.6 Corporate Severance and other employee costs $ (0.7 ) 1.2 0.9 8.9 $ 60.3 $ 60.3 Other costs 1.4 0.7 1.5 0.7 10.5 10.5 Restructuring total $ 0.7 $ 1.9 $ 2.4 $ 9.6 $ 70.8 $ 70.8 Total Net property, plant and equipment costs $ — $ 0.3 $ 0.2 $ 3.0 $ 131.5 $ 131.5 Severance and other employee costs 1.3 5.1 5.7 25.6 168.7 168.7 Equipment and inventory relocation costs — 0.9 0.2 1.4 12.5 13.0 Facility carrying costs 0.2 0.4 1.0 1.0 22.9 24.7 Other costs 2.6 1.3 3.6 1.7 39.9 39.9 Restructuring total $ 4.1 $ 8.0 $ 10.7 $ 32.7 $ 375.5 $ 377.8 We have defined “ Net property, plant and equipment costs Note 3 Other Costs Our other costs consist of acquisition, integration and divestiture costs. We incur costs when we acquire or divest businesses. Acquisition costs include costs associated with transactions, whether consummated or not, such as advisory, legal, accounting, valuation and other professional or consulting fees, as well as potential litigation costs associated with those activities. We incur integration costs pre- and post-acquisition that reflect work being performed to facilitate merger and acquisition integration, such as work associated with information systems and other projects, including spending to support future acquisitions, and primarily consist of professional services and labor. Divestiture costs consist primarily of similar professional fees. We consider acquisition, integration and divestiture costs to be corporate costs regardless of the segment or segments involved in the transaction. The following table presents our acquisition and integration costs (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Acquisition costs $ 0.5 $ 0.3 $ 0.7 $ 0.4 Integration costs 0.4 8.1 1.3 13.4 Divestiture costs 0.2 — 0.2 — Other total $ 1.1 $ 8.4 $ 2.2 $ 13.8 The following table summarizes the changes in the restructuring accrual, which is primarily composed of accrued severance and other employee costs, and a reconciliation of the restructuring accrual charges to the line item “ Restructuring and other costs Six Months Ended March 31, 2021 2020 Accrual at beginning of fiscal year $ 17.2 $ 32.3 Additional accruals 8.3 27.5 Payments (10.4 ) (27.3 ) Adjustment to accruals (2.5 ) (1.9 ) Foreign currency rate changes 0.1 — Accrual at March 31 $ 12.7 $ 30.6 Reconciliation of accruals and charges to restructuring and other costs (in millions): Six Months Ended March 31, 2021 2020 Additional accruals and adjustments to accruals (see table above) $ 5.8 $ 25.6 Acquisition costs 0.7 0.4 Integration costs 1.3 13.4 Divestiture costs 0.2 — Net property, plant and equipment costs 0.2 3.0 Severance and other employee costs 0.1 (0.3 ) Equipment and inventory relocation costs 0.2 1.4 Facility carrying costs 1.0 1.0 Other costs 3.4 2.0 Total restructuring and other costs $ 12.9 $ 46.5

Retirement Plans

Retirement Plans	6 Months Ended
	Mar. 31, 2021
Retirement Plans [Abstract]
Retirement Plans	Note 4. Retirement Plans We have defined benefit pension plans and other postretirement benefit plans for certain U.S. and non-U.S. employees. Certain plans were frozen for salaried and non-union hourly employees at various times in the past, and nearly all of our remaining salaried and non-union hourly employees accruing benefits ceased accruing benefits as of December 31, 2020. In addition, we participate in several multiemployer pension plans (“ MEPP MEPPs Note 5. Retirement Plans Note 5. Retirement Plans — Multiemployer Plans MEPP In the normal course of business, we evaluate our potential exposure to MEPPs, including with respect to potential withdrawal liabilities. During fiscal 2018, we submitted formal notification to withdraw from the Pace Industry Union-Management Pension Fund (“ PIUMPF Central States At March 31, 2021 and September 30, 2020, we had recorded withdrawal liabilities of $243.2 million and $252.0 million, respectively, including liabilities associated with PIUMPF. Pension and Postretirement Income / Expense The following table presents a summary of the components of net pension income (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Service cost $ 13.6 $ 14.2 $ 27.1 $ 27.3 Interest cost 46.7 49.5 93.1 99.4 Expected return on plan assets (92.3 ) (90.8 ) (184.0 ) (181.6 ) Amortization of net actuarial loss 8.0 11.8 15.9 23.7 Amortization of prior service cost 2.0 2.1 4.0 3.5 Curtailment loss — 0.4 — 0.4 Company defined benefit plan income (22.0 ) (12.8 ) (43.9 ) (27.3 ) Multiemployer and other plans 0.4 0.4 0.8 0.7 Net pension income $ (21.6 ) $ (12.4 ) $ (43.1 ) $ (26.6 ) The non-service elements of our pension and postretirement costs set forth in this Note 4. Retirement Plans We maintain other postretirement benefit plans that provide certain health care and life insurance benefits for certain salaried and hourly employees who meet specified age and service requirements as defined by the plans. The following table presents a summary of the components of the net postretirement cost (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Service cost $ 0.3 $ 0.3 $ 0.6 $ 0.7 Interest cost 1.5 1.8 2.9 3.6 Amortization of net actuarial gain (0.3 ) (0.2 ) (0.6 ) (0.4 ) Amortization of prior service credit (0.6 ) (0.7 ) (1.2 ) (1.4 ) Net postretirement cost $ 0.9 $ 1.2 $ 1.7 $ 2.5 Employer Contributions During the three and six months ended March 31, 2021, we made contributions to our qualified and supplemental defined benefit pension plans of $5.2 million and $10.8 million, respectively, and for the three and six months ended March 31, 2020, we made contributions of $4.1 million and $12.6 million, respectively. During the three and six months ended March 31, 2021, we funded an aggregate of $1.8 million and $3.1 million, respectively, and for the three and six months ended March 31, 2020, we funded an aggregate of $1.7 million and $3.7 million, respectively, to our other postretirement benefit plans.

Income Taxes

Income Taxes	6 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Note 5. Income Taxes The effective tax rate for the three and six months ended March 31, 2021 was 21.0% and 23.2%, respectively. The effective tax rate for both periods was impacted by (i) the inclusion of state taxes, (ii) tax expense related to stock-based compensation, (iii) the exclusion of tax benefits related to losses recorded by certain foreign operations, partially offset by (iv) (v) research and development tax credits. The effective tax rate for the three and six months ended March 31, 2020 was 28.0% and 26.6%, respectively. The effective tax rate for both periods was higher than the statutory federal rate primarily due to (i) the inclusion of state taxes, (ii) income derived from certain foreign jurisdictions subject to higher tax rates, (iii) the exclusion of tax benefits related to losses recorded by certain foreign operations and (iv) tax expense related to stock based compensation, partially offset by research and development tax credits.

Segment Information

Segment Information	6 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information	Note 6. We report our financial results of operations in the following two reportable segments: Corrugated Packaging, which consists of our containerboard mills, corrugated packaging and distribution operations, as well as our merchandising displays and recycling procurement operations; and Consumer Packaging, which consists of our consumer mills and food and beverage and partition operations. Prior to the completion of our monetization program in fiscal 2020, we had a third reportable segment, Land and Development, which previously sold real estate, primarily in the Charleston, SC region. Certain income and expenses are not allocated to our segments and, thus, the information that management uses to make operating decisions and assess performance does not reflect such amounts. Items not allocated are reported as non-allocated expenses or in other line items in the table below after segment income. The following tables show selected operating data for our segments (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Net sales (aggregate): Corrugated Packaging $ 2,913.4 $ 2,882.5 $ 5,777.9 $ 5,792.0 Consumer Packaging 1,589.9 1,616.3 3,185.0 3,153.2 Land and Development — — — 18.9 Total $ 4,503.3 $ 4,498.8 $ 8,962.9 $ 8,964.1 Less net sales (intersegment): Corrugated Packaging $ 18.6 $ 20.7 $ 40.6 $ 39.0 Consumer Packaging 46.9 30.8 83.0 54.1 Total $ 65.5 $ 51.5 $ 123.6 $ 93.1 Net sales (unaffiliated customers): Corrugated Packaging $ 2,894.8 $ 2,861.8 $ 5,737.3 $ 5,753.0 Consumer Packaging 1,543.0 1,585.5 3,102.0 3,099.1 Land and Development — — — 18.9 Total $ 4,437.8 $ 4,447.3 $ 8,839.3 $ 8,871.0 Segment income: Corrugated Packaging $ 205.3 $ 244.5 $ 420.3 $ 527.9 Consumer Packaging 81.2 90.8 173.7 137.0 Land and Development — — — 1.4 Segment income 286.5 335.3 594.0 666.3 Gain on sale of certain closed facilities — 5.0 0.9 5.5 Multiemployer pension withdrawal expense — (0.9 ) — (0.9 ) Restructuring and other costs (5.2 ) (16.4 ) (12.9 ) (46.5 ) Non-allocated expenses (39.5 ) (17.6 ) (63.3 ) (35.8 ) Interest expense, net (83.5 ) (97.3 ) (177.3 ) (190.8 ) Loss on extinguishment of debt — (0.5 ) (1.1 ) (0.5 ) Other (expense) income, net (13.4 ) (0.9 ) 7.4 (4.6 ) Income before income taxes $ 144.9 $ 206.7 $ 347.7 $ 392.7 Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Depreciation and amortization: Corrugated Packaging $ 229.9 $ 239.6 $ 462.2 $ 483.9 Consumer Packaging 130.1 133.2 261.1 268.5 Corporate 1.4 1.7 2.6 3.3 Total $ 361.4 $ 374.5 $ 725.9 $ 755.7 In October 2018, our containerboard and pulp mill located in Panama City, FL sustained extensive damage from Hurricane Michael. In fiscal 2019, we received the majority of our Hurricane Michael-related insurance proceeds. In the three months ended December 31, 2019, we received the remaining Hurricane Michael-related insurance proceeds of $32.3 million, of which $29.5 million was recorded as a reduction of cost of goods sold in our Corrugated Packaging segment. The remaining The insurance proceeds consisted of $11.7 million of business interruption recoveries and $20.6 million for direct costs and property damage. Our condensed consolidated statement of cash flows for the six months ended March 31, 2020 included $30.9 million in net cash provided by operating activities and $1.4 million of cash proceeds included in net cash used for investing activities related to Hurricane Michael.

Interest Expense, Net

Interest Expense, Net	6 Months Ended
	Mar. 31, 2021
Interest Income Expense Net [Abstract]
Interest Expense, Net	Note 7. The components of interest expense, net are as follows (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Interest expense $ (94.9 ) $ (112.1 ) $ (200.4 ) $ (231.3 ) Interest income 11.4 14.8 23.1 40.5 Interest expense, net $ (83.5 ) $ (97.3 ) $ (177.3 ) $ (190.8 )

Inventories

Inventories	6 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Inventories	Note 8. Inventories We value substantially all of our U.S. inventories at the lower of cost or market, with cost determined on a last-in first-out (“ LIFO FIFO The components of inventories were as follows (in millions): March 31, 2021 September 30, 2020 Finished goods and work in process $ 917.8 $ 844.2 Raw materials 784.4 772.7 Spare parts and supplies 517.9 500.3 Inventories at FIFO cost 2,220.1 2,117.2 LIFO reserve (129.2 ) (93.8 ) Net inventories $ 2,090.9 $ 2,023.4

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Property, Plant and Equipment	Note 9. Property, Plant and Equipment The components of property, plant and equipment were as follows (in millions): March 31, 2021 September 30, 2020 Property, plant and equipment at cost: Land and buildings $ 2,546.6 $ 2,524.7 Machinery and equipment 15,432.9 15,147.3 Forestlands and mineral rights 112.6 110.8 Transportation equipment 28.0 29.1 Leasehold improvements 105.9 103.6 18,226.0 17,915.5 Less: accumulated depreciation, depletion and amortization (7,653.5 ) (7,136.6 ) Property, plant and equipment, net $ 10,572.5 $ 10,778.9

Fair Value

Fair Value	6 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value	Note 10. Fair Value Assets and Liabilities Measured or Disclosed at Fair Value We estimate fair values in accordance with ASC 820, “Fair Value Measurement Note 12. Fair Value “ Note 11. Debt ”. Note 5. Retirement Plans The three and six months ended March 31, 2021, reflect a charge of $22.5 million associated with not exercising an option to purchase an additional equity interest in Grupo Gondi that was recorded in other (expense) income, net. Financial Instruments Not Recognized at Fair Value Financial instruments not recognized at fair value on a recurring or nonrecurring basis include cash and cash equivalents, accounts receivable, certain other current assets, short-term debt, accounts payable, certain other current liabilities and long-term debt. With the exception of long-term debt, the carrying amounts of these financial instruments approximate their fair values due to their short maturities. Fair Value of Nonfinancial Assets and Nonfinancial Liabilities We measure certain nonfinancial assets and nonfinancial liabilities at fair value on a nonrecurring basis. These assets and liabilities include equity method investments when they are deemed to be other-than-temporarily impaired, investments for which the fair value measurement alternative is elected, assets acquired and liabilities assumed when they are deemed to be other-than-temporarily impaired, assets acquired and liabilities assumed in a merger or an acquisition or in a nonmonetary exchange, property, plant and equipment, ROU assets related to operating leases, goodwill and other and intangible assets that are written down to fair value when they are held for sale or determined to be impaired. See “ Note 3. Restructuring and Other Costs ” for impairments associated with restructuring activities presented as “net property, plant and equipment costs”. Accounts Receivable Sales Agreements We are a party to an accounts receivable sales agreement to sell to a third party financial institution all of the short-term receivables generated from certain customer trade accounts. On September 17, 2020, we amended the then existing agreement and increased the purchase limit to $700.0 million. The terms of the amended agreement limit the balance of receivables sold to the amount available to fund such receivables sold, thereby eliminating the receivable for proceeds from the financial institution at any transfer date. Effective with the amended agreement, the facility is committed and has a term of 364 days. Transfers under the agreement meet the requirements to be accounted for as Transfers and Servicing Note 11. Debt The following table presents a summary of these accounts receivable sales agreements for the six months ended March 31, 2021 and March 31, 2020 (in millions): Six Months Ended March 31, 2021 2020 Receivable from financial institution at beginning of fiscal year $ — $ — Receivables sold to the financial institution and derecognized (1,302.8 ) (1,210.2 ) Receivables collected by financial institution 1,271.0 1,219.6 Cash proceeds from (paid to) financial institution 31.8 (9.4 ) Receivable $ — $ — Receivables sold under these were approximately $621.1 million and $589.4 million as of March 31, 2021 and September 30, 2020, respectively. Cash proceeds related to the receivables sold are included in cash from operating activities in the condensed consolidated statement of cash flows in the accounts receivable line item. While the expense recorded in connection with the sale of receivables may vary based on current rates and levels of receivables sold, the expense recorded in connection with the sale of receivables was $2.7 million and $5.7 million for the three and six months ended March 31, 2021, respectively, and $4.1 million and $8.4 million for the three and six months ended March 31, 2020, respectively, and is recorded in “other (expense) income, net” in the condensed consolidated statements of income. Although the sales are made without recourse, we maintain continuing involvement with the sold receivables as we provide collections services related to the transferred assets. The associated servicing liability is not material given the high quality of the customers underlying the receivables and the anticipated short collection period.

Debt

Debt	6 Months Ended
	Mar. 31, 2021
Debt [Abstract]
Debt	Note 11. Debt See “ Note 13. Debt The following table shows the carrying value of the individual components of our debt (in millions): March 31, 2021 September 30, 2020 Public bonds due fiscal 2022 $ 399.6 $ 399.3 Public bonds due fiscal 2023 to 2028 3,775.9 3,773.6 Public bonds due fiscal 2029 to 2033 2,772.7 2,778.9 Public bonds due fiscal 2037 to 2047 178.4 178.6 Term loan facilities 848.8 1,547.6 Revolving credit and swing facilities 370.0 250.0 Finance lease obligations 269.3 274.8 Vendor financing and commercial card programs 96.8 89.8 International and other debt 231.1 138.0 Total debt 8,942.6 9,430.6 Less: current portion of debt 549.5 222.9 Long-term debt due after one year $ 8,393.1 $ 9,207.7 A portion of the debt classified as long-term may be paid down earlier than scheduled at our discretion without penalty. Certain customary restrictive covenants govern our maximum availability under our credit facilities. We test and report our compliance with these covenants as required and were in compliance with all of our covenants at March 31, 2021. The estimated fair value of our debt was approximately $9.7 billion as of March 31, 2021 and $10.4 billion at September 30, 2020. The fair value of our long-term debt is categorized as level 2 within the fair value hierarchy and is primarily either based on quoted prices for those or similar instruments, or approximate their carrying amount as the variable interest rates reprice frequently at observable current market rates. Revolving Credit Facility On November 21, 2019, we amended our $2.0 billion unsecured revolving credit facility entered into on July 1, 2015 (the “ Revolving Credit Facility Term Loans At September 30, 2020, there was $648.9 million outstanding on the five-year On June 7, 2019, we entered into a $300.0 million credit agreement providing for a five-year On September 27, 2019, one of our wholly-owned subsidiaries, WestRock Southeast, LLC, entered into a credit agreement (the “ Farm Loan Credit Agreement seven-year Farm Loan Credit Facility WestRock RKT, LLC (“ RKT ”) WestRock MWV, LLC (“ MWV ”, the “ Guarantor Subsidiaries ”) Receivables Securitization Facility On March 12, 2021, we amended our existing $700.0 million receivables securitization agreement (the “ Receivables Securitization Facility European Revolving Credit Facility On February 26, 2021, we replaced our existing revolving credit facility with Coöperatieve Rabobank U.A., New York Branch, as administrative agent. The amendments included, among other things, increasing the facility to €600.0 million while maintaining the incremental €100.0 million accordion feature. This facility provides for a three-year February 26, 2024 March 31, 2021 Commercial Paper Program On December 7, 2018, we established an unsecured commercial paper program with WRKCo Inc. as the issuer. Under the program, we may issue short-term unsecured commercial paper notes in an aggregate principal amount at any time not to exceed $1.0 billion with up to 397-day maturities. The program has no expiration date and can be terminated by either the agent or us with not less than 30 days’ notice. Our Revolving Credit Facility is intended to backstop the commercial paper program. Amounts available under the program may be borrowed, repaid and re-borrowed from time to time. At March 31, 2021 and September 30, 2020, . Brazil Export Credit Note On January 18, 2021, we entered into a credit agreement to provide for R$500.0 million of a senior unsecured term loan of WestRock the facility are used to support the production of goods or acquisition of inputs that are essential or ancillary to export activities.

Leases

Leases	6 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Leases	Note 12. Leases We lease various real estate, including certain operating facilities, warehouses, office space and land. We also lease material handling equipment, vehicles and certain other equipment. Our total lease cost, net was $ million and $160.1 million during the , respectively. total lease cost, net was $ , respectively. We obtained $ million and $ million of ROU assets in exchange for lease liabilities during the six months ended March 31, 2021 and 2020, respectively. Supplemental Balance Sheet Information Related to Leases The table below presents supplemental balance sheet information related to leases (in millions): Condensed Consolidated Balance Sheet Caption March 31, 2021 September 30, 2020 Operating leases: Operating lease right-of-use asset Other assets $ 696.4 $ 658.6 Current operating lease liabilities Other current liabilities $ 181.9 $ 172.7 Operating lease liabilities Other long-term liabilities 573.2 545.8 Total operating lease liabilities $ 755.1 $ 718.5 Finance leases: Property, plant and equipment $ 143.0 $ 143.2 Accumulated depreciation (23.7 ) (19.1 ) Property, plant and equipment, net $ 119.3 $ 124.1 Current finance lease liabilities Current portion of debt $ 8.8 $ 9.0 Noncurrent finance lease liabilities Long-term debt due after one year 260.5 265.8 Total finance lease liabilities $ 269.3 $ 274.8 Our finance lease portfolio includes certain assets that are either fully depreciated or transferred for which the lease arrangement requires a one-time principal repayment on the maturity date of the lease obligation.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Mar. 31, 2021
Commitments And Contingencies [Abstract]
Commitments and Contingencies	Note 13. Commitments and Contingencies Health and Safety Our business involves the use of heavy equipment, machinery and chemicals and requires the performance of activities that create safety exposures. The health and safety of our teammates is our first priority, and we have established safety policies, programs, procedures and training for our manufacturing operations. We are subject to a broad range of foreign, federal, state and local laws and regulations relating to occupational health and safety, and our safety program includes measures required for compliance. In addition, our program includes the ongoing identification and elimination of workplace exposures that can lead to injuries and sharing of health and safety best practices. Failure to comply with applicable health and safety laws and regulations could subject us to fines, corrective actions or other sanctions. Certain governmental authorities in locations where we do business have established asbestos standards for the workplace. Although we do not use asbestos in manufacturing our products, asbestos containing material (“ ACM We do not believe that future compliance with occupational health and safety laws and regulations will have a material adverse effect on our results of operations, financial condition or cash flows. Environmental We are subject to numerous foreign, federal, state, local and international environmental laws and regulations, including those governing discharges to air, soil and water; the management, treatment and disposal of hazardous substances, solid waste and hazardous wastes; the investigation and remediation of contamination resulting from historical site operations; and requirements relating to the use of chemicals in packaging. We are also subject to the requirements of environmental permits and similar authorizations issued by various governmental authorities. Complex and lengthy processes may be required to obtain and renew approvals, permits, and licenses for new, existing or modified facilities. Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and emergency response procedures. Our compliance initiatives related to these laws and regulations could result in significant costs, which could negatively impact our results of operations, financial condition and cash flows. Failure to comply with environmental laws and regulations, or any permits and authorizations required thereunder, could subject us to fines, corrective action s or other sanctions. We have been named as a potentially responsible party (“ PRP CERCLA See “ Note 18. Commitments and Contingencies As of March 31, 2021, we had $4.9 million reserved for environmental liabilities on an undiscounted basis, of which $1.7 million is included in other long-term liabilities and $3.2 million is included in other current liabilities, including amounts accrued in connection with environmental obligations relating to manufacturing facilities that we have closed. We believe the liability for these matters was adequately reserved at March 31, 2021. Litigation We have been named a defendant in asbestos-related personal injury litigation. To date, the costs resulting from the litigation, including settlement costs, have not been significant. As of March 31, 2021, there were approximately 1,400 such lawsuits. We believe that we have substantial insurance coverage, subject to applicable deductibles and policy limits, with respect to asbestos claims. We also have valid defenses to these asbestos-related personal injury claims and intend to continue to defend them vigorously. Should the volume of litigation grow substantially beyond our expectations, it is possible that we could incur significant costs resolving these cases. We do not expect the resolution of pending asbestos litigation and proceedings to have a material adverse effect on our results of operations, financial condition or cash flows. In any given period or periods, however, it is possible such proceedings or matters could have an adverse effect on our results of operations, financial condition or cash flows. At March 31, 2021, we had a $13.8 million estimated liability for these matters. We are a defendant in a number of other lawsuits and claims arising out of the conduct of our business. While the ultimate results of such suits or other proceedings against us cannot be predicted with certainty, we believe the resolution of these other matters will not have a material adverse effect on our results of operations, financial condition or cash flows. Brazil Tax Liability We are challenging claims by the Brazil Federal Revenue Department that we are liable for underpayment of tax, penalties and interest in relation to a claim that a subsidiary of MeadWestvaco Corporation (the predecessor of WestRock MWV, LLC) CARF We assert that we have no liability in these matters. The total amount in dispute before CARF and in the annulment actions relating to the claimed tax deficiency was s of March 31, 2021 , including various penalties and interest. The U.S. dollar equivalent has fluctuated significantly due to changes in exchange rates. The amount of o ur uncertain tax position reserve for this matter, that excludes certain penalties, is included in the unrecognized tax benefits table. See “ Note 6. Income Taxes ” of the Notes to Consolidated Financial Statements section in the Fiscal 2020 10-K. Resolution of the uncertain tax positions could have a material adverse effect on our cash flows and results of operations or materially benefit our results of operations in future periods depending upon their ultimate resolution. Guarantees We make certain guarantees in the normal course of conducting our operations, for compliance with certain laws and regulations, or in connection with certain business dispositions. The guarantees include items such as funding of net losses in proportion to our ownership share of certain joint ventures, debt guarantees related to certain unconsolidated entities acquired in acquisitions, indemnifications of lessors in certain facilities and equipment operating leases for items such as additional taxes being assessed due to a change in tax law and certain other agreements. We estimate our exposure to these matters could be approximately $50 million. As of March 31, 2021, we had recorded $9.6 million for the estimated fair value of these guarantees. We are unable to estimate our maximum exposure under operating leases because it is dependent on potential changes in the tax laws; however, we believe our exposure related to guarantees would not have a material impact on our results of operations, financial condition or cash flows. Indirect Tax Claim In March 2017, the Supreme Court of Brazil issued a decision concluding that certain state value added tax should not be included in the calculation of federal gross receipts taxes. Subsequently, in fiscal 2019 and 2020, the Supreme Court of Brazil rendered favorable decisions on eight of our cases granting us the right to recover certain state value added tax. The tax authorities in Brazil have filed a Motion of Clarification with the Supreme Court of Brazil and the timing of the decision is unknown at this time. However, based on our evaluation and the opinion of our tax and legal advisors, we believe the decision reduced our gross receipts tax in Brazil prospectively and retrospectively, and will allow us to recover tax amounts collected by the government. Due to the volume of invoices being reviewed (January 2002 to September 2019), we have recorded the estimated recoveries across several periods beginning in the fourth quarter of fiscal 2019 as we have reviewed the documents and the amount has become estimable. In the three months ended March 31, 2020, we recorded a receivable for our expected recovery and interest that consisted primarily of a $0.4 million reduction of cost of goods sold and a $0.9 million reduction of interest expense, net. In the six months ended March 31, 2021 and 2020, we recorded a receivable for our expected recovery and interest that consisted primarily of a $0.6 million and $23.5 million reduction of cost of goods sold and a $0.3 million and $11.6 million reduction of interest expense, net, respectively. We are monitoring the status of our remaining cases, and subject to the resolution in the courts, we may record additional amounts in future periods.

Equity and Other Comprehensive

Equity and Other Comprehensive Income (Loss)	6 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Equity and Other Comprehensive Income (Loss)	Note 14. Equity and Other Comprehensive Income (Loss) Equity Stock Repurchase Program In July 2015, our board of directors authorized a repurchase program of up to 40.0 million shares of our Common Stock, representing approximately 15% of our outstanding common stock, par value $ per share (“ Common Stock ”) Accumulated Other Comprehensive Loss The tables below summarize the changes in accumulated other comprehensive loss, net of tax, by component for the six months ended March 31, 2021 and March 31, 2020 (in millions): Cash Flow Hedges Defined Benefit Pension and Postretirement Plans Foreign Currency Items Total (1) Balance at September 30, 2020 $ (5.6 ) $ (727.7 ) $ (586.6 ) $ (1,319.9 ) Other comprehensive (loss) income before reclassifications (0.1 ) — 109.5 109.4 Amounts reclassified from accumulated other comprehensive loss 2.9 13.3 — 16.2 Net current period other comprehensive income 2.8 13.3 109.5 125.6 Balance at March 31, 2021 $ (2.8 ) $ (714.4 ) $ (477.1 ) $ (1,194.3 ) (1) Cash Flow Hedges Defined Benefit Pension and Postretirement Plans Foreign Currency Items Total (1) Balance at September 30, 2019 $ 0.7 $ (698.0 ) $ (371.9 ) $ (1,069.2 ) Other comprehensive loss before reclassifications (9.4 ) — (286.6 ) (296.0 ) Amounts reclassified from accumulated other comprehensive loss 1.1 18.5 — 19.6 Net current period other comprehensive (loss) income (8.3 ) 18.5 (286.6 ) (276.4 ) Reclassification of stranded tax effects — (73.4 ) — (73.4 ) Balance at March 31, 2020 $ (7.6 ) $ (752.9 ) $ (658.5 ) $ (1,419.0 ) (1) The net of tax amounts were determined using the jurisdictional statutory rates, and reflect effective tax rates averaging 24% to 25% for the six months ended March 31, 2021 and 26% to 27% for the six months ended March 31, 2020. Although we are impacted by the exchange rates of a number of currencies, foreign currency translation adjustments recorded in accumulated other comprehensive loss for the six months ended March 31, 2021 were primarily due to gains in the Canadian dollar, Mexican Peso and British Pound partially offset by losses in the Brazilian Real, each against the U.S. dollar. Foreign currency translation gains recorded in accumulated other comprehensive loss for the six months ended March 31, 2020 were primarily due to losses in the Brazilian Real, Mexican Peso, Canadian dollar, Australian dollar and Euro partially offset by gains in the British Pound, each against the U.S. dollar. The following table summarizes the reclassifications out of accumulated other comprehensive loss by component (in millions): Three Months Ended Three Months Ended March 31, 2021 March 31, 2020 Pretax Tax Net of Tax Pretax Tax Net of Tax Amortization of defined benefit pension and postretirement items: (1) Actuarial losses (2) $ (7.4 ) $ 1.7 $ (5.7 ) $ (11.5 ) $ 3.1 $ (8.4 ) Prior service costs (2) (1.3 ) 0.3 (1.0 ) (1.3 ) 0.3 (1.0 ) Subtotal defined benefit plans (8.7 ) 2.0 (6.7 ) (12.8 ) 3.4 (9.4 ) Derivative Instruments: (1) Interest rate swap hedge (loss) gain (3) (1.9 ) 0.5 (1.4 ) 0.3 — 0.3 Natural gas commodity hedge loss (4) — — — (3.7 ) 1.0 (2.7 ) Subtotal cash flow hedges (1.9 ) 0.5 (1.4 ) (3.4 ) 1.0 (2.4 ) Total reclassifications for the period $ (10.6 ) $ 2.5 $ (8.1 ) $ (16.2 ) $ 4.4 $ (11.8 ) (1) (2) Note 4. Retirement Plans (3) These accumulated other comprehensive income components are included in Interest expense, net. (4) These accumulated other comprehensive income components are included in Cost of goods sold. Six Months Ended Six Months Ended March 31, 2021 March 31, 2020 Pretax Tax Net of Tax Pretax Tax Net of Tax Amortization of defined benefit pension and postretirement items: (1) Actuarial losses (2) $ (14.8 ) $ 3.6 $ (11.2 ) $ (23.1 ) $ 6.1 $ (17.0 ) Prior service costs (2) (2.8 ) 0.7 (2.1 ) (2.0 ) 0.5 (1.5 ) Reclassification of stranded tax effects (3) — — — — 73.4 73.4 Subtotal defined benefit plans (17.6 ) 4.3 (13.3 ) (25.1 ) 80.0 54.9 Derivative Instruments: (1) Interest rate swap hedge (loss) gain (4) (3.9 ) 1.0 (2.9 ) 1.0 (0.2 ) 0.8 Natural gas commodity hedge gain (5) — — — (2.6 ) 0.7 (1.9 ) Subtotal cash flow hedges (3.9 ) 1.0 (2.9 ) (1.6 ) 0.5 (1.1 ) Total reclassifications for the period $ (21.5 ) $ 5.3 $ (16.2 ) $ (26.7 ) $ 80.5 $ 53.8 (1) (2) Note 4. Retirement Plans (3) . (4) These accumulated other comprehensive income components are included in Interest expense, net. (5) These accumulated other comprehensive income components are included in Cost of goods sold.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Note 15. Earnings Per Share The restricted stock awards that we grant to non-employee directors are considered participating securities as they receive non-forfeitable rights to dividends at the same rate as our Common Stock. As participating securities, we include these instruments in the earnings allocation in computing earnings per share under the two-class method described in ASC 260, “ Earnings per Share Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Numerator: Net income attributable to common stockholders $ 112.5 $ 148.1 $ 264.5 $ 286.6 Less: Distributed and undistributed income available to participating securities (0.1 ) (0.1 ) (0.1 ) (0.1 ) Distributed and undistributed income available to common stockholders $ 112.4 $ 148.0 $ 264.4 $ 286.5 Denominator: Basic weighted average shares outstanding 264.9 259.0 263.8 258.6 Effect of dilutive stock options and non- participating securities 2.1 1.2 2.1 1.5 Diluted weighted average shares outstanding 267.0 260.2 265.9 260.1 Basic earnings per share attributable to common stockholders $ 0.42 $ 0.57 $ 1.00 $ 1.11 Diluted earnings per share attributable to common stockholders $ 0.42 $ 0.57 $ 0.99 $ 1.10 Approximately 0.6 million and 1.8 million awards in the three months ended March 31, 2021 and March 31, 2020, respectively, were not included in computing diluted earnings per share because the effect would have been antidilutive. Approximately 0.6 million and 1.4 million awards in the six months ended March 31, 2021 and March 31, 2020, respectively, were not included in computing diluted earnings per share because the effect would have been antidilutive.

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	6 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Our independent registered public accounting firm has not audited the accompanying interim financial statements. We derived the condensed consolidated balance sheet at September 30, 2020 from the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended September 30, 2020 (the “ Fiscal 2020 Form 10-K We have condensed or omitted certain notes and other information from the interim financial statements presented in this report. Therefore, these interim financial statements should be read in conjunction with the Fiscal 2020 Form 10-K. The results for the three and six months ended March 31, 2021 are not necessarily indicative of results that may be expected for the full year.
Reclassifications and Adjustments	Reclassifications and Adjustments Certain amounts in prior periods have been reclassified to conform with the current year presentation.
COVID-19 Pandemic	COVID-19 Pandemic The global impact of the COVID-19 pandemic (“ COVID-19 At March 31, 2021, we evaluated the then current economic environment, including our assessment of the impact of COVID-19, as well as the ransomware incident discussed below, and there were no indicators of impairment of our long-lived assets, including goodwill, that required a quantitative test to be performed. Our estimates involve numerous assumptions about the future growth and potential volatility in revenues and costs, capital expenditures, industry and global economic factors, interest rate environment and future business strategy. Accordingly, our accounting estimates may materially change from period to period due to changing market factors, including those driven by COVID-19. We will continue to monitor future events, changes in circumstances and the potential impact thereof, including performing interim goodwill impairment assessments, as warranted. If actual results are not consistent with our assumptions and estimates, we may be exposed to impairment losses that could be material. See “ Note 1. Description of Business and Summary of Significant Accounting Policies — Goodwill and Long-Lived Assets ” in the Fiscal 2020 Form 10-K for additional information regarding the results of, and our methods and assumptions applied to perform, our goodwill impairment testing in fiscal 2020.
Ransomware Incident	Ransomware Incident As previously disclosed, on January 23, 2021 we detected a ransomware incident impacting certain of our systems. Promptly upon our detection of this incident, we initiated response and containment protocols and our security teams, supplemented by leading cyber defense firms, worked to remediate this incident. These actions included taking preventative measures, including shutting down certain systems out of an abundance of caution, as well as taking steps to supplement existing security monitoring, scanning and protective measures. We notified law enforcement and contacted our customers to apprise them of the situation. We undertook extensive efforts to identify, contain and recover from this incident quickly and securely. Our teams worked to maintain our business operations and minimize the impact on our customers and teammates. All systems are back in service. All of our mills and converting locations began producing and shipping paper and packaging at pre-ransomware levels in March 2021 or earlier. Our mill system production was approximately 115,000 tons lower than planned for the quarter ended March 31, 2021 as a result of this incident. While shipments from some of our facilities initially lagged behind production levels, this gap closed as systems were restored during the second quarter of fiscal 2021. In locations where technology issues were identified, we used alternative methods, in many cases manual methods, to process and ship orders. We systematically brought our information systems back online in a controlled, phased approach. We estimate the segment income impact of the lost sales and operational disruption of this incident on our operations in the second quarter of fiscal 2021 to be approximately $50 million, as well as approximately $20 million of ransomware recovery costs, primarily professional fees. We estimate that the total insurance claim will be approximately $75 million. We expect to recover substantially all of the ransomware losses from cyber and business interruption insurance in future periods. Disputes over the extent of insurance coverage for claims are not uncommon, and there will be a time lag between the initial incurrence of costs and the receipt of any insurance proceeds. While the impact of lost sales and operational disruption is behind us, we expect to incur some additional recovery costs in the second half of fiscal 2021, albeit at a diminished rate. We are making information technology investments that we had planned to make in future periods in order to further strengthen our information security infrastructure. We engaged a leading cybersecurity defense firm that completed a forensics investigation of the ransomware incident and we are taking appropriate actions in response to the findings. For example, in the short-term, we reset all credentials Company-wide and strengthened security tooling across our servers and workstations. In the long-term, we are continuing to advance the maturity and effectiveness of our information security resiliency strategy and capabilities. Our technology team has accelerated its roadmap to further strengthen the resiliency of our information security infrastructure across the Company that aims to enable us to detect, respond and recover more quickly from security and technical incidents. More specifically, we plan to take actions to improve our security monitoring capabilities and enhance the information security within our mills and plants.
Significant Accounting Policies	Significant Accounting Policies See “ Note 1. Description of Business and Summary of Significant Accounting Policies
New Accounting Standards - Recently Adopted	New Accounting Standards — Recently Adopted In November 2018, the Financial Accounting Standards Board (“ FASB ASU Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 ASC Collaborative arrangements ASC Revenues from Contracts with Customers ASC 606 In October 2018, the FASB issued ASU 2018-17 “ Consolidation: Targeted Improvements to Related Party Guidance for Variable Interest Entities ”. This ASU changes how entities evaluate decision-making fees under the variable interest entity guidance. To determine whether decision-making fees represent a variable interest, an entity considers indirect interests held through related parties under common control on a proportionate basis, rather than in their entirety, as currently required under generally accepted accounting principles in the U.S. (“ GAAP ”). We adopted the provisions of ASU 2018-17 on October 1, 2020. The adoption did not have a material impact on our consolidated financial statements. In August 2018, the FASB issued 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 In August 2018, the FASB issued ASU 2018-14 “ Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans In June 2016, the FASB issued ASU 2016-13 “ Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) ASU 2016-13 and replaces the incurred loss model with a model that reflects expected credit losses Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments ASU 2019-04 “Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief” ASU 2019-05 Codification Improvements to Topic 326, Financial Instruments – Credit Losses ASU 2019-11 Financial Instruments – Credit Losses (Topic 326) and Leases (Topic 842) ASU 2020-02 modified retrospective transition approach of resulted in us recognizing
New Accounting Standards - Recently Issued	New Accounting Standards — Recently Issued In March 2020, the FASB issued ASU 2020-04 “ Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting” LIBOR In December 2019, the FASB issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Mar. 31, 2021
Revenue From Contract With Customer [Abstract]
Schedule of Disaggregates Revenue by Geographical Market and Product Type (Segment)	The tables below disaggregate our revenue by geographical market and product type (segment). Three Months Ended March 31, 2021 (In millions) Corrugated Packaging Consumer Packaging Intersegment Sales Total Primary Geographical Markets North America $ 2,797.1 $ 1,231.7 $ (65.3 ) $ 3,963.5 South America 96.5 23.1 — 119.6 Europe 1.1 265.9 — 267.0 Asia Pacific 18.7 69.2 (0.2 ) 87.7 Total $ 2,913.4 $ 1,589.9 $ (65.5 ) $ 4,437.8 Six Months Ended March 31, 2021 (In millions) Corrugated Packaging Consumer Packaging Intersegment Sales Total Primary Geographical Markets North America $ 5,567.3 $ 2,485.7 $ (123.2 ) $ 7,929.8 South America 177.5 45.3 — 222.8 Europe 2.0 515.2 (0.1 ) 517.1 Asia Pacific 31.1 138.8 (0.3 ) 169.6 Total $ 5,777.9 $ 3,185.0 $ (123.6 ) $ 8,839.3 Three Months Ended March 31, 2020 (In millions) Corrugated Packaging Consumer Packaging Land and Development Intersegment Sales Total Primary Geographical Markets North America $ 2,765.7 $ 1,281.6 $ — $ (51.4 ) $ 3,995.9 South America 100.7 18.8 — — 119.5 Europe 2.5 253.4 — — 255.9 Asia Pacific 13.6 62.5 — (0.1 ) 76.0 Total $ 2,882.5 $ 1,616.3 $ — $ (51.5 ) $ 4,447.3 Six Months Ended March 31, 2020 (In millions) Corrugated Packaging Consumer Packaging Land and Development Intersegment Sales Total Primary Geographical Markets North America $ 5,554.6 $ 2,480.4 $ 18.9 $ (92.9 ) $ 7,961.0 South America 208.3 38.8 — — 247.1 Europe 4.3 498.0 — — 502.3 Asia Pacific 24.8 136.0 — (0.2 ) 160.6 Total $ 5,792.0 $ 3,153.2 $ 18.9 $ (93.1 ) $ 8,871.0
Summary of Opening and Closing Balances of Contract Assets and Contract Liabilities	The opening and closing balances of our contract assets and contract liabilities are as follows. Contract assets and contract liabilities are reported within Other current assets and Other current liabilities, respectively, on the condensed consolidated balance sheet. (In millions) Contract Assets (Short-Term) Contract Liabilities (Short-Term) Beginning balance - October 1, 2020 $ 185.8 $ 12.0 Ending balance - March 31, 2021 191.1 21.9 Increase $ 5.3 $ 9.9

Restructuring and Other Costs (

Restructuring and Other Costs (Tables)	6 Months Ended
	Mar. 31, 2021
Restructuring And Other Costs [Abstract]
Schedule of Restructuring and Other Costs	The following table summarizes our Restructuring and other costs (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Restructuring $ 4.1 $ 8.0 $ 10.7 $ 32.7 Other 1.1 8.4 2.2 13.8 Restructuring and other costs $ 5.2 $ 16.4 $ 12.9 $ 46.5
Schedule of Restructuring Charges Related to Active Restructuring Initiatives	The following table presents a summary of restructuring charges related to active restructuring initiatives that we incurred during the three and six months ended March 31, 2021 and 2020, the cumulative recorded amount since we started the initiatives and our estimate of the total we expect to incur (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Cumulative Total Expected Corrugated Packaging Net property, plant and equipment costs $ — $ 0.3 $ — $ 2.5 $ 94.4 $ 94.4 Severance and other employee costs (0.4 ) (3.5 ) (1.1 ) 3.6 51.3 51.3 Equipment and inventory relocation costs — 0.9 — 1.3 8.7 9.2 Facility carrying costs 0.2 0.4 1.0 1.0 21.9 23.4 Other costs 0.4 0.2 0.5 0.4 4.0 4.0 Restructuring total $ 0.2 $ (1.7 ) $ 0.4 $ 8.8 $ 180.3 $ 182.3 Consumer Packaging Net property, plant and equipment costs $ — $ — $ 0.2 $ 0.5 $ 35.3 $ 35.3 Severance and other employee costs 2.4 7.4 5.9 13.1 43.3 43.3 Equipment and inventory relocation costs — — 0.2 0.1 3.8 3.8 Facility carrying costs — — — — 1.0 1.3 Other costs 0.8 0.4 1.6 0.6 20.4 20.4 Restructuring total $ 3.2 $ 7.8 $ 7.9 $ 14.3 $ 103.8 $ 104.1 Land and Development Net property, plant and equipment costs $ — $ — $ — $ — $ 1.8 $ 1.8 Severance and other employee costs — — — — 13.8 13.8 Other costs — — — — 5.0 5.0 Restructuring total $ — $ — $ — $ — $ 20.6 $ 20.6 Corporate Severance and other employee costs $ (0.7 ) 1.2 0.9 8.9 $ 60.3 $ 60.3 Other costs 1.4 0.7 1.5 0.7 10.5 10.5 Restructuring total $ 0.7 $ 1.9 $ 2.4 $ 9.6 $ 70.8 $ 70.8 Total Net property, plant and equipment costs $ — $ 0.3 $ 0.2 $ 3.0 $ 131.5 $ 131.5 Severance and other employee costs 1.3 5.1 5.7 25.6 168.7 168.7 Equipment and inventory relocation costs — 0.9 0.2 1.4 12.5 13.0 Facility carrying costs 0.2 0.4 1.0 1.0 22.9 24.7 Other costs 2.6 1.3 3.6 1.7 39.9 39.9 Restructuring total $ 4.1 $ 8.0 $ 10.7 $ 32.7 $ 375.5 $ 377.8
Schedule of Acquisition and Integration Costs	The following table presents our acquisition and integration costs (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Acquisition costs $ 0.5 $ 0.3 $ 0.7 $ 0.4 Integration costs 0.4 8.1 1.3 13.4 Divestiture costs 0.2 — 0.2 — Other total $ 1.1 $ 8.4 $ 2.2 $ 13.8
Schedule of Changes in Restructuring Accrual and Reconciliation of Accrual Charges	The following table summarizes the changes in the restructuring accrual, which is primarily composed of accrued severance and other employee costs, and a reconciliation of the restructuring accrual charges to the line item “ Restructuring and other costs Six Months Ended March 31, 2021 2020 Accrual at beginning of fiscal year $ 17.2 $ 32.3 Additional accruals 8.3 27.5 Payments (10.4 ) (27.3 ) Adjustment to accruals (2.5 ) (1.9 ) Foreign currency rate changes 0.1 — Accrual at March 31 $ 12.7 $ 30.6 Reconciliation of accruals and charges to restructuring and other costs (in millions): Six Months Ended March 31, 2021 2020 Additional accruals and adjustments to accruals (see table above) $ 5.8 $ 25.6 Acquisition costs 0.7 0.4 Integration costs 1.3 13.4 Divestiture costs 0.2 — Net property, plant and equipment costs 0.2 3.0 Severance and other employee costs 0.1 (0.3 ) Equipment and inventory relocation costs 0.2 1.4 Facility carrying costs 1.0 1.0 Other costs 3.4 2.0 Total restructuring and other costs $ 12.9 $ 46.5

Retirement Plans (Tables)

Retirement Plans (Tables)	6 Months Ended
	Mar. 31, 2021
Retirement Plans [Abstract]
Summary of Components of Net Pension Income and Summary of Components of Postretirement Benefit Cost	Pension and Postretirement Income / Expense The following table presents a summary of the components of net pension income (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Service cost $ 13.6 $ 14.2 $ 27.1 $ 27.3 Interest cost 46.7 49.5 93.1 99.4 Expected return on plan assets (92.3 ) (90.8 ) (184.0 ) (181.6 ) Amortization of net actuarial loss 8.0 11.8 15.9 23.7 Amortization of prior service cost 2.0 2.1 4.0 3.5 Curtailment loss — 0.4 — 0.4 Company defined benefit plan income (22.0 ) (12.8 ) (43.9 ) (27.3 ) Multiemployer and other plans 0.4 0.4 0.8 0.7 Net pension income $ (21.6 ) $ (12.4 ) $ (43.1 ) $ (26.6 ) Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Service cost $ 0.3 $ 0.3 $ 0.6 $ 0.7 Interest cost 1.5 1.8 2.9 3.6 Amortization of net actuarial gain (0.3 ) (0.2 ) (0.6 ) (0.4 ) Amortization of prior service credit (0.6 ) (0.7 ) (1.2 ) (1.4 ) Net postretirement cost $ 0.9 $ 1.2 $ 1.7 $ 2.5

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Certain Operating Data for Segments	The following tables show selected operating data for our segments (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Net sales (aggregate): Corrugated Packaging $ 2,913.4 $ 2,882.5 $ 5,777.9 $ 5,792.0 Consumer Packaging 1,589.9 1,616.3 3,185.0 3,153.2 Land and Development — — — 18.9 Total $ 4,503.3 $ 4,498.8 $ 8,962.9 $ 8,964.1 Less net sales (intersegment): Corrugated Packaging $ 18.6 $ 20.7 $ 40.6 $ 39.0 Consumer Packaging 46.9 30.8 83.0 54.1 Total $ 65.5 $ 51.5 $ 123.6 $ 93.1 Net sales (unaffiliated customers): Corrugated Packaging $ 2,894.8 $ 2,861.8 $ 5,737.3 $ 5,753.0 Consumer Packaging 1,543.0 1,585.5 3,102.0 3,099.1 Land and Development — — — 18.9 Total $ 4,437.8 $ 4,447.3 $ 8,839.3 $ 8,871.0 Segment income: Corrugated Packaging $ 205.3 $ 244.5 $ 420.3 $ 527.9 Consumer Packaging 81.2 90.8 173.7 137.0 Land and Development — — — 1.4 Segment income 286.5 335.3 594.0 666.3 Gain on sale of certain closed facilities — 5.0 0.9 5.5 Multiemployer pension withdrawal expense — (0.9 ) — (0.9 ) Restructuring and other costs (5.2 ) (16.4 ) (12.9 ) (46.5 ) Non-allocated expenses (39.5 ) (17.6 ) (63.3 ) (35.8 ) Interest expense, net (83.5 ) (97.3 ) (177.3 ) (190.8 ) Loss on extinguishment of debt — (0.5 ) (1.1 ) (0.5 ) Other (expense) income, net (13.4 ) (0.9 ) 7.4 (4.6 ) Income before income taxes $ 144.9 $ 206.7 $ 347.7 $ 392.7 Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Depreciation and amortization: Corrugated Packaging $ 229.9 $ 239.6 $ 462.2 $ 483.9 Consumer Packaging 130.1 133.2 261.1 268.5 Corporate 1.4 1.7 2.6 3.3 Total $ 361.4 $ 374.5 $ 725.9 $ 755.7

Interest Expense, Net (Tables)

Interest Expense, Net (Tables)	6 Months Ended
	Mar. 31, 2021
Interest Income Expense Net [Abstract]
Summary of Components of Interest Expense, Net	The components of interest expense, net are as follows (in millions): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Interest expense $ (94.9 ) $ (112.1 ) $ (200.4 ) $ (231.3 ) Interest income 11.4 14.8 23.1 40.5 Interest expense, net $ (83.5 ) $ (97.3 ) $ (177.3 ) $ (190.8 )

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventories	The components of inventories were as follows (in millions): March 31, 2021 September 30, 2020 Finished goods and work in process $ 917.8 $ 844.2 Raw materials 784.4 772.7 Spare parts and supplies 517.9 500.3 Inventories at FIFO cost 2,220.1 2,117.2 LIFO reserve (129.2 ) (93.8 ) Net inventories $ 2,090.9 $ 2,023.4

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Schedule of Property, Plant and Equipment	The components of property, plant and equipment were as follows (in millions): March 31, 2021 September 30, 2020 Property, plant and equipment at cost: Land and buildings $ 2,546.6 $ 2,524.7 Machinery and equipment 15,432.9 15,147.3 Forestlands and mineral rights 112.6 110.8 Transportation equipment 28.0 29.1 Leasehold improvements 105.9 103.6 18,226.0 17,915.5 Less: accumulated depreciation, depletion and amortization (7,653.5 ) (7,136.6 ) Property, plant and equipment, net $ 10,572.5 $ 10,778.9

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Summary of Accounts Receivable Sales Agreement	The following table presents a summary of these accounts receivable sales agreements for the six months ended March 31, 2021 and March 31, 2020 (in millions): Six Months Ended March 31, 2021 2020 Receivable from financial institution at beginning of fiscal year $ — $ — Receivables sold to the financial institution and derecognized (1,302.8 ) (1,210.2 ) Receivables collected by financial institution 1,271.0 1,219.6 Cash proceeds from (paid to) financial institution 31.8 (9.4 ) Receivable $ — $ —

Debt (Tables)

Debt (Tables)	6 Months Ended
	Mar. 31, 2021
Debt [Abstract]
Schedule of Carrying Value of Individual Components of Debt	The following table shows the carrying value of the individual components of our debt (in millions): March 31, 2021 September 30, 2020 Public bonds due fiscal 2022 $ 399.6 $ 399.3 Public bonds due fiscal 2023 to 2028 3,775.9 3,773.6 Public bonds due fiscal 2029 to 2033 2,772.7 2,778.9 Public bonds due fiscal 2037 to 2047 178.4 178.6 Term loan facilities 848.8 1,547.6 Revolving credit and swing facilities 370.0 250.0 Finance lease obligations 269.3 274.8 Vendor financing and commercial card programs 96.8 89.8 International and other debt 231.1 138.0 Total debt 8,942.6 9,430.6 Less: current portion of debt 549.5 222.9 Long-term debt due after one year $ 8,393.1 $ 9,207.7

Leases (Tables)

Leases (Tables)	6 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Summary of Supplemental Balance Sheet Information Related to Leases	Supplemental Balance Sheet Information Related to Leases The table below presents supplemental balance sheet information related to leases (in millions): Condensed Consolidated Balance Sheet Caption March 31, 2021 September 30, 2020 Operating leases: Operating lease right-of-use asset Other assets $ 696.4 $ 658.6 Current operating lease liabilities Other current liabilities $ 181.9 $ 172.7 Operating lease liabilities Other long-term liabilities 573.2 545.8 Total operating lease liabilities $ 755.1 $ 718.5 Finance leases: Property, plant and equipment $ 143.0 $ 143.2 Accumulated depreciation (23.7 ) (19.1 ) Property, plant and equipment, net $ 119.3 $ 124.1 Current finance lease liabilities Current portion of debt $ 8.8 $ 9.0 Noncurrent finance lease liabilities Long-term debt due after one year 260.5 265.8 Total finance lease liabilities $ 269.3 $ 274.8

Equity and Other Comprehensiv_2

Equity and Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Loss, Net of Tax	The tables below summarize the changes in accumulated other comprehensive loss, net of tax, by component for the six months ended March 31, 2021 and March 31, 2020 (in millions): Cash Flow Hedges Defined Benefit Pension and Postretirement Plans Foreign Currency Items Total (1) Balance at September 30, 2020 $ (5.6 ) $ (727.7 ) $ (586.6 ) $ (1,319.9 ) Other comprehensive (loss) income before reclassifications (0.1 ) — 109.5 109.4 Amounts reclassified from accumulated other comprehensive loss 2.9 13.3 — 16.2 Net current period other comprehensive income 2.8 13.3 109.5 125.6 Balance at March 31, 2021 $ (2.8 ) $ (714.4 ) $ (477.1 ) $ (1,194.3 ) (1) Cash Flow Hedges Defined Benefit Pension and Postretirement Plans Foreign Currency Items Total (1) Balance at September 30, 2019 $ 0.7 $ (698.0 ) $ (371.9 ) $ (1,069.2 ) Other comprehensive loss before reclassifications (9.4 ) — (286.6 ) (296.0 ) Amounts reclassified from accumulated other comprehensive loss 1.1 18.5 — 19.6 Net current period other comprehensive (loss) income (8.3 ) 18.5 (286.6 ) (276.4 ) Reclassification of stranded tax effects — (73.4 ) — (73.4 ) Balance at March 31, 2020 $ (7.6 ) $ (752.9 ) $ (658.5 ) $ (1,419.0 ) (1)
Summary of Reclassification out of Accumulated Other Comprehensive Loss	The following table summarizes the reclassifications out of accumulated other comprehensive loss by component (in millions): Three Months Ended Three Months Ended March 31, 2021 March 31, 2020 Pretax Tax Net of Tax Pretax Tax Net of Tax Amortization of defined benefit pension and postretirement items: (1) Actuarial losses (2) $ (7.4 ) $ 1.7 $ (5.7 ) $ (11.5 ) $ 3.1 $ (8.4 ) Prior service costs (2) (1.3 ) 0.3 (1.0 ) (1.3 ) 0.3 (1.0 ) Subtotal defined benefit plans (8.7 ) 2.0 (6.7 ) (12.8 ) 3.4 (9.4 ) Derivative Instruments: (1) Interest rate swap hedge (loss) gain (3) (1.9 ) 0.5 (1.4 ) 0.3 — 0.3 Natural gas commodity hedge loss (4) — — — (3.7 ) 1.0 (2.7 ) Subtotal cash flow hedges (1.9 ) 0.5 (1.4 ) (3.4 ) 1.0 (2.4 ) Total reclassifications for the period $ (10.6 ) $ 2.5 $ (8.1 ) $ (16.2 ) $ 4.4 $ (11.8 ) (1) (2) Note 4. Retirement Plans (3) These accumulated other comprehensive income components are included in Interest expense, net. (4) These accumulated other comprehensive income components are included in Cost of goods sold. Six Months Ended Six Months Ended March 31, 2021 March 31, 2020 Pretax Tax Net of Tax Pretax Tax Net of Tax Amortization of defined benefit pension and postretirement items: (1) Actuarial losses (2) $ (14.8 ) $ 3.6 $ (11.2 ) $ (23.1 ) $ 6.1 $ (17.0 ) Prior service costs (2) (2.8 ) 0.7 (2.1 ) (2.0 ) 0.5 (1.5 ) Reclassification of stranded tax effects (3) — — — — 73.4 73.4 Subtotal defined benefit plans (17.6 ) 4.3 (13.3 ) (25.1 ) 80.0 54.9 Derivative Instruments: (1) Interest rate swap hedge (loss) gain (4) (3.9 ) 1.0 (2.9 ) 1.0 (0.2 ) 0.8 Natural gas commodity hedge gain (5) — — — (2.6 ) 0.7 (1.9 ) Subtotal cash flow hedges (3.9 ) 1.0 (2.9 ) (1.6 ) 0.5 (1.1 ) Total reclassifications for the period $ (21.5 ) $ 5.3 $ (16.2 ) $ (26.7 ) $ 80.5 $ 53.8 (1) (2) Note 4. Retirement Plans (3) . (4) These accumulated other comprehensive income components are included in Interest expense, net. (5) These accumulated other comprehensive income components are included in Cost of goods sold.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of basic and diluted earnings per share under the two-class method (in millions, except per share data): Three Months Ended Six Months Ended March 31, March 31, 2021 2020 2021 2020 Numerator: Net income attributable to common stockholders $ 112.5 $ 148.1 $ 264.5 $ 286.6 Less: Distributed and undistributed income available to participating securities (0.1 ) (0.1 ) (0.1 ) (0.1 ) Distributed and undistributed income available to common stockholders $ 112.4 $ 148.0 $ 264.4 $ 286.5 Denominator: Basic weighted average shares outstanding 264.9 259.0 263.8 258.6 Effect of dilutive stock options and non- participating securities 2.1 1.2 2.1 1.5 Diluted weighted average shares outstanding 267.0 260.2 265.9 260.1 Basic earnings per share attributable to common stockholders $ 0.42 $ 0.57 $ 1.00 $ 1.11 Diluted earnings per share attributable to common stockholders $ 0.42 $ 0.57 $ 0.99 $ 1.10

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies - Additional Information (Details) $ in Millions	Oct. 01, 2020USD ($)	Mar. 31, 2021USD ($)T
Basis of Presentation and Significant Accounting Policies [Line Items]
Lost production from ransomware incident to date | T		115,000
Impact of lost sales and operational disruption		$ 50
Ransomware recovery costs		20
Expected insurance claim		$ 75
ASU 2016-13 [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Reclassification of adoption effect of credit loss standard to retained earnings	$ 3.8

Revenue Recognition - Additiona

Revenue Recognition - Additional Information (Details)	12 Months Ended
	Sep. 30, 2021USD ($)
Scenario Forecast [Member]
Disaggregation Of Revenue [Line Items]
Land and development sales	$ 0

Revenue Recognition - Schedule

Revenue Recognition - Schedule of Disaggregates Revenue by Geographical Market and Product Type (Segment) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Net sales	$ 4,437.8	$ 4,447.3	$ 8,839.3	$ 8,871
Corrugated Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	2,913.4	2,882.5	5,777.9	5,792
Consumer Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,589.9	1,616.3	3,185	3,153.2
Land and Development [Member]
Disaggregation Of Revenue [Line Items]
Net sales				18.9
Intersegment Sales [Member]
Disaggregation Of Revenue [Line Items]
Net sales	(65.5)	(51.5)	(123.6)	(93.1)
Intersegment Sales [Member] | Corrugated Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	(18.6)	(20.7)	(40.6)	(39)
Intersegment Sales [Member] | Consumer Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	(46.9)	(30.8)	(83)	(54.1)
North America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	3,963.5	3,995.9	7,929.8	7,961
North America [Member] | Corrugated Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	2,797.1	2,765.7	5,567.3	5,554.6
North America [Member] | Consumer Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,231.7	1,281.6	2,485.7	2,480.4
North America [Member] | Land and Development [Member]
Disaggregation Of Revenue [Line Items]
Net sales				18.9
North America [Member] | Intersegment Sales [Member]
Disaggregation Of Revenue [Line Items]
Net sales	(65.3)	(51.4)	(123.2)	(92.9)
South America [Member]
Disaggregation Of Revenue [Line Items]
Net sales	119.6	119.5	222.8	247.1
South America [Member] | Corrugated Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	96.5	100.7	177.5	208.3
South America [Member] | Consumer Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	23.1	18.8	45.3	38.8
Europe [Member]
Disaggregation Of Revenue [Line Items]
Net sales	267	255.9	517.1	502.3
Europe [Member] | Corrugated Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1.1	2.5	2	4.3
Europe [Member] | Consumer Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	265.9	253.4	515.2	498
Europe [Member] | Intersegment Sales [Member]
Disaggregation Of Revenue [Line Items]
Net sales			(0.1)
Asia Pacific [Member]
Disaggregation Of Revenue [Line Items]
Net sales	87.7	76	169.6	160.6
Asia Pacific [Member] | Corrugated Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	18.7	13.6	31.1	24.8
Asia Pacific [Member] | Consumer Packaging [Member]
Disaggregation Of Revenue [Line Items]
Net sales	69.2	62.5	138.8	136
Asia Pacific [Member] | Intersegment Sales [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ (0.2)	$ (0.1)	$ (0.3)	$ (0.2)

Revenue Recognition - Summary o

Revenue Recognition - Summary of Opening and Closing Balances of Contract Assets and Contract Liabilities (Details) $ in Millions	6 Months Ended
	Mar. 31, 2021USD ($)
Disaggregation Of Revenue [Abstract]
Short-Term Contract Assets, Beginning balance	$ 185.8
Increase in Short-Term Contract Assets	5.3
Short-Term Contract Assets, Ending balance	191.1
Short-Term Contract Liabilities, Beginning balance	12
Increase in Short-Term Contract Liabilities	9.9
Short-Term Contract Liabilities, Ending balance	$ 21.9

Restructuring and Other Costs -

Restructuring and Other Costs - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring And Related Activities [Abstract]
Restructuring and other costs	$ 5.2	$ 16.4	$ 12.9	$ 46.5

Restructuring and Other Costs_2

Restructuring and Other Costs - Schedule of Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring And Related Activities [Abstract]
Restructuring	$ 4.1	$ 8	$ 10.7	$ 32.7
Other	1.1	8.4	2.2	13.8
Restructuring and other costs	$ 5.2	$ 16.4	$ 12.9	$ 46.5

Restructuring and Other Costs_3

Restructuring and Other Costs - Schedule of Restructuring Charges Related to Active Restructuring Initiatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 4.1	$ 8	$ 10.7	$ 32.7
Restructuring and Related Cost, Cost Incurred to Date	375.5		375.5
Restructuring and Related Cost, Expected Cost	377.8		377.8
Net Property, Plant and Equipment [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		0.3	0.2	3
Restructuring and Related Cost, Cost Incurred to Date	131.5		131.5
Restructuring and Related Cost, Expected Cost	131.5		131.5
Severance and Other Employee Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	1.3	5.1	5.7	25.6
Restructuring and Related Cost, Cost Incurred to Date	168.7		168.7
Restructuring and Related Cost, Expected Cost	168.7		168.7
Equipment and Inventory Relocation Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		0.9	0.2	1.4
Restructuring and Related Cost, Cost Incurred to Date	12.5		12.5
Restructuring and Related Cost, Expected Cost	13		13
Facility Carrying Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.2	0.4	1	1
Restructuring and Related Cost, Cost Incurred to Date	22.9		22.9
Restructuring and Related Cost, Expected Cost	24.7		24.7
Other Costs Related to Restructuring and Other Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	2.6	1.3	3.6	1.7
Restructuring and Related Cost, Cost Incurred to Date	39.9		39.9
Restructuring and Related Cost, Expected Cost	39.9		39.9
Corporate, Non-Segment [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.7	1.9	2.4	9.6
Restructuring and Related Cost, Cost Incurred to Date	70.8		70.8
Restructuring and Related Cost, Expected Cost	70.8		70.8
Corporate, Non-Segment [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	(0.7)	1.2	0.9	8.9
Restructuring and Related Cost, Cost Incurred to Date	60.3		60.3
Restructuring and Related Cost, Expected Cost	60.3		60.3
Corporate, Non-Segment [Member] | Other Costs Related to Restructuring and Other Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	1.4	0.7	1.5	0.7
Restructuring and Related Cost, Cost Incurred to Date	10.5		10.5
Restructuring and Related Cost, Expected Cost	10.5		10.5
Corrugated Packaging [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.2	(1.7)	0.4	8.8
Restructuring and Related Cost, Cost Incurred to Date	180.3		180.3
Restructuring and Related Cost, Expected Cost	182.3		182.3
Corrugated Packaging [Member] | Net Property, Plant and Equipment [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		0.3		2.5
Restructuring and Related Cost, Cost Incurred to Date	94.4		94.4
Restructuring and Related Cost, Expected Cost	94.4		94.4
Corrugated Packaging [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	(0.4)	(3.5)	(1.1)	3.6
Restructuring and Related Cost, Cost Incurred to Date	51.3		51.3
Restructuring and Related Cost, Expected Cost	51.3		51.3
Corrugated Packaging [Member] | Equipment and Inventory Relocation Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		0.9		1.3
Restructuring and Related Cost, Cost Incurred to Date	8.7		8.7
Restructuring and Related Cost, Expected Cost	9.2		9.2
Corrugated Packaging [Member] | Facility Carrying Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.2	0.4	1	1
Restructuring and Related Cost, Cost Incurred to Date	21.9		21.9
Restructuring and Related Cost, Expected Cost	23.4		23.4
Corrugated Packaging [Member] | Other Costs Related to Restructuring and Other Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.4	0.2	0.5	0.4
Restructuring and Related Cost, Cost Incurred to Date	4		4
Restructuring and Related Cost, Expected Cost	4		4
Consumer Packaging [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	3.2	7.8	7.9	14.3
Restructuring and Related Cost, Cost Incurred to Date	103.8		103.8
Restructuring and Related Cost, Expected Cost	104.1		104.1
Consumer Packaging [Member] | Net Property, Plant and Equipment [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost			0.2	0.5
Restructuring and Related Cost, Cost Incurred to Date	35.3		35.3
Restructuring and Related Cost, Expected Cost	35.3		35.3
Consumer Packaging [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	2.4	7.4	5.9	13.1
Restructuring and Related Cost, Cost Incurred to Date	43.3		43.3
Restructuring and Related Cost, Expected Cost	43.3		43.3
Consumer Packaging [Member] | Equipment and Inventory Relocation Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost			0.2	0.1
Restructuring and Related Cost, Cost Incurred to Date	3.8		3.8
Restructuring and Related Cost, Expected Cost	3.8		3.8
Consumer Packaging [Member] | Facility Carrying Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	1		1
Restructuring and Related Cost, Expected Cost	1.3		1.3
Consumer Packaging [Member] | Other Costs Related to Restructuring and Other Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0.8	$ 0.4	1.6	$ 0.6
Restructuring and Related Cost, Cost Incurred to Date	20.4		20.4
Restructuring and Related Cost, Expected Cost	20.4		20.4
Land and Development [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	20.6		20.6
Restructuring and Related Cost, Expected Cost	20.6		20.6
Land and Development [Member] | Net Property, Plant and Equipment [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	1.8		1.8
Restructuring and Related Cost, Expected Cost	1.8		1.8
Land and Development [Member] | Severance and Other Employee Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	13.8		13.8
Restructuring and Related Cost, Expected Cost	13.8		13.8
Land and Development [Member] | Other Costs Related to Restructuring and Other Costs [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	5		5
Restructuring and Related Cost, Expected Cost	$ 5		$ 5

Restructuring and Other Costs_4

Restructuring and Other Costs - Schedule of Acquisition and Integration Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost And Reserve [Line Items]
Acquisition costs			$ 0.7	$ 0.4
Integration costs			1.3	13.4
Divestiture costs			0.2
Other total	$ 1.1	$ 8.4	2.2	13.8
Other Segments [Member]
Restructuring Cost And Reserve [Line Items]
Acquisition costs	0.5	0.3	0.7	0.4
Integration costs	0.4	8.1	1.3	13.4
Divestiture costs	0.2		0.2
Other total	$ 1.1	$ 8.4	$ 2.2	$ 13.8

Restructuring and Other Costs_5

Restructuring and Other Costs - Schedule of Changes in Restructuring Accrual Charges (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restructuring And Other Costs [Abstract]
Accrual at beginning of fiscal year	$ 17.2	$ 32.3
Additional accruals	8.3	27.5
Payments	(10.4)	(27.3)
Adjustment to accruals	(2.5)	(1.9)
Foreign currency rate changes	0.1
Accrual at March 31	$ 12.7	$ 30.6

Restructuring and Other Costs_6

Restructuring and Other Costs - Schedule of Reconciliation of Accruals and Charges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring And Other Costs [Abstract]
Additional accruals and adjustments to accruals (see table above)			$ 5.8	$ 25.6
Acquisition costs			0.7	0.4
Integration costs			1.3	13.4
Divestiture costs			0.2
Net property, plant and equipment costs			0.2	3
Severance and other employee costs			0.1	(0.3)
Equipment and inventory relocation costs			0.2	1.4
Facility carrying costs			1	1
Other costs			3.4	2
Restructuring and other costs	$ 5.2	$ 16.4	$ 12.9	$ 46.5

Retirement Plans - Additional I

Retirement Plans - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Multiemployer Plans, Withdrawal Obligation	$ 243.2		$ 243.2		$ 252
Pace Industry Union Management Pension Fund [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Withdrawal obligation, per month			$ 0.7
Periods of Payments Used to Calculate Withdrawal Liability in Connection with PIUMPF Withdrawal			20 years
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by employer to pension and supplemental retirement plans	5.2	$ 4.1	$ 10.8	$ 12.6
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by employer to pension and supplemental retirement plans	$ 1.8	$ 1.7	$ 3.1	$ 3.7

Retirement Plans - Summary of C

Retirement Plans - Summary of Components of Net Pension Income and Summary of Components of Postretirement Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 13.6	$ 14.2	$ 27.1	$ 27.3
Interest cost	46.7	49.5	93.1	99.4
Expected return on plan assets	(92.3)	(90.8)	(184)	(181.6)
Amortization of net actuarial loss (gain)	8	11.8	15.9	23.7
Amortization of prior service cost (credit)	2	2.1	4	3.5
Curtailment loss		0.4		0.4
Company defined benefit plan income	(22)	(12.8)	(43.9)	(27.3)
Multiemployer and other plans	0.4	0.4	0.8	0.7
Net pension (income) cost	(21.6)	(12.4)	(43.1)	(26.6)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.3	0.3	0.6	0.7
Interest cost	1.5	1.8	2.9	3.6
Amortization of net actuarial loss (gain)	(0.3)	(0.2)	(0.6)	(0.4)
Amortization of prior service cost (credit)	(0.6)	(0.7)	(1.2)	(1.4)
Net pension (income) cost	$ 0.9	$ 1.2	$ 1.7	$ 2.5

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rates	21.00%	28.00%	23.20%	26.60%

Segment Information - Additiona

Segment Information - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Mar. 31, 2021USD ($)segment	Mar. 31, 2020USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Insurance proceeds received, net cash used for investing activities			$ 1.7	$ 1.4
Corrugated Packaging [Member] | Hurricane Michael [Member]
Segment Reporting Information [Line Items]
Insurance proceeds received		$ 32.3
Deferred insurance proceeds		2.8
Deferred insurance proceeds recognized in cost of goods sold	$ 2.8
Insurance proceeds from business interruption recoveries		11.7
Insurance proceeds for direct costs and property damage		20.6
Insurance proceeds received, net cash provided by operating activities				30.9
Insurance proceeds received, net cash used for investing activities				$ 1.4
Corrugated Packaging [Member] | Hurricane Michael [Member] | Cost of Goods Sold [Member]
Segment Reporting Information [Line Items]
Reduction of cost of goods sold		$ 29.5

Segment Information - Certain O

Segment Information - Certain Operating Data for Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net sales	$ 4,437.8	$ 4,447.3	$ 8,839.3	$ 8,871
Gain on sale of certain closed facilities		5	0.9	5.5
Multiemployer pension withdrawal expense		(0.9)		(0.9)
Restructuring and other costs	(5.2)	(16.4)	(12.9)	(46.5)
Interest expense, net	(83.5)	(97.3)	(177.3)	(190.8)
Loss on extinguishment of debt		(0.5)	(1.1)	(0.5)
Other (expense) income, net	(13.4)	(0.9)	7.4	(4.6)
Income before income taxes	144.9	206.7	347.7	392.7
Depreciation, depletion and amortization	361.4	374.5	725.9	755.7
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	4,503.3	4,498.8	8,962.9	8,964.1
Segment income	286.5	335.3	594	666.3
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(65.5)	(51.5)	(123.6)	(93.1)
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Non-allocated expenses	(39.5)	(17.6)	(63.3)	(35.8)
Interest expense, net	(83.5)	(97.3)	(177.3)	(190.8)
Corrugated Packaging [Member]
Segment Reporting Information [Line Items]
Net sales	2,913.4	2,882.5	5,777.9	5,792
Depreciation, depletion and amortization	229.9	239.6	462.2	483.9
Corrugated Packaging [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	2,913.4	2,882.5	5,777.9	5,792
Segment income	205.3	244.5	420.3	527.9
Corrugated Packaging [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(18.6)	(20.7)	(40.6)	(39)
Corrugated Packaging [Member] | Unaffiliated Customers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	2,894.8	2,861.8	5,737.3	5,753
Consumer Packaging [Member]
Segment Reporting Information [Line Items]
Net sales	1,589.9	1,616.3	3,185	3,153.2
Depreciation, depletion and amortization	130.1	133.2	261.1	268.5
Consumer Packaging [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	1,589.9	1,616.3	3,185	3,153.2
Segment income	81.2	90.8	173.7	137
Consumer Packaging [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(46.9)	(30.8)	(83)	(54.1)
Consumer Packaging [Member] | Unaffiliated Customers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	1,543	1,585.5	3,102	3,099.1
Land and Development [Member]
Segment Reporting Information [Line Items]
Net sales				18.9
Land and Development [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales				18.9
Segment income				1.4
Land and Development [Member] | Unaffiliated Customers [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales				18.9
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	$ 1.4	$ 1.7	$ 2.6	$ 3.3

Interest Expense, Net - Summary

Interest Expense, Net - Summary of Components of Interest Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Interest Income Expense Net [Abstract]
Interest expense	$ (94.9)	$ (112.1)	$ (200.4)	$ (231.3)
Interest income	11.4	14.8	23.1	40.5
Interest expense, net	$ (83.5)	$ (97.3)	$ (177.3)	$ (190.8)

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Inventories [Abstract]
Finished goods and work in process	$ 917.8	$ 844.2
Raw materials	784.4	772.7
Spare parts and supplies	517.9	500.3
Inventories at FIFO cost	2,220.1	2,117.2
LIFO reserve	(129.2)	(93.8)
Net inventories	$ 2,090.9	$ 2,023.4

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Property, plant and equipment at cost:
Property, plant and equipment, at cost	$ 18,226	$ 17,915.5
Less: accumulated depreciation, depletion and amortization	(7,653.5)	(7,136.6)
Property, plant and equipment, net	10,572.5	10,778.9
Land and Buildings [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	2,546.6	2,524.7
Machinery and Equipment [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	15,432.9	15,147.3
Forestlands and Mineral Rights [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	112.6	110.8
Transportation Equipment [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	28	29.1
Leasehold Improvements [Member]
Property, plant and equipment at cost:
Property, plant and equipment, at cost	$ 105.9	$ 103.6

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 04, 2020	Sep. 30, 2020	Sep. 17, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maximum eligible receivables that may be sold					$ 88.5		$ 700
Receivables sold under accounts receivable sales agreement	$ 621.1		$ 621.1			$ 589.4
Estimated loss on sale of accounts receivable by quarter	2.7	$ 4.1	5.7	$ 8.4
Grupo Gondi [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Charge on not exercising option to purchase additional equity interest in joint venture	$ 22.5		$ 22.5

Fair Value - Summary of Account

Fair Value - Summary of Accounts Receivable Sales Agreement (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Receivables sold to the financial institution and derecognized	$ (1,302.8)	$ (1,210.2)
Receivables collected by financial institution	1,271	1,219.6
Cash proceeds from (paid to) financial institution	$ 31.8	$ (9.4)

Debt - Schedule of Carrying Val

Debt - Schedule of Carrying Value of Individual Components of Debt (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Total debt	$ 8,942.6	$ 9,430.6
Less: current portion of debt	549.5	222.9
Long-term debt due after one year	8,393.1	9,207.7
Notes Due Fiscal 2022 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	399.6	399.3
Notes Due Fiscal 2023 to 2028 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	3,775.9	3,773.6
Notes Due Fiscal 2029 to 2033 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	2,772.7	2,778.9
Notes Due Fiscal 2037 to 2047 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	178.4	178.6
Term Loan Facilities [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	848.8	1,547.6
Revolving Credit and Swing Facilities [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	370	250
Finance Lease Obligations [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Total debt	269.3	274.8
Vendor Financing and Commercial Card Programs [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total debt	96.8	89.8
International and Other Debt [Member]
Debt Instrument [Line Items]
Total debt	$ 231.1	$ 138

Debt - Additional Information (

Debt - Additional Information (Details)	Mar. 12, 2021USD ($)	Feb. 26, 2021EUR (€)	Jan. 18, 2021BRL (R$)	Nov. 21, 2019USD ($)	Sep. 27, 2019USD ($)	Jun. 07, 2019USD ($)	Dec. 07, 2018USD ($)	Mar. 31, 2021USD ($)	Sep. 30, 2020USD ($)	Mar. 31, 2021BRL (R$)	Jul. 01, 2015USD ($)
Debt Instrument [Line Items]
Fair value of debt								$ 9,700,000,000	$ 10,400,000,000
Revolving Credit Facility [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit Facility, maximum borrowing capacity				$ 2,300,000,000							$ 2,000,000,000
Credit facility, maturity date				Nov. 21, 2024
Long-term debt								0	0
Wells Fargo Bank NA Credit Facility [Member] | Terminated Unsecured Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term debt									$ 648,900,000
Debt instrument, maturity period									5 years
Bank of America Five Year Term Loan [Member] | Unsecured [Member]
Debt Instrument [Line Items]
Credit Facility, maximum borrowing capacity						$ 300,000,000
Credit facility, maturity date						Jun. 7, 2024
Long-term debt								$ 250,000,000	$ 300,000,000
Debt instrument, maturity period						5 years
Debt instrument, interest rate description								The applicable interest rate margins are 0.825% to 1.750% per annum for LIBOR rate loans and 0.000% to 0.750% per annum for alternate base rate loans, in each case depending on the Leverage Ratio (as defined in the credit agreement) or our corporate credit ratings, whichever yields a lower applicable interest rate margin, at such time.
Farm Credit Facility [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit Facility, maximum borrowing capacity					$ 600,000,000
Long-term debt								$ 598,800,000	598,700,000
Debt Instrument, Term, in Years					7 years
Receivables Securitization Facility [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term debt								0	0
Receivables backed financing, maximum borrowing amount	$ 700,000,000
Debt instrument, amended maturity date	Mar. 11, 2024
Debt instrument, maximum borrowing capacity, amount								592,100,000	700,000,000
Loans and Leases Receivable, Collateral for Secured Borrowings								898,500,000	1,128,300,000
Receivables Securitization Facility [Member] | Secured Debt [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Variable rate basis	a blend of the market rate for asset-backed commercial paper and the one-month LIBOR rate plus a credit spread
Cooperatieve Rabobank U.A., New York Branch European Revolving Credit Facility [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit Facility, maximum borrowing capacity | €		€ 600,000,000
Credit facility, maturity date		Feb. 26, 2024
Long-term debt								370,000,000	250,000,000
Debt instrument, maturity period		3 years
Incremental line of credit | €		€ 100,000,000
Line of credit facility, maximum Euro denominated borrowing capacity | €		€ 600,000,000
Cooperatieve Rabobank U.A., New York Branch European Revolving Credit Facility [Member] | Unsecured Debt [Member] | Foreign Exchange Contract [Member]
Debt Instrument [Line Items]
Amount of foreign exchange contracts								370,300,000
Commercial Paper [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term debt								0	$ 0
Aggregate Principal Amount of Short-term Unsecured Commercial Paper Program, Maximum							$ 1,000,000,000
Debt Instrument, notice period for termination							30 days
Brazil Export Credit Note [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit Facility, maximum borrowing capacity | R$			R$ 500000000.0
Credit facility, maturity date			Jan. 19, 2026
Long-term debt								$ 86,700,000		R$ 500000000.0
Credit facility semiannual installments repayment beginning date			Jan. 19, 2023
Credit facility basis spread on floating rate			2.50%
Maximum [Member] | Revolving Credit Facility [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit facility, maximum permitted debt to capitalization ratio				0.65
Maximum [Member] | Bank of America Five Year Term Loan [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin						1.75%
Maximum [Member] | Bank of America Five Year Term Loan [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin						0.75%
Maximum [Member] | Farm Credit Facility [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Credit facility, amount of potential increase to the principal amount					$ 300,000,000
Maximum [Member] | Commercial Paper [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt instrument, maturity period							397 days
Minimum [Member] | Bank of America Five Year Term Loan [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Applicable margin						0.825%
Minimum [Member] | Bank of America Five Year Term Loan [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Applicable margin						0.00%

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Total lease cost, net	$ 79.2	$ 81.1	$ 160.1	$ 160.1
ROU asset obtained in exchange for operating lease liability			$ 98.4	$ 58.7

Leases - Summary of Supplementa

Leases - Summary of Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020
Supplementary Information Balance Sheets [Abstract]
Operating lease right-of-use asset	$ 696.4	$ 658.6
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Operating lease right-of-use asset	Operating lease right-of-use asset
Current operating lease liabilities	$ 181.9	$ 172.7
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current operating lease liabilities	Current operating lease liabilities
Operating lease liabilities	$ 573.2	$ 545.8
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Operating lease liabilities	Operating lease liabilities
Total operating lease liabilities	$ 755.1	$ 718.5
Property, plant and equipment	143	143.2
Accumulated depreciation	(23.7)	(19.1)
Property, plant and equipment, net	119.3	124.1
Current finance lease liabilities	$ 8.8	$ 9
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current finance lease liabilities	Current finance lease liabilities
Noncurrent finance lease liabilities	$ 260.5	$ 265.8
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Noncurrent finance lease liabilities	Noncurrent finance lease liabilities
Total finance lease liabilities	$ 269.3	$ 274.8

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) R$ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2021USD ($)lawsuit	Mar. 31, 2021USD ($)lawsuitSubsidiary	Mar. 31, 2021BRL (R$)Subsidiary	Mar. 31, 2020USD ($)
Commitments and Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 4,900,000	$ 4,900,000
Guarantor Obligations, Estimated Exposure, Undiscounted	50,000,000	50,000,000
Guarantor Obligations, Current Carrying Value	9,600,000	9,600,000
Indirect tax claim - reduction of cost of goods sold	400,000	600,000		$ 23,500,000
Indirect tax claim - reduction of interest expense, net	900,000	300,000		$ 11,600,000
Brazil Administrative Council of Tax Appeals [Member]
Commitments and Contingencies [Line Items]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense		$ 121,000,000	R$ 696
Tax claim and conversion description		The matter has proceeded through the Brazil Administrative Council of Tax Appeals (“CARF”) principally in two proceedings, covering tax years 2003 to 2008 and 2009 to 2012.	The matter has proceeded through the Brazil Administrative Council of Tax Appeals (“CARF”) principally in two proceedings, covering tax years 2003 to 2008 and 2009 to 2012.
Income tax settlement claim liability	$ 0	$ 0
Tax claim and conversion, tax dispute related to tax years description		2003 to 2008	2003 to 2008
Tax claim and conversion, tax penalties relating to tax years description		2009 to 2012	2009 to 2012
Tax claim and conversion proceedings covering tax years description		2003 to 2008 and 2009 to 2012	2003 to 2008 and 2009 to 2012
Brazil [Member]
Commitments and Contingencies [Line Items]
Number of subsidiaries | Subsidiary		2	2
Asbestos Litigation [Member]
Commitments and Contingencies [Line Items]
Number of Lawsuits the Company Has Been Named a Defendant in Asbestos-related Personal Injury Litigation | lawsuit	1,400	1,400
Estimated liability for litigation	$ 13,800,000	$ 13,800,000
Other Long Term Liabilities [Member]
Commitments and Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	1,700,000	1,700,000
Other Current Liabilities [Member]
Commitments and Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 3,200,000	$ 3,200,000

Equity and Other Comprehensiv_3

Equity and Other Comprehensive Income (Loss) - Additional Information (Details) - $ / shares shares in Millions	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020	Jul. 01, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Stock repurchase program, number of shares authorized to be repurchased				40
Common Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01	$ 0.01
Authorized share repurchase as a percentage of common stock outstanding				15.00%
Stock repurchase program, remaining number of shares authorized to be repurchased	19.1
Treasury stock, shares, acquired	0	0
Minimum [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Effective Tax Rate, Net of Tax Components of Other Comprehensive Income	24.00%	26.00%
Maximum [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Effective Tax Rate, Net of Tax Components of Other Comprehensive Income	25.00%	27.00%

Equity and Other Comprehensiv_4

Equity and Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions		6 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	[1]	$ (1,319.9)	$ (1,069.2)
Other comprehensive (loss) income before reclassifications	[1]	109.4	(296)
Amounts reclassified from accumulated other comprehensive loss	[1]	16.2	19.6
Net current period other comprehensive (loss) income	[1]	125.6	(276.4)
Reclassification of stranded tax effects	[1]		(73.4)
Balance at end of period	[1]	(1,194.3)	(1,419)
Accumulated Net Gain (Loss) from Designated or Quality Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(5.6)	0.7
Other comprehensive (loss) income before reclassifications		(0.1)	(9.4)
Amounts reclassified from accumulated other comprehensive loss		2.9	1.1
Net current period other comprehensive (loss) income		2.8	(8.3)
Balance at end of period		(2.8)	(7.6)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(727.7)	(698)
Amounts reclassified from accumulated other comprehensive loss		13.3	18.5
Net current period other comprehensive (loss) income		13.3	18.5
Reclassification of stranded tax effects			(73.4)
Balance at end of period		(714.4)	(752.9)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period		(586.6)	(371.9)
Other comprehensive (loss) income before reclassifications		109.5	(286.6)
Net current period other comprehensive (loss) income		109.5	(286.6)
Balance at end of period		$ (477.1)	$ (658.5)
[1]	All amounts are net of tax and noncontrolling interests.

Equity and Other Comprehensiv_5

Equity and Other Comprehensive Income (Loss) - Summary of Reclassification out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization and settlement recognition of net actuarial loss, included in pension cost		$ 5.8	$ 8.5	$ 11.4	$ 17.2
Amortization of prior service costs, Net of Tax		1	1	2.1	1.5
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax		1.4	2.5	2.9	1.2
Reclassification of stranded tax effects	[1]				73.4
Parent [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of net actuarial loss, Pre-Tax Amount	[2],[3]	(7.4)	(11.5)	(14.8)	(23.1)
Amortization of net actuarial loss, Tax	[2],[3]	1.7	3.1	3.6	6.1
Amortization and settlement recognition of net actuarial loss, included in pension cost	[2],[3]	(5.7)	(8.4)	(11.2)	(17)
Amortization of prior service costs, Pre-Tax Amount	[2],[3]	(1.3)	(1.3)	(2.8)	(2)
Amortization of prior service costs, Tax	[2],[3]	0.3	0.3	0.7	0.5
Amortization of prior service costs, Net of Tax	[2],[3]	(1)	(1)	(2.1)	(1.5)
Defined Benefit Plans, before Tax	[2]	(8.7)	(12.8)	(17.6)	(25.1)
Defined Benefit Plans, Tax	[2]	2	3.4	4.3	80
Defined Benefit Plans, Net of Tax	[2]	(6.7)	(9.4)	(13.3)	54.9
Total Reclassifications From Other Comprehensive Income Before Tax	[2]	(10.6)	(16.2)	(21.5)	(26.7)
Total Reclassifications From Other Comprehensive Income Tax Portion	[2]	2.5	4.4	5.3	80.5
Total Reclassifications From Other Comprehensive Income Net of Tax	[2]	(8.1)	(11.8)	(16.2)	53.8
Parent [Member] | ASU 2018-02 [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification of stranded tax effects	[4]				73.4
Reclassification of stranded tax effects net	[4]				73.4
Parent [Member] | Cash Flow Hedges [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[2]	(1.9)	(3.4)	(3.9)	(1.6)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	[2]	0.5	1	1	0.5
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	[2]	(1.4)	(2.4)	(2.9)	(1.1)
Parent [Member] | Interest Rate Contract [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[2],[5]	(1.9)	0.3	(3.9)	1
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	[2],[5]	0.5		1	(0.2)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	[2],[5]	$ (1.4)	0.3	$ (2.9)	0.8
Parent [Member] | Natural Gas Commodity Hedge [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	[2],[6]		(3.7)		(2.6)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	[2],[6]		1		0.7
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	[2],[6]		$ (2.7)		$ (1.9)
[1]	All amounts are net of tax and noncontrolling interests.
[2]	Amounts in parentheses indicate charges to earnings. Amounts pertaining to noncontrolling interests are excluded.
[3]	Included in the computation of net periodic pension cost. See “ Note 4. Retirement Plans
[4]	Amount reclassified to retained earnings as a result of the adoption of ASU 2018-02 .
[5]	These accumulated other comprehensive income components are included in Interest expense, net.
[6]	These accumulated other comprehensive income components are included in Cost of goods sold.

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 112.5	$ 148.1	$ 264.5	$ 286.6
Less: Distributed and undistributed income available to participating securities, Basic	(0.1)	(0.1)	(0.1)	(0.1)
Distributed and undistributed income available to common stockholders, Basic	112.4	148	264.4	286.5
Less: Distributed and undistributed income available to participating securities, Diluted	(0.1)	(0.1)	(0.1)	(0.1)
Distributed and undistributed income available to common stockholders, Diluted	$ 112.4	$ 148	$ 264.4	$ 286.5
Basic weighted average shares outstanding	264.9	259	263.8	258.6
Effect of dilutive stock options and non- participating securities	2.1	1.2	2.1	1.5
Diluted weighted average shares outstanding	267	260.2	265.9	260.1
Basic earnings per share attributable to common stockholders	$ 0.42	$ 0.57	$ 1	$ 1.11
Diluted earnings per share attributable to common stockholders	$ 0.42	$ 0.57	$ 0.99	$ 1.10

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.6	1.8	0.6	1.4