Post (POST) 10-K 20 Nov 20 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Sep. 30, 2020	Nov. 16, 2020	Mar. 31, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	1-35305
Entity Registrant Name	POST HOLDINGS, INC.
Entity Incorporation, State or Country Code	MO
Entity Tax Identification Number	45-3355106
Entity Address, Address Line One	2503 S. Hanley Road
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63144
City Area Code	314
Local Phone Number	644-7600
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	POST
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 4,680,868,433
Entity Common Stock, Shares Outstanding (in shares)		65,848,095
Documents Incorporated by Reference	Certain portions of the registrant’s definitive proxy statement for its 2021 annual meeting of shareholders, to be filed with the Securities and Exchange Commission within 120 days after September 30, 2020, are incorporated by reference into Part III of this report.
Entity Central Index Key	0001530950
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net Sales	$ 5,698.7	$ 5,681.1	$ 6,257.2
Cost of goods sold	3,911.3	3,889	4,403.2
Gross Profit	1,787.4	1,792.1	1,854
Selling, general and administrative expenses	934.3	911.6	976.4
Amortization of intangible assets	160.3	161.3	177.4
Gain on sale of business	0	(126.6)	0
Impairment of goodwill and other intangible assets	0	63.3	124.9
Other operating (income) expenses, net	(7.7)	1.5	1.8
Operating Profit	700.5	781	573.5
Interest expense, net	388.6	322.4	387.3
Loss on extinguishment of debt, net	72.9	6.1	31.1
Expense (income) on swaps, net	187.1	306.6	(95.6)
Other income, net	(11.5)	(13.2)	(14)
Earnings before Income Taxes and Equity Method Loss	63.4	159.1	264.7
Income tax expense (benefit)	3.5	(3.9)	(204)
Equity method loss, net of tax	30.9	37	0.3
Net Earnings Including Noncontrolling Interests	29	126	468.4
Less: Net earnings attributable to noncontrolling interests	28.2	1.3	1.1
Net Earnings	0.8	124.7	467.3
Less: Preferred stock dividends	0	3	10
Net Earnings Available to Common Shareholders	$ 0.8	$ 121.7	$ 457.3
Earnings per share:
Basic earnings per common share (in usd per share)	$ 0.01	$ 1.72	$ 6.87
Diluted earnings per common share (in usd per share)	$ 0.01	$ 1.66	$ 6.16
Weighted-Average Common Shares Outstanding:
Weighted-average shares for basic earnings per share	68.9	70.8	66.6
Weighted-average shares for diluted earnings per share	70.1	75.1	75.9

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net earnings including noncontrolling interests	$ 29	$ 126	$ 468.4
Pension and postretirement benefits adjustments:
Unrealized pension and postretirement benefit obligations	(36.8)	(12.5)	5
Reclassifications to net earnings	(2.2)	(3.1)	(3.2)
Tax benefit (expense) on hedging adjustments:
Net gain on derivatives	22.5	40.5	72.2
Reclassifications to net earnings	8.2	(31)	(3.6)
Other reclassifications	0	0	(0.5)
Foreign currency translation adjustments:
Unrealized foreign currency translation adjustments	72.3	(95.3)	(50.7)
Reclassifications to net earnings (see Note 6)	0	42.1	0
Tax benefit (expense) on pension and postretirement benefits adjustments:
Unrealized pension and postretirement benefit obligations	(7.5)	(3.4)	0.8
Reclassification to net earnings	0.6	0.9	0.8
Adoption of accounting standards updates	0	0	1
Tax benefit (expense) on hedging adjustments:
Net gain on derivatives	(5.4)	(10.1)	(18.1)
Reclassification to net earnings	(1.9)	7.7	0.9
Adoption of accounting standards updates	0	0	(2.4)
Total Other Comprehensive Income (Loss) Including Noncontrolling Interests	64.8	(57.4)	0.6
Less: Comprehensive income attributable to noncontrolling interests	25.5	1.3	1.1
Total Comprehensive Income	$ 68.3	$ 67.3	$ 467.9

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Current Assets
Cash and cash equivalents	$ 1,187.9	$ 1,050.7
Restricted cash	5.5	3.8
Receivables, net	441.6	445.1
Inventories	599.4	579.8
Prepaid expenses and other current assets	53.4	46.9
Total Current Assets	2,287.8	2,126.3
Property, net	1,779.7	1,736
Goodwill	4,438.6	4,399.8
Other intangible assets, net	3,197.5	3,338.5
Equity method investments	114.1	145.5
Other assets	329	205.5
Total Assets	12,146.7	11,951.6
Current Liabilities
Current portion of long-term debt	64.9	13.5
Accounts payable	367.9	395.6
Other current liabilities	541.6	393.8
Total Current Liabilities	974.4	802.9
Long-term debt	6,959	7,066
Deferred income taxes	784.5	688.5
Other liabilities	599.8	456.9
Total Liabilities	9,317.7	9,014.3
Commitments and Contingencies
Shareholders’ Equity
Preferred stock, $0.01 par value, 50.0 shares authorized, zero shares issued and outstanding in each year	0	0
Common stock, $0.01 par value, 300.0 shares authorized, 66.4 and 72.1 shares outstanding, respectively	0.8	0.8
Additional paid-in capital	4,182.9	3,734.8
Retained earnings	208.6	207.8
Accumulated other comprehensive loss	(29.3)	(96.8)
Treasury stock, at cost, 18.0 and 11.9 shares, respectively	(1,508.5)	(920.7)
Total Shareholders’ Equity Excluding Noncontrolling Interests	2,854.5	2,925.9
Noncontrolling interests	(25.5)	11.4
Total Shareholders’ Equity	2,829	2,937.3
Total Liabilities and Shareholders’ Equity	$ 12,146.7	$ 11,951.6

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheet (Parentheticals) - $ / shares shares in Millions	Sep. 30, 2020	Sep. 30, 2019
Preferred Stock
Par value of preferred stock	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	50	50
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock
Par value of common stock	$ 0.01	$ 0.01
Common Stock, Shares Authorized	300	300
Common Stock, Shares, Issued	66.4	72.1
Treasury Stock
Treasury Stock, Shares	18	11.9

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities:
Net earnings including noncontrolling interests	$ 29	$ 126	$ 468.4
Adjustments to reconcile net earnings including noncontrolling interest to net cash provided by operating activities:
Depreciation and amortization	370.3	379.6	398.4
Gain on sale of business	0	(126.6)	0
Loss on extinguishment of debt, net	72.9	6.1	31.1
Impairment of goodwill and other intangible assets	0	63.3	124.9
Unrealized loss (gain) on interest rate swaps and foreign exchange contracts, net	125.5	293.1	(96.7)
Non-cash stock-based compensation expense	49.7	38.9	30.9
Equity method loss, net of tax	30.9	37	0.3
Deferred income taxes	(43.6)	(80.3)	(256.5)
Other, net	1.4	8.7	9.2
Other changes in operating assets and liabilities, net of business acquisitions and held for sale assets and liabilities:
Decrease (increase) in receivables	20.3	19.3	(6)
(Increase) decrease in inventories	(4.6)	(97.9)	3.6
(Increase) decrease in prepaid expenses and other current assets	(27.3)	20.7	7.2
Decrease (increase) in other assets	5	0.2	(24)
(Decrease) increase in accounts payable and other current liabilities	(26.8)	4.4	29.4
Increase (decrease) in non-current liabilities	22.9	(4.5)	(1.6)
Net Cash Provided by Operating Activities	625.6	688	718.6
Cash Flows from Investing Activities
Business acquisitions, net of cash acquired	(19.9)	0	(1,454.4)
Additions to property	(234.6)	(273.9)	(225)
Proceeds from sale of businesses	0	266.8	0
Cross-currency swap cash settlements	52.7	31.7	4.8
Purchases of equity securities	(29.2)	0	0
Insurance proceeds on property losses	10	0	0
Other, net	2.5	2.1	(1)
Net Cash (Used in) Provided by Investing Activities	(218.5)	26.7	(1,675.6)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	4,258.2	750	1,625
Repayments of long-term debt	(4,349.1)	(919.1)	(912.1)
Payments to appraisal rights holders	(3.8)	(253.6)	0
Purchases of treasury stock	(589.1)	(322.1)	(218.7)
Payments of preferred stock dividends	0	(4)	(10.8)
Proceeds from initial public offering	524.4	0	0
Premium from issuance of long-term debt	22	0	0
Payments of debt issuance costs, financing fees and modification costs	(45.3)	(16.3)	(24.9)
Refund of debt issuance costs	15.3	7.8	0
Payments of debt extinguishment costs	(49.8)	0	(33.7)
Proceeds from exercise of stock awards	3.9	112.6	5.7
Cash paid for share repurchase contracts	46.4	0	0
Distribution to noncontrolling interest	0	0	(1.4)
Other, net	(12.3)	(7.7)	(5.7)
Net Cash (Used in) Provided by Financing Activities	(272)	(652.4)	423.4
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	3.8	(2.3)	(2)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	138.9	60	(535.6)
Cash, Cash Equivalents and Restricted Cash, Beginning of Year	1,054.5	994.5	1,530.1
Cash, Cash Equivalents and Restricted Cash, End of Year	$ 1,193.4	$ 1,054.5	$ 994.5

Consolidated Statement of Share

Consolidated Statement of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retirement Benefit Adjustments, net of tax	Hedging Adjustments, net of tax	Foreign Currency Translation Adjustments	Treasury Stock	Noncontrolling Interest	Common Stock	Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares												4.7
Common Stock, Shares											66.1
Balance at beginning of period at Sep. 30, 2017	$ 2,789.7	$ 0	$ 0.7	$ 3,566.5	$ (376)	$ 35.1	$ (11.1)	$ (64)	$ (371.2)	$ 9.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	467.3				467.3
Adoption of accounting standards updates	1.4				1.4
Preferred stock dividends declared	(10.8)			(6.8)	(4)
Preferred stock conversion (shares)												(1.5)
Preferred Stock Conversion, Shares Issued											3.1
Preferred Stock Conversion	0.1		0.1
Activity under stock and deferred compensation plans	0.3			0.3
Activity under stock and deferred compensation plans (shares)											0.3	0
Non-cash stock-based compensation expense	30.9			30.9
Purchases of treasury stock (shares)											(2.8)
Purchases of treasury stock	(218.7)			0					(218.7)		$ (218.7)
Net earnings attributable to noncontrolling interest	1.1									1.1
Distribution to noncontrolling interest	(1.4)				(0.7)					(0.7)
Other comprehensive income (loss):
Net change in retirement benefits, net of tax	2.8					2.8
Net change in hedges, net of tax	48.5						48.5
Foreign currency translation adjustments	(50.7)							(50.7)
Balance at the end of period at Sep. 30, 2018	3,060.5	0	0.8	3,590.9	88	37.9	37.4	(114.7)	(589.9)	10.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares												3.2
Common Stock, Shares											66.7
Net earnings	124.7				124.7
Adoption of accounting standards updates	(0.9)				(0.9)
Preferred stock dividends declared	(4)			0	(4)
Preferred stock conversion (shares)												(3.2)
Preferred stock conversion		0
Preferred Stock Conversion, Shares Issued											5.9
Preferred Stock Conversion			0
Preferred stock conversion	(0.1)			(0.1)
Activity under stock and deferred compensation plans	105.1			105.1
Activity under stock and deferred compensation plans (shares)											2.8	0
Non-cash stock-based compensation expense	38.9			38.9
Purchases of treasury stock (shares)											(3.3)
Purchases of treasury stock	(330.8)			0					(330.8)		$ (330.8)
Net earnings attributable to noncontrolling interest	1.3									1.3
Distribution to noncontrolling interest	0
Other comprehensive income (loss):
Net change in retirement benefits, net of tax	(11.3)					(11.3)
Net change in hedges, net of tax	7.1						7.1
Foreign currency translation adjustments	(53.2)							(53.2)
Balance at the end of period at Sep. 30, 2019	2,937.3	0	0.8	3,734.8	207.8	26.6	44.5	(167.9)	(920.7)	11.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares												0
Common Stock, Shares											72.1
Net earnings	0.8				0.8
Activity under stock and deferred compensation plans	(8.2)			(8.3)						0.1
Activity under stock and deferred compensation plans (shares)											0.4	0
Non-cash stock-based compensation expense	49.7			47.2						2.5
Purchases of treasury stock (shares)											(6.1)	0
Purchases of treasury stock	(587.8)								(587.8)		$ (587.8)
Initial public offering	390.6			455.6						(65)
Net earnings attributable to noncontrolling interest	28.2									28.2
Cash paid for share repurchase contracts	(46.4)			(46.4)
Distribution to noncontrolling interest	0
Other comprehensive income (loss):
Net change in retirement benefits, net of tax	(30.9)					(30.9)
Net change in hedges, net of tax	23.4						25.8			(2.4)
Foreign currency translation adjustments	72.3							72.6		(0.3)
Balance at the end of period at Sep. 30, 2020	$ 2,829	$ 0	$ 0.8	$ 4,182.9	$ 208.6	$ (4.3)	$ 70.3	$ (95.3)	$ (1,508.5)	$ (25.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares												0
Common Stock, Shares											66.4

Background

Background	12 Months Ended
	Sep. 30, 2020
Background [Abstract]
Background	BACKGROUND Post Holdings, Inc. (“Post” or the “Company”) is a consumer packaged goods holding company operating in the center-of-the-store, refrigerated, foodservice, food ingredient and convenient nutrition food categories. The Company also participates in the private brand food category, including through its investment with third parties in 8th Avenue Food & Provisions, Inc. (“8th Avenue”). The Company’s products are sold through a variety of channels, including grocery, club and drug stores, mass merchandisers, foodservice, food ingredient and eCommerce. As of September 30, 2020, Post operates in five reportable segments: Post Consumer Brands, Weetabix, Foodservice, Refrigerated Retail and BellRing Brands. The Post Consumer Brands segment includes the North American ready-to-eat (“RTE”) cereal business; the Weetabix segment includes primarily the United Kingdom (the “U.K.”) RTE cereal and muesli business; the Foodservice segment includes primarily egg and potato products; the Refrigerated Retail segment includes side dishes and egg, cheese and sausage products; and the BellRing Brands segment includes ready-to-drink (“RTD”) protein shakes and other RTD beverages, powders and nutrition bars. On October 21, 2019, BellRing Brands, Inc. (“BellRing”), a subsidiary of the Company, closed its initial public offering (the “IPO”) of 39.4 shares of its Class A common stock, $0.01 par value per share (the “Class A Common Stock”). The IPO was completed at an offering price of $14.00 per share and BellRing received net proceeds from the IPO of $524.4, after deducting underwriting discounts and commissions. As a result of the IPO and certain other transactions completed in connection with the IPO (the “formation transactions”), BellRing is a publicly-traded company whose Class A Common Stock is traded on the New York Stock Exchange under the ticker symbol “BRBR”. BellRing is a holding company of BellRing Brands, LLC, a Delaware limited liability company (“BellRing LLC”), owning 28.8% of its non-voting membership units (the “BellRing LLC units”). Post owns 71.2% of the BellRing LLC units and one share of BellRing’s Class B common stock, $0.01 par value per share (the “Class B Common Stock” and, collectively with the Class A Common Stock, the “BellRing Common Stock”). The Class B Common Stock has voting rights but no rights to dividends or other economic rights. For so long as Post or its affiliates (other than BellRing and its subsidiaries) directly own more than 50% of the BellRing LLC units, the Class B Common Stock represents 67% of the combined voting power of the BellRing Common Stock. BellRing LLC is the holding company for Post’s historical active nutrition business, reported herein as the BellRing Brands segment and reported historically as the Active Nutrition segment. In connection with the IPO, the Company incurred transaction-related expenses of $2.5 and $6.7 du ring the years ended September 30, 2020 and 2019, respectively. These expenses generally included third party costs for due diligence, advisory services and government filing fees and were recorded as “Selling, general and administrative expenses” in the Consolidated Statements of Operations. The Company did not incur transaction-related expenses in connection with the IPO during the year ended September 30, 2018. Effective October 21, 2019, the financial results of BellRing and its subsidiaries were consolidated within Post’s financial results and 28.8% of the consolidated net income and net assets of BellRing and its subsidiaries, representing the percentage of economic interest in BellRing LLC held by BellRing (and therefore indirectly held by the public stockholders of BellRing through their ownership of the Class A Common Stock), is allocated to noncontrolling interest (“NCI”) (see Note 8). The term “BellRing” as used herein generally refers to BellRing Brands, Inc.; however, in discussions related to debt facilities, the term “BellRing” refers to BellRing Brands, LLC. On October 1, 2018, 8th Avenue was separately capitalized by Post and third parties through a series of transactions (the “8th Avenue Transactions”), and 8th Avenue became the holding company for Post’s historical private brands business. Post received gross proceeds of $875.0, as well as $16.8 related to final working capital adjustments, from the 8th Avenue Transactions, and the Company retained shares of common stock equal to 60.5% of the common equity in 8th Avenue. Effective October 1, 2018, 8th Avenue was no longer consolidated in the Company's financial statements and the 60.5% retained interest in 8th Avenue is accounted for using the equity method. 8th Avenue is reported historically herein as Post’s Private Brands segment. For additional information, see Notes 6, 8 and 17. Unless otherwise stated or the context otherwise indicates, all references in these financial statements and notes to “Post,” “the Company,” “us,” “our” or “we” mean Post Holdings, Inc. and its consolidated and non-consolidated subsidiaries. Certain prior year amounts have been reclassified to conform with the fiscal 2020 presentation. These reclassifications had no impact on Net Earnings or Shareholders’ Equity, as previously reported.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Signifcant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation — The consolidated financial statements include the operations of Post and its wholly-owned and majority-owned subsidiaries. All intercompany transactions have been eliminated. Use of Estimates and Allocations — The consolidated financial statements of the Company are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), which require certain elections as to accounting policy, estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent liabilities at the dates of the financial statements and the reported amount of net revenues and expenses during the reporting periods. Significant accounting policy elections, estimates and assumptions include, among others, pension and benefit plan assumptions, valuation assumptions of goodwill and other intangible assets, marketing programs, self-insurance reserves and income taxes. Actual results could differ from those estimates. Business Combinations — The Company uses the acquisition method in accounting for acquired businesses. Under the acquisition method, the Company’s financial statements reflect the operations of an acquired business starting from the completion of the acquisition. The assets acquired and liabilities assumed are recorded at their respective estimated fair values at the date of the acquisition. Any excess of the purchase price over the estimated fair values of the identifiable net assets acquired is recorded as goodwill. Any excess of the estimated fair values of the identifiable net assets over the purchase price is recorded as a gain on bargain purchase. Cash Equivalents — Cash equivalents include all highly liquid investments with original maturities of less than three months. Restricted Cash — Restricted cash includes items such as cash deposits which serve as collateral for certain commodity hedging contracts as well as the Company’s high deductible workers’ compensation insurance program. Receivables — Receivables are reported at net realizable value. This value includes appropriate allowances for doubtful accounts, cash discounts and other amounts which the Company does not ultimately expect to collect. The Company determines its allowance for doubtful accounts based on historical losses as well as the economic status of and its relationship with its customers, especially those identified as “at risk.” A receivable is considered past due if payments have not been received within the agreed upon invoice terms. Receivables are written off against the allowance when the customer files for bankruptcy protection or are otherwise deemed to be uncollectible based upon the Company’s evaluation of the customer’s solvency. The Weetabix segment sells certain receivables to third party institutions without recourse. Receivables sold during the years ended September 30, 2020 and 2019 were $125.0 and $120.7, respectively. Inventories — Inventories, other than flocks, are generally valued at the lower of average cost (determined on a first-in, first-out basis) or net realizable value (“NRV”). Reported amounts have been reduced by an allowance for obsolete product and packaging materials based on a review of inventories on hand compared to estimated future usage and sales. Flock inventory represents the cost of purchasing and raising chicken flocks to egg laying maturity. The costs included in our flock inventory include the costs of the chicks, the feed fed to the birds and the labor and overhead costs incurred to operate the pullet facilities until the birds are transferred into the laying facilities, at which time their cost is amortized to operations, as cost of goods sold, over their expected useful lives of one to two years. Restructuring Expenses — Restructuring charges principally consist of severance, accelerated stock compensation and other employee separation costs and accelerated depreciation. The Company recognizes restructuring obligations and liabilities for exit and disposal activities at fair value in the period the liability is incurred. Employee severance costs are expensed when they become probable and reasonably estimable under established severance plans. Depreciation expense related to assets that will be disposed of or idled as a part of the restructuring activity is accelerated through the expected date of the asset shut down. See Note 5 for information about restructuring expenses. Property — Property is recorded at cost, and depreciation expense is generally provided on a straight-line basis over the estimated useful lives of the properties. Estimated useful lives range from 1 to 29 years for machinery and equipment; 1 to 38 years for buildings, building improvements and leasehold improvements; and 1 to 7 years for software. Total depreciation expense was $209.6, $218.3 and $221.0 in fiscal 2020, 2019 and 2018, respectively. Any gains and losses incurred on the sale or disposal of assets are included in “Other operating expenses, net” in the Consolidated Statements of Operations. Repair and maintenance costs incurred in connection with ongoing and planned major maintenance activities are accounted for under the direct expensing method. Property consisted of: September 30, 2020 2019 Land and land improvements $ 93.1 $ 91.1 Buildings and leasehold improvements 880.5 796.7 Machinery and equipment 1,766.8 1,595.8 Software 111.4 106.0 Construction in progress 127.4 147.3 2,979.2 2,736.9 Accumulated depreciation (1,199.5) (1,000.9) $ 1,779.7 $ 1,736.0 Other Intangible Assets — Other intangible assets consist primarily of customer relationships, trademarks and brands acquired in business combinations and include both indefinite and definite-lived assets. Amortization expense related to definite-lived intangible assets, which is provided on a straight-line basis over the estimated useful lives of the assets, was $160.3, $161.3 and $177.4 in fiscal 2020, 2019 and 2018, respectively. For the definite-lived intangible assets recorded as of September 30, 2020, amortization expense of $160.4, $160.4, $160.2, $159.0 and $157.7 is expected for fiscal 2021, 2022, 2023, 2024 and 2025, respectively. Other intangible assets consisted of: September 30, 2020 September 30, 2019 Carrying Accum. Net Carrying Accum. Net Subject to amortization: Customer relationships $ 2,304.8 $ (681.9) $ 1,622.9 $ 2,297.2 $ (562.2) $ 1,735.0 Trademarks and brands 795.0 (266.9) 528.1 793.7 (225.2) 568.5 Other 3.1 (3.1) — 3.1 (3.1) — 3,102.9 (951.9) 2,151.0 3,094.0 (790.5) 2,303.5 Not subject to amortization: Trademarks and brands 1,046.5 — 1,046.5 1,035.0 — 1,035.0 $ 4,149.4 $ (951.9) $ 3,197.5 $ 4,129.0 $ (790.5) $ 3,338.5 Recoverability of Assets — The Company continually evaluates whether events or circumstances have occurred which might impair the recoverability of the carrying value of its assets, including property, identifiable intangibles, goodwill and right-of-use (“ROU”) assets. Trademarks with indefinite lives are reviewed for impairment during the fourth quarter of each fiscal year following the annual forecasting process, or more frequently if facts and circumstances indicate the trademark may be impaired. The trademark impairment tests require the Company to estimate the fair value of the trademark and compare it to its carrying value. The estimated fair value is determined using an income-based approach (the relief-from-royalty method), which requires significant assumptions for each brand, including estimates regarding future revenue growth, discount rates and royalty rates. Assumptions are determined after consideration of several factors for each brand, including profit levels, research of external royalty rates by third party experts and the relative importance of each brand to the Company. Revenue growth assumptions are based on historical trends and management’s expectations for future growth by brand. The discount rate is based on a weighted-average cost of capital utilizing industry market data of similar companies. In addition, definite-lived assets and indefinite-lived intangible assets are reassessed as needed when information becomes available that is believed to negatively impact the fair market value of an asset. In general, an asset is deemed impaired and written down to its fair value if estimated related future cash flows are less than its carrying amount. See Note 7 for information about goodwill impairments. For the year ended September 30, 2020, the Company conducted impairment reviews and concluded there was no impairment of other intangible assets as of September 30, 2020. At Septembe r 30, 2019, the Company recorded a definite-lived intangible impairment charge of $14.6 for the All Whites trademark in the Refrigerated Retail segment to adjust its carrying value to zero. The impairment charge for the All Whites trademark was the result of a strategic decision made by new Refrigerated Retail management in the fourth quarter of fiscal 2019 to discontinue use of the brand name. All products previously sold under the All Whites brand name are now being marketed and sold under the Bob Evans Egg Whites brand name. At September 30, 2018, the Company recorded an indefinite-lived intangible impairment charge of $124.9 for the Weetabix trademark to adjust its carrying value to its estimated fair value of $261.8. The impairment charge for the Weetabix trademark was a result of reduced branded cereal volumes related to Weetabix’s pricing reset and shifting consumer preferences to private label products. These fair value measurements fall within Level 3 of the fair value hierarchy as described in Note 15. The trademark impairment losses are reported in “Impairment of goodwill and other intangible assets” in the Consolidated Statements of Operations. Deferred Compensation Investments — The Company funds a portion of its deferred compensation liability by investing in certain mutual funds in the same amounts as selected by the participating employees. Because management’s intent is to invest in a manner that matches the deferral options chosen by the participants and those participants can elect to transfer amounts into or out of each of the designated deferral options at any time, these investments have been classified as trading assets and are stated at fair value in “Prepaid expenses and other current assets” and “Other assets” on the Consolidated Balance Sheets (see Note 15). Both realized and unrealized gains and losses on these assets are included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations and offset the related change in the deferred compensation liability. Derivative Financial Instruments — In the ordinary course of business, the Company is exposed to commodity price risks relating to the acquisition of raw materials and supplies, interest rate risks relating to floating rate debt and foreign currency exchange rate risks. The Company utilizes derivative financial instruments, including (but not limited to) futures contracts, option contracts, forward contracts and swaps, to manage certain of these exposures by hedging when it is practical to do so. The Company does not hold or issue financial instruments for speculative or trading purposes. The Company’s derivative programs include strategies that qualify and strategies that do not qualify for hedge accounting treatment. To qualify for hedge accounting, the hedging relationship, both at inception of the hedge and on an ongoing basis, is expected to be highly effective in achieving offsetting changes in the fair value of the hedged risk during the period that the hedge is designated. All derivatives are recognized on the balance sheet at fair value. For derivatives that qualify for hedge accounting, the derivative is designated as a hedge on the date in which the derivative contract is entered. A derivative could be designated as a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge) or a hedge of a net investment in a foreign operation. Some derivatives may also be considered natural hedging instruments, where changes in their fair value act as economic offsets to changes in fair value of the underlying hedged item and are not designated for hedge accounting. The effective portion of gains and losses on cash flow hedges are recorded in other comprehensive income (“OCI”), until earnings are affected by the variability of cash flows. If the hedge is no longer effective, all changes in the fair value of the derivative are included in earnings for each period until the instrument matures. If a derivative is used as a hedge of a net investment in a foreign operation, its changes in fair value, to the extent effective as a hedge, are recorded in OCI. The amounts recorded in OCI related to a net investment hedge would be recognized in earnings in the event the foreign operation is liquidated. Any ineffective portion of designated hedges is recognized in earnings. Changes in the fair value of derivatives that are not designated for hedge accounting are recognized in earnings. Cash flows from derivatives that are accounted for as hedges and cash flows on derivatives utilized as economic hedges are classified in the same category on the Consolidated Statements of Cash Flows as the item being hedged or on a basis consistent with the nature of the instrument. Leases — In conjunction with the adoption of Accounting Standards Update (“ASU”) 2016-02, “Leases (Topic 842),” and ASU 2018-11, “Leases (Topic 842): Targeted Improvements,” on October 1, 2019, the policy for lease accounting was updated. See Note 16 for a summary of the updated policy. Revenue — In conjunction with the adoption of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” on October 1, 2018, the policy for recognizing revenue was updated. For fiscal 2020 and 2019, a summary of the policy for recognizing revenue was as follows: The Company recognizes revenue when performance obligations have been satisfied by transferring control of the goods to customers. Control is generally transferred upon delivery of the goods to the customer. At the time of delivery, the customer is invoiced using previously agreed-upon credit terms. Shipping and/or handling costs that occur before the customer obtains control of the goods are deemed fulfillment activities and are accounted for as fulfillment costs. The Company’s contracts with customers generally contain one performance obligation. Many of the Company’s contracts with customers include some form of variable consideration. The most common forms of variable consideration are trade promotions, rebates and discounts. Variable consideration is treated as a reduction of revenue at the time product revenue is recognized. Depending on the nature of the variable consideration, the Company uses either the “expected value” or the “most likely amount” method to determine variable consideration. The Company does not believe that there will be significant changes to its estimates of variable consideration when any uncertainties are resolved with customers. The Company reviews and updates estimates of variable consideration quarterly. Uncertainties related to the estimates of variable consideration are resolved in a short time frame and do not require any additional constraint on variable consideration. The Company’s products are sold with no right of return, except in the case of goods which do not meet product specifications or are damaged. No services beyond this assurance-type warranty are provided to customers. Customer remedies include either a cash refund or an exchange of the product. As a result, the right of return and related refund liability is estimated and recorded as a reduction of revenue based on historical sales return experience. For fiscal 2018, a summary of the policy for recognizing revenue was as follows: Revenue is recognized when title of goods and risk of loss is transferred to the customer, as specified by the shipping terms. Net sales reflect gross sales, including amounts billed to customers for shipping and handling, less sales discounts and trade allowances (including promotional price buy downs and new item promotional funding). Customer trade allowances are generally computed as a percentage of gross sales. Products are generally sold with no right of return, except in the case of goods which do not meet product specifications or are damaged, and related reserves are maintained based on return history. If additional rights of return are granted, revenue recognition is deferred. Estimated reductions to revenue for customer incentive offerings are based upon customer redemption history. The following table summarizes the impact of the Company’s adoption of Accounting Standards Codification (“ASC”) Topic 606 on a modified retrospective basis in the Company’s Consolidated Statement of Operations for the year ended September 30, 2019, the year of adoption. As a result of the adoption, certain payments to customers totaling $26.1 in the year ended September 30, 2019 previously classified in “Selling, general, and administrative expenses” were classified as “Net Sales” in the Consolidated Statement of Operations. These payments to customers relate to trade advertisements that support the Company’s sales to customers. In accordance with ASC Topic 606, these payments were determined not to be distinct within the customer contracts and, as such, require classification within net sales. Additionally, in the year ended September 30, 2019, the Company recognized revenue of $1.2 that was deferred upon the adoption of ASC Topic 606 in accordance with the satisfaction of the related performance obligation. The recognition of unearned revenue is included in “Net Sales” in the Company’s Consolidated Statement of Operations for the year ended September 30, 2019. No material changes to the balance sheet were required by the adoption of ASC Topic 606. Year Ended September 30, 2019 As Reported Under Topic 606 As Reported Under Prior Guidance Impact of Adoption Net Sales $ 5,681.1 $ 5,706.0 $ (24.9) Cost of goods sold 3,889.0 3,889.0 — Gross Profit 1,792.1 1,817.0 (24.9) Selling, general and administrative expenses 911.6 937.7 (26.1) Amortization of intangible assets 161.3 161.3 — Gain on sale of business (126.6) (126.6) — Impairment of goodwill and other intangible assets 63.3 63.3 — Other operating expenses, net 1.5 1.5 — Operating Profit $ 781.0 $ 779.8 $ 1.2 Cost of Goods Sold — Cost of goods sold includes, among other things, inbound and outbound freight costs (including the Company-owned fleet) and depreciation expense related to assets used in production, while storage and other warehousing costs are included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. Storage and other warehousing costs totaled $177.8, $170.1 and $169.4 in fiscal 2020, 2019 and 2018, respectively. Advertising — Advertising costs are expensed as incurred except for costs of producing media advertising, such as television commercials or magazine and online advertisements, which are deferred until the first time the advertising takes place and amortized to the statement of operations over the time the advertising takes place. The amounts reported as assets on the Consolidated Balance Sheets as “Prepaid expenses and other current assets” were $1.3 and $3.9 as of September 30, 2020 and 2019, respectively. Stock-based Compensation — The Company recognizes the cost of employee services received in exchange for awards of equity instruments based on the grant-date fair value of equity awards and the fair market value at each quarterly reporting date for liability awards. That cost is recognized over the period during which an employee is required to provide service in exchange for the award — the requisite service period (usually the vesting period). Any forfeitures of stock-based awards are recorded as they occur. See Note 20 for disclosures related to stock-based compensation. Income Taxes — Income tax expense (benefit) is estimated based on income taxes in each jurisdiction and includes the effects of both current tax exposures and the temporary differences resulting from differing treatment of items for tax and financial reporting purposes. These temporary differences result in deferred tax assets and liabilities. A valuation allowance is

Recently Issued and Adopted Acc

Recently Issued and Adopted Accounting Standards	12 Months Ended
	Sep. 30, 2020
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements and Changes in Accounting Principles	RECENTLY ISSUED AND ADOPTED ACCOUNTING STANDARDS The Company has considered all new accounting pronouncements and has concluded there are no new pronouncements (other than the ones described below) that had or will have an impact on the results of operations, OCI, financial condition, cash flows, shareholders’ equity or disclosures based on current information. Recently Issued In March 2020, the Financial Accounting Standards Board (the “FASB”) issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” This ASU provides optional expedients and exceptions for contracts, hedging relationships and other transactions that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued because of reference rate reform. The expedients and exceptions provided by this ASU do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022. This ASU is elective and effective for all entities as of March 12, 2020, the date this ASU was issued. An entity may elect to apply the amendments for contract modifications provided by this ASU as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020. Once elected, this ASU must be applied prospectively for all eligible contract modifications. The Company is currently evaluating the impact of this ASU as it relates to its debt and hedging relationships that reference LIBOR. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” This ASU provides guidance on the measurement of credit losses for most financial assets and certain other instruments. This ASU replaces the current incurred loss impairment approach with a methodology to reflect expected credit losses and requires consideration of a broader range of reasonable and supportable information to explain credit loss estimates. This ASU is effective for annual periods beginning after December 15, 2019 and interim periods therein (i.e., Post’s financial statements for the year ending September 30, 2021). The Company has substantially completed its analysis of this ASU’s impact on its trade receivables. The Company will adopt this ASU on October 1, 2020, and does not expect it to have a material impact on its consolidated financial statements. Recently Adopted In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” This ASU simplifies the accounting for income taxes by removing certain exceptions for recognizing deferred taxes for investments, performing intra-period allocations and calculating income taxes in interim periods. The Company early adopted this ASU as of June 30, 2020 on a prospective basis, as permitted by the ASU. The adoption of this ASU did not have a material impact on the Company’s financial statements. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” This ASU requires a company to recognize ROU assets and lease liabilities on its balance sheet and disclose key information about leasing arrangements. ASU 2016-02 offers specific accounting guidance for lessees, lessors and sale and leaseback transactions. Lessees and lessors are required to disclose qualitative and quantitative information about leasing arrangements to enable a user of the financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. In July 2018, the FASB issued ASU 2018-11, “Leases (Topic 842): Targeted Improvements.” This ASU provides an additional transition method by allowing entities to initially apply the new lease standard at the date of adoption with a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. This ASU also gives lessors the option of electing, as a practical expedient by class of underlying asset, not to separate the lease and non-lease components of a contract when those lease contracts meet certain criteria. The Company adopted these ASUs on October 1, 2019, as required by these ASUs, and utilized the cumulative effect adjustment approach. At adoption, the Company recognized ROU assets and lease liabilities of $158.1 and $168.2, respectively, on the balance sheet at October 1, 2019. The adoption of these ASUs did not materially impact the statements of operations or cash flows. In addition, the Company provides expanded disclosures related to its leasing arrangements in accordance with these ASUs. For additional information, refer to Note 16.

Business Combinations

Business Combinations	12 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Business Combinations	BUSINESS COMBINATIONS The Company accounts for business combinations using the acquisition method of accounting, whereby the results of operations are included in the financial statements from the date of acquisition. The purchase price is allocated to acquired assets and assumed liabilities based on their estimated fair values at the date of acquisition. Any excess of the purchase price over the estimated fair values of the identifiable net assets acquired is recorded as goodwill. Any excess of the estimated fair values of the identifiable net assets over the purchase price is recorded as a gain on bargain purchase. Goodwill represents the value the Company expects to achieve through the implementation of operational synergies and the expansion of the business into new or growing segments of the industry. Fiscal 2020 On July 1, 2020, the Company completed its acquisition of Henningsen Foods, Inc. (“Henningsen”) from a subsidiary of Kewpie Corporation for $20.0, subject to working capital and other adjustments, resulting in a payment at closing of $22.7. The acquisition was completed using cash on hand. At September 30, 2020, the Company recorded an estimated working capital settlement receivable of $1.8, which was included in “Receivables, net” on the Consolidated Balance Sheet. Henningsen is a producer of egg and meat products and is reported in the Foodservice segment (see Note 22). Based upon the preliminary purchase price allocation, the Company identified and recorded $32.6 of net assets, including cash of $2.8, which exceeded the purchase price paid for Henningsen. As a result, the Company recorded a gain of $11.7, which was included in “Other operating (income) expenses, net” in the Consolidated Statement of Operations for the year ended September 30, 2020. Fiscal 2018 On January 12, 2018, the Company completed its acquisition of Bob Evans Farms, Inc. (“Bob Evans”), resulting in the Company owning all of the outstanding shares of Bob Evans common stock. The Company paid each holder of shares of Bob Evans common stock, other than holders who demanded appraisal of their shares of Bob Evans common stock under Delaware law and had not withdrawn their demands as of the closing date, $77.00 per share, resulting in a payment at closing of $1,381.2 (which, in addition to the amounts paid to Bob Evans stockholders, includes amounts paid to retire certain debt and other obligations of Bob Evans). Any shares of Bob Evans common stock subject to appraisal as of the closing date were canceled and no longer outstanding after closing. The closing payment did not include any amounts due to former holders of approximately 4.35 shares of Bob Evans common stock who demanded appraisal under Delaware law and had not withdrawn their demands as of the closing date. In December 2018, the Company made payments of $257.6 to the former holders of Bob Evans common stock who had demanded appraisal and had not been paid for their shares of Bob Evans common stock. The payments constituted a settlement with one former stockholder as well as prepayments of the $77.00 per share merger consideration to the remaining former stockholders who had held 2.5 shares of Bob Evans common stock. In September 2019, the Company reached settlement terms on a confidential basis with the remaining former stockholders, and had an accrual of $19.1, which was recorded as “Other current liabilities,” on the Consolidated Balance Sheet at September 30, 2019. The final payments were made by the Company on October 1, 2019. In connection with the fiscal 2019 settlements, the Company recorded expense of $9.7, which was included in “Selling, general and administrative expenses” and “Interest expense, net” in the Consolidated Statement of Operations for the year ended September 30, 2019. In the year ended September 30, 2018, the Company recorded interest expense of $13.4 related to these shares, which was included in “Interest expense, net” in the Consolidated Statement of Operations. No such accruals or expense were recorded for the year ended September 30, 2020. For additional information regarding the proceedings brought by former holders of Bob Evans common stock who demanded appraisal of their shares of Bob Evans common stock under Delaware law, refer to Note 18. Bob Evans is a producer of refrigerated potato and pasta side dishes, pork sausage and a variety of refrigerated and frozen convenience food items. The acquisition strengthened the Company’s position in the foodservice and refrigerated retail channels. Bob Evans is reported in two reportable segments. The results of Bob Evans’s foodservice operations are reported in the Foodservice segment, and the results of Bob Evans’s retail operations are reported in the Refrigerated Retail segment (see Note 22). Based upon the purchase price allocation, the Company recorded $376.0 of customer relationships to be amortized over a weighted-average period of 18 years, $6.0 of definite-lived trademarks to be amortized over a weighted-average period of 10 years and $400.0 of indefinite-lived trademarks. The goodwill generated by the Company’s acquisition of Bob Evans is not deductible for U.S. federal income tax purposes; however, $13.8 of goodwill generated by business combinations completed by Bob Evans in periods prior to its acquisition was transferred to Post and is tax deductible. The following table provides the final allocation of the purchase price related to the fiscal 2018 acquisition of Bob Evans based upon the fair value of assets and liabilities assumed, including the provisional amounts recognized related to the acquisition as of September 30, 2018, as well as measurement period adjustments made during the first quarter of fiscal 2019. The allocation of purchase price was finalized as of December 31, 2018, and no additional adjustments have been or will be made. Acquisition Date Amounts Recognized as of September 30, 2018 (a) Adjustments During Fiscal 2019 Acquisition Date Amounts Recognized (as Adjusted) Cash and cash equivalents $ 15.6 $ — $ 15.6 Receivables 58.5 — 58.5 Inventories 27.1 — 27.1 Prepaid expenses and other current assets 34.3 — 34.3 Property 184.3 — 184.3 Goodwill 898.3 (0.7) 897.6 Other intangible assets 782.0 — 782.0 Other assets 0.4 — 0.4 Accounts payable (18.2) — (18.2) Other current liabilities (58.5) — (58.5) Deferred tax liability - long-term (194.9) 0.7 (194.2) Other liabilities (5.3) — (5.3) Total acquisition cost (b) $ 1,723.6 $ — $ 1,723.6 (a) As previously reported in Post’s Annual Report on Form 10-K for fiscal 2018 filed with the Securities and Exchange Commission (the “SEC”) on November 16, 2018. (b) Total acquisition cost is comprised of $1,381.2 paid at closing and additional payments of $342.4, which includes payments to former holders of shares of Bob Evans common stock who exercised appraisal rights, payments in connection with Bob Evans deferred compensation plans and payments to compensate Bob Evans employees due to the cancellation of their outstanding employee stock awards. Acquisition-Related Expenses The Company incurs transaction-related expenses in conjunction with both completed and contemplated acquisitions. These expenses generally include third party costs for due diligence, advisory services and transaction success fees. During the years ended September 30, 2020, 2019 and 2018, the Company incurred transaction-related expenses of $3.8, $8.9 and $23.4, respectively, which were recorded in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. Unaudited Pro Forma Information The following unaudited pro forma information presents a summary of the combined results of operations of the Company and the aggregate results of all businesses acquired in fiscal 2018 for the period presented as if the acquisition of Bob Evans had occurred on October 1, 2016. These pro forma adjustments give effect to the amortization of certain definite-lived intangible assets, adjusted depreciation based upon fair value of assets acquired, interest expense related to the financing of the business combinations, inventory revaluation adjustments on acquired businesses, acquisition costs and related income taxes. The following unaudited pro forma information has been prepared for comparative purposes only and is not necessarily indicative of the results of operations as they would have been had the acquisition occurred on the assumed date, nor is it necessarily an indication of future operating results. 2018 Pro forma net sales $ 6,423.8 Pro forma net earnings available to common shareholders $ 486.4 Pro forma basic earnings per share $ 7.30 Pro forma diluted earnings per share $ 6.54

Restructuring

Restructuring	12 Months Ended
	Sep. 30, 2020
Restructuring and Related Activities [Abstract]
Restructuring	RESTRUCTURING In February 2018, the Company announced its plan to close its Post Consumer Brands RTE cereal manufacturing facility in Clinton, Massachusetts (the “Clinton Facility”). The transfer of production capabilities to other Post Consumer Brands facilities and the closure of the Clinton Facility was completed at September 30, 2019. Final cash payments for employee-related costs were made in the first quarter of fiscal 2020. No additional restructuring costs were incurred in fiscal 2020. For additional information on assets held for sale related to the closure, see Note 6. Amounts related to the restructuring events are shown in the following table. All costs are recognized in “Selling, general and administrative expenses” in the Consolidated Statements of Operations with the exception of accelerated depreciation expense, which is included in “Cost of goods sold.” These expenses are not included in the measure of segment performance for any segment (see Note 22). Employee-Related Costs Accelerated Depreciation Total Balance, September 30, 2017 $ — $ — $ — Charge to expense 2.7 2.5 5.2 Non-cash charges — (2.5) (2.5) Balance, September 30, 2018 $ 2.7 $ — $ 2.7 Charge to expense 2.2 7.4 9.6 Cash payments (4.8) — (4.8) Non-cash charges — (7.4) (7.4) Balance, September 30, 2019 $ 0.1 $ — $ 0.1 Cash payments (0.1) — (0.1) Balance, September 30, 2020 $ — $ — $ — Total expected restructuring charge $ 4.9 $ 9.9 $ 14.8 Cumulative incurred to date 4.9 9.9 14.8 Remaining expected restructuring charge $ — $ — $ —

Divestitures and Amounts Held F

Divestitures and Amounts Held For Sale	12 Months Ended
	Sep. 30, 2020
Assets and Liabilities Held for Sale [Abstract]
Divestitures and Amounts Held For Sale	DIVESTITURES AND AMOUNTS HELD FOR SALE Divestiture On October 1, 2018, 8th Avenue was separately capitalized through the 8th Avenue Transactions, and 8th Avenue became the holding company for Post’s historical private brands business. Post received gross proceeds of $875.0 from the 8th Avenue Transactions, as well as $16.8 related to final working capital adjustments, retaining shares of common stock equal to 60.5% of the common equity in 8th Avenue. Post’s gross proceeds consisted of (i) $250.0 from a third party and (ii) $625.0 from a committed senior increasing rate bridge loan (the “2018 Bridge Loan”), which was funded in fiscal 2018 prior to the closing of the 8th Avenue Transactions (see Note 17). A third party received 2.5 shares of 8th Avenue preferred stock with an 11% cumulative, quarterly compounding dividend and a $100.00 per share liquidation value and shares of common stock equal to 39.5% of the common equity in 8th Avenue. During the year ended September 30, 2019, the Company recorded a gain of $126.6 related to the 8th Avenue Transactions, which was reported as “Gain on sale of business” in the Consolidated Statement of Operations. The gain included foreign exchange losses previously recorded in accumulated OCI of $42.1. Effective October 1, 2018, 8th Avenue was no longer consolidated in the Company’s financial statements and the 60.5% common equity retained interest in 8th Avenue is accounted for using the equity method. For additional information regarding the Company’s equity method investment in 8th Avenue, refer to Note 8. The Company incurred third party costs attributable to the 8th Avenue Transactions of $9.9 and $12.4 in the years ended September 30, 2019 and 2018, respectively, which were included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. No third party costs attributable to the 8th Avenue Transactions were incurred by the Company during the year ended September 30, 2020. In order to calculate the total recorded gain related to the 8th Avenue Transactions of $126.6, management was required to estimate the fair value of the Company’s equity method investment in 8th Avenue. In making this estimate, management used an approach combining the estimated implied value from the 8th Avenue Transactions, an income approach and a market approach, in which the greatest value was placed on the implied value from the 8th Avenue Transactions. In order to calculate the fair value implied by the 8th Avenue Transactions, management was required to estimate the value of the 8th Avenue equity. In making this estimate, management used a lattice model, which required significant assumptions, including estimates for the term, credit spread, yield volatility and risk-free rates associated with 8th Avenue’s preferred stock. The income approach was based on discounted future cash flows and required significant assumptions, including estimates regarding future revenue, profitability and capital requirements. The market approach was based on a market multiple (revenue and EBITDA, which stands for earnings before interest, income taxes, depreciation and amortization) and required an estimate of appropriate multiples based on the market data. Amounts Held For Sale In connection with the closure of the Clinton Facility (see Note 5), the Company had a manufacturing plant (the “Clinton Plant”) classified as held for sale with a book value of $3.4 and $8.4 at September 30, 2020 and 2019, respectively. The Company sold a portion of the Clinton Plant in March 2020. Additionally, the Company had land and a building with a combined book value of $1.4 and $1.5 classified as held for sale at its Post Consumer Brands manufacturing facility in Asheboro, North Carolina (the “Asheboro Facility”) at September 30, 2020 and 2019, respectively, and land and a building with a book value of $2.5 classified as held for sale at one of its Weetabix manufacturing facilities in Corby, United Kingdom (the “Corby Facility”) at September 30, 2020. In accordance with ASC Topic 360, “Property, Plant and Equipment,” these assets were classified as current and were reported as “Prepaid expenses and other current assets” on the Consolidated Balance Sheets. In the year ended September 30, 2020, a loss on assets held for sale of $2.7 was recorded consisting of losses of $2.6 and $0.1 related to the Clinton Plant and Asheboro Facility, respectively, and was included in “Other operating (income) expenses, net” in the Consolidated Statement of Operations. In the year ended September 30, 2019, a held for sale net gain of $124.6 was recorded consisting of (i) a gain of $126.6, which was reported as “Gain on sale of business,” and a loss of $2.6, which was included in “Loss on extinguishment of debt, net,” in the Consolidated Statement of Operations related to the 8th Avenue Transactions and (ii) a gain of $0.6, which was recorded related to the sale of the Company’s cereal warehouse at its Clinton Facility and was included in “Other operating (income) expenses, net” in the Consolidated Statement of Operations. There were no held for sale gains or losses recorded in the year ended September 30, 2018.

Goodwill

Goodwill	12 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL The changes in the carrying amount of goodwill by segment are noted in the following table. Post Consumer Brands Weetabix Foodservice Refrigerated Retail BellRing Brands Total Balance, September 30, 2018 Goodwill (gross) $ 2,012.0 $ 900.9 $ 1,336.1 $ 793.8 $ 180.7 $ 5,223.5 Accumulated impairment losses (609.1) — — — (114.8) (723.9) Goodwill (net) $ 1,402.9 $ 900.9 $ 1,336.1 $ 793.8 $ 65.9 $ 4,499.6 Impairment loss — — — (48.7) — (48.7) Acquisition related adjustment — — (0.5) (0.2) — (0.7) Currency translation adjustment (0.2) (50.2) — — — (50.4) Balance, September 30, 2019 Goodwill (gross) $ 2,011.8 $ 850.7 $ 1,335.6 $ 793.6 $ 180.7 $ 5,172.4 Accumulated impairment losses (609.1) — — (48.7) (114.8) (772.6) Goodwill (net) $ 1,402.7 $ 850.7 $ 1,335.6 $ 744.9 $ 65.9 $ 4,399.8 Currency translation adjustment — 38.8 — — — 38.8 Balance, September 30, 2020 Goodwill (gross) $ 2,011.8 $ 889.5 $ 1,335.6 $ 793.6 $ 180.7 $ 5,211.2 Accumulated impairment losses (609.1) — — (48.7) (114.8) (772.6) Goodwill (net) $ 1,402.7 $ 889.5 $ 1,335.6 $ 744.9 $ 65.9 $ 4,438.6 Goodwill represents the excess of the cost of acquired businesses over the fair market value of their identifiable net assets. The Company conducts a goodwill impairment qualitative assessment during the fourth quarter of each fiscal year following the annual forecasting process, or more frequently if facts and circumstances indicate that goodwill may be impaired. The goodwill impairment qualitative assessment requires an analysis to determine if it is more likely than not that the fair value of the business is less than its carrying amount. If adverse qualitative trends are identified that could negatively impact the fair value of the business, a quantitative goodwill impairment test is performed. In fiscal 2020, we elected not to perform a qualitative assessment and instead performed a quantitative impairment test for all reporting units, except for BellRing Brands. The Company performed a qualitative test for the BellRing Brands reporting unit, and determined there were no adverse trends that could negatively impact the fair value of the business. In fiscal 2019 and 2018, the Company elected not to perform a qualitative assessment and instead performed a quantitative impairment test for all reporting units. The estimated fair value is determined using a combined income and market approach with a greater weighting on the income approach. The income approach is based on discounted future cash flows and requires significant assumptions, including estimates regarding future revenue, profitability, capital requirements and discount rates. The market approach is based on a market multiple (revenue and EBITDA) and requires an estimate of appropriate multiples based on market data. The Company did not record a goodwill impairment charge at September 30, 2020, as all reporting units subjected to the quantitat ive test passed. At September 30, 2020, the estimated fair values of all such reporting units exceeded their carrying values by at least 4% (the lowest of which was Foodservice, all others exceeded their carrying values by at least 13%). Variances between the actual performance of the businesses and the assumptions that were used in d eveloping the estimates of fair value could result in impairment charges in future periods. Further, due to the low headroom in the Foodservice reporting unit, small changes in significant assumptions may have resulted in an impairment in the current period. Factors that could create variances in the estimated fair value of the reporting units include but are not limited to (i) fluctuations in forecasted sales volumes, which can be driven by external factors affecting demand such as changes in consumer preferences, including changes related to the COVID-19 pandemic, and consumer responses to marketing and pricing strategy, (ii) changes in product costs, including commodities, (iii) interest rate fluctuations and (iv) currency fluctuations. For the year ended September 30, 2019, the Company recorded a charge of $48.7 for the impairment of goodwill. The impairment charge related to the Refrigerated Retail segment and was primarily related to lost distribution with customers and a shift in supplier and consumer preferences to private label cheese products and away from branded cheese products. The Company did not record a goodwill impairment charge at September 30, 2018, as all reporting units passed the quantitative impairment test. These fair value measurements fell within Level 3 of the fair value hierarchy (see Note 15). The goodwill impairment losses are aggregated with trademark impairment losses in “Impairment of goodwill and other intangible assets” in the Consolidated Statements of Operations.

Noncontrolling Interests, Equit

Noncontrolling Interests, Equity Interests and Related Party Transactions	12 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Noncontrolling Interests, Equity Interests and Related Party Transactions	NONCONTROLLING INTERESTS, EQUITY INTERESTS AND RELATED PARTY TRANSACTIONS BellRing As a result of the IPO on October 21, 2019 (see Note 1), the Company (other than BellRing and its subsidiaries) owned 71.2% of the BellRing LLC units and one share of Class B Common Stock. The Class B Common Stock has voting rights but no rights to dividends or other economic rights. For so long as the Company (other than BellRing and its subsidiaries) directly owns more than 50% of the BellRing LLC units, the Class B Common Stock represents 67% of the combined voting power of the BellRing Common Stock, which provides the Company control over BellRing’s board of directors and results in the full consolidation of BellRing and its subsidiaries into the Company’s financial statements. The remaining interest in BellRing’s consolidated net income and net assets will be allocated to NCI. The BellRing LLC units held by the Company include a redemption feature that allows the Company to, at BellRing LLC’s option (as determined by its board of managers), redeem BellRing LLC units for either (i) Class A Common Stock of BellRing or (ii) cash equal to the market value of the BellRing Class A Common Stock at the time of redemption. In the event the Company (other than BellRing and its subsidiaries) holds 50% or less of the BellRing LLC units, the holder of the share of Class B Common Stock will be entitled to a number of votes equal to the number of BellRing LLC units held by all persons other than BellRing and its subsidiaries. In such situation, the Company, as the holder of the share of Class B Common Stock, will only be entitled to cast a number of votes equal to the number of BellRing LLC units held by the Company (other than BellRing and its subsidiaries). Also, in such situation, if any BellRing LLC units are held by persons other than the Company, then the Company, as the holder of the share of Class B Common Stock, will cast the remainder of votes to which the share of Class B Common Stock is entitled only in accordance with the instructions and directions from such other holders of the BellRing LLC units. As of September 30, 2020, the Company owned 71.2% of the BellRing LLC units and the net income and net assets of BellRing and its subsidiaries were consolidated within the Company’s financial statements, and the remaining 28.8% of the consolidated net income and net assets of BellRing and its subsidiaries, representing the percentage of economic interest in BellRing LLC held by BellRing (and therefore indirectly held by the public stockholders of BellRing through their ownership of the Class A Common Stock), were allocated to NCI. The following table summarizes the effects of changes in ownership of BellRing on the Company’s equity: Year Ended September 30, 2020 Increase in additional paid-in capital related to net proceeds from IPO $ 524.4 Increase in additional paid-in capital related to establishment of noncontrolling interest 65.0 Decrease in additional paid-in capital related to tax effects of IPO (133.8) Net transfers from noncontrolling interest $ 455.6 8th Avenue In connection with the 8th Avenue Transactions (see Note 6), the Company has a 60.5% common equity retained interest in 8th Avenue that is accounted for using the equity method. In determining the accounting treatment of the retained interest, management concluded that 8th Avenue was not a variable interest entity as defined by ASC Topic 810, “Consolidation,” and as such, 8th Avenue was evaluated under the voting interest model. Based on the terms of 8th Avenue’s governing documents, management determined that the Company does not have a controlling voting interest in 8th Avenue due to substantive participating rights held by a third party associated with the governance of 8th Avenue. However, the Company does retain significant influence, and therefore, the use of the equity method of accounting is required. The following table presents the calculation of the Company’s equity method loss attributable to 8th Avenue: Year Ended September 30, 2020 2019 8th Avenue’s net loss available to 8th Avenue’s common shareholders $ (38.9) $ (46.7) 60.5 % 60.5 % Equity method loss available to Post $ (23.5) $ (28.3) Less: Amortization of basis difference, net of tax (a) 6.9 8.8 Equity method loss, net of tax $ (30.4) $ (37.1) (a) The Company adjusted the historical basis of 8th Avenue’s assets and liabilities to fair value and recognized a total basis difference of $70.3. The basis difference related to inventory of $2.0 , net of tax, was included in equity method loss in the year ended September 30, 2019. The basis difference related to property, plant and equipment and other intangible assets is being amortized over the weighted average useful lives of the assets. At September 30, 2020 and 2019, the remaining basis difference to be amortized was $54.6 and $61.5, respectively . Summarized financial information of 8th Avenue is presented in the following tables. Year Ended September 30, 2020 2019 Net sales $ 924.2 $ 838.5 Gross profit $ 160.0 $ 139.6 Net loss $ (6.4) $ (17.6) Less: Preferred stock dividend 32.5 29.1 Net Loss Available to 8th Avenue Common Shareholders $ (38.9) $ (46.7) Year Ended September 30, 2020 2019 Current assets $ 251.5 $ 209.2 Other assets 830.1 826.2 Total Assets $ 1,081.6 $ 1,035.4 Current portion of long-term debt $ 5.2 $ 5.2 Accounts payable and other current liabilities 113.3 74.4 Long-term debt 663.3 644.9 Other liabilities 71.6 76.5 Total Liabilities 853.4 801.0 Preferred stock 61.6 29.1 Other shareholders’ equity 166.6 205.3 Shareholders’ Equity 228.2 234.4 Total Liabilities and Shareholders’ Equity $ 1,081.6 $ 1,035.4 Prior to the 8th Avenue Transactions, Post’s historical private brands business used certain functions and services performed by the Company. These functions and services included information systems, sales and marketing, procurement, accounting shared services, legal, tax, human resources, payroll and cash management. After the completion of the 8th Avenue Transactions, the Company continues to provide many of these services to 8th Avenue under a master services agreement (the “MSA”). In addition, Post and a third party each provide certain advisory services to 8th Avenue for a fee. During the years ended September 30, 2020 and 2019, the Company recorded MSA and advisory income of $3.9 and $4.1, respectively, which was recorded in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. No such income was recorded in the year ended September 30, 2018. During the years ended September 30, 2020 and 2019, the Company had net sales to 8th Avenue of $5.7 and $4.7, respectively, and purchases from and royalties paid to 8th Avenue of $9.9 and $9.4, respectively. Sales and purchases between the Company and 8th Avenue were all made at arm’s-length. The investment in 8th Avenue was $110.1 and $140.5 at September 30, 2020 and 2019, respectively, and was included in “Equity method investments” on the Consolidated Balance Sheets. The Company had current receivables, current payables and a long-term liability with 8th Avenue of $3.2, $0.6 and $0.7, respectively, at September 30, 2020, and current receivables, current payables and a long-term liability of $5.1, $0.6 and $0.7, respectively, at September 30, 2019. The current receivables, current payables and long-term liability, which related to the separation of 8th Avenue from the Company, MSA fees, pass through charges owed by 8th Avenue to the Company and related party sales and purchases, were included in “Receivables, net,” “Accounts payable” and “Other liabilities,” respectively, on the Consolidated Balance Sheets. Alpen and Weetabix East Africa The Company holds an equity interest in two legal entities, Alpen Food Company South Africa (Pty) Limited (“Alpen”) and Weetabix East Africa Limited (“Weetabix East Africa”). Alpen is a South African-based company that produces RTE cereal and muesli. The Company owns 50% of Alpen’s common stock with no other indicators of control and, accordingly, the Company accounts for its investment in Alpen using the equity method. The Company’s equity method (loss) earnings, net of tax attributable to Alpen was $(0.5), $0.1 and $(0.3) for the years ended September 30, 2020, 2019 and 2018, respectively, and was included in “Equity method loss, net of tax” in the Consolidated Statements of Operations. The investment in Alpen was $4.0 and $5.0 at September 30, 2020 and 2019, respectively, and was included in “Equity method investments” on the Consolidated Balance Sheets. The Company had a note receivable balance with Alpen of $0.5 and $0.5 at September 30, 2020 and 2019, respectively, which was included in “Other assets” on the Consolidated Balance Sheets.

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income taxes	INCOME TAXES The components of “Earnings before Income Taxes and Equity Method Loss” on the Consolidated Statements of Operations and other summary information is presented in the following table. Year Ended September 30, 2020 2019 2018 Domestic $ (36.4) $ 80.4 $ 289.0 Foreign 99.8 78.7 (24.3) Earnings before Income Taxes and Equity Method Loss $ 63.4 $ 159.1 $ 264.7 Income tax expense (benefit) $ 3.5 $ (3.9) $ (204.0) Effective income tax rate 5.5 % (2.5) % (77.1) % The expense (benefit) for income taxes consisted of the following: Year Ended September 30, 2020 2019 2018 Current: Federal $ 31.3 $ 61.5 $ 27.3 State 7.1 2.6 5.2 Foreign 8.7 12.3 20.0 47.1 76.4 52.5 Deferred: Federal (45.6) (61.8) (253.5) State (14.5) (15.2) 21.4 Foreign 16.5 (3.3) (24.4) (43.6) (80.3) (256.5) Income tax expense (benefit) $ 3.5 $ (3.9) $ (204.0) A reconciliation of income tax expense (benefit) with amounts computed at the statutory federal rate follows: Year Ended September 30, 2020 2019 2018 Computed tax (a) $ 13.3 $ 33.4 $ 64.9 Enacted tax law and changes, including the Tax Act (a) (1.5) (4.8) (270.9) Non-deductible goodwill impairment loss — 6.9 — Non-deductible compensation 4.5 2.7 1.2 Transaction costs (1.1) 2.2 1.5 Domestic production activities deduction — — (5.9) State income tax (benefit) expense, net of effect on federal tax (4.3) (0.7) 5.6 Non-taxable interest income — — (2.4) Valuation allowances 5.0 6.6 4.1 Change in deferred tax rates 11.1 (4.6) 0.3 Uncertain tax positions 1.2 (7.9) 0.3 Net losses and basis difference attributable to equity method investment (6.5) 4.4 — Income tax credits (2.6) (3.0) (2.3) Rate differential on foreign income (10.8) (7.7) (5.3) Excess tax benefits for share-based payments (1.4) (33.4) (1.8) Gain on bargain purchase (2.5) — — Enhanced deduction for food donation (1.5) (0.6) (0.8) Return-to-provision (1.5) 0.6 (1.0) Other, net (none in excess of 5% of statutory tax) 2.1 2.0 8.5 Income tax expense (benefit) $ 3.5 $ (3.9) $ (204.0) (a) Fiscal 2020 and 2019 federal corporate income tax was computed at the federal statutory rate of 21%. Fiscal 2018 federal corporate income tax was computed using a blended U.S. federal corporate income tax rate of 24.5%, as discussed below. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax non-current assets (liabilities) were as follows: September 30, 2020 September 30, 2019 Assets Liabilities Net Assets Liabilities Net Derivative mark-to-market adjustments $ 133.8 $ — $ 133.8 $ 98.5 $ — $ 98.5 Disallowed interest carryforwards 36.0 — 36.0 29.7 — 29.7 Net operating loss and credit carryforwards 33.7 — 33.7 30.8 — 30.8 Lease liabilities 26.2 — 26.2 — — — Stock-based and deferred compensation 18.4 — 18.4 19.9 — 19.9 Accrued vacation, incentive and severance 8.3 — 8.3 7.7 — 7.7 Accrued liabilities 9.0 — 9.0 15.6 — 15.6 Inventory 3.2 — 3.2 6.2 — 6.2 Intangible assets — (619.9) (619.9) — (652.4) (652.4) Property — (192.3) (192.3) — (173.4) (173.4) Investment in partnership (a) — (144.6) (144.6) — — — ROU assets — (25.5) (25.5) — — — Basis difference attributable to equity method investment — (22.5) (22.5) — (30.0) (30.0) Pension and other postretirement benefits — (10.1) (10.1) — (11.2) (11.2) Other items 4.6 (1.7) 2.9 4.5 (1.8) 2.7 Total gross deferred income taxes 273.2 (1,016.6) (743.4) 212.9 (868.8) (655.9) Valuation allowance (41.1) — (41.1) (32.6) — (32.6) Total deferred taxes $ 232.1 $ (1,016.6) $ (784.5) $ 180.3 $ (868.8) $ (688.5) (a) The Company’s deferred tax liability for investment in partnership relates to excess financial reporting outside basis over tax outside basis in BellRing entities treated as partnerships for U.S. federal income tax purposes. As of September 30, 2020, the Company had U.S. federal net operating loss (“NOL”) carryforwards totaling approximately $41.8, which have expiration dates beginning in fiscal 2022 and extending through fiscal 2034, as well as state NOL carryforwards totaling approximately $576.4, which have expiration dates beginning in fiscal 2021 and extending through fiscal 2040. As of September 30, 2020, the Company had NOL carryforwards in foreign jurisdictions of $12.7. As certain of these NOLs and carryforwards were acquired through acquisitions, the deductibility of the NOLs is subject to limitation under section 382 of the Internal Revenue Code (“IRC”) and similar limitations under state tax law. Giving consideration to IRC section 382 and state limitations, the Company believes it will generate sufficient taxable income to fully utilize the U.S. federal and certain state NOLs before they expire. As of September 30, 2020, approximately $23.4 of the deferred tax asset related to the state NOLs has been offset by a valuation allowance based on management’s judgment that it is more likely than not that the benefits of those deferred tax assets will not be realized in the future. No provision has been made for income taxes on undistributed earnings of consolidated foreign subsidiaries of $118.2 at September 30, 2020, as it is the Company’s intention to indefinitely reinvest undistributed earnings of its foreign subsidiaries. It is not practicable to estimate the additional income taxes and applicable foreign withholding taxes that would be payable on the remittance of such undistributed earnings. CARES Act On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security (“CARES”) Act was enacted and signed into law. Certain provisions of the CARES Act impacted the Company’s accounting for income taxes, such as modifications to the limitation of business interest expense deductibility for tax years beginning in 2019 and 2020, and have been accounted for within the year ended September 30, 2020. The CARES Act did not have a material impact on the Company’s financial statements and disclosures as its impact primarily related to immaterial short-term and long-term classifications on the Consolidated Balance Sheet and current and deferred income tax expense (benefit) classifications in the above table. Tax Act In fiscal 2018, the effective tax rate was impacted by the Tax Cuts and Jobs Act (the “Tax Act”), which was enacted on December 22, 2017. The Tax Act resulted in significant impacts to the Company’s accounting for income taxes with the most significant of these impacts relating to the reduction of the U.S. federal corporate income tax rate, a one-time transition tax on unrepatriated foreign earnings and full expensing of certain qualified depreciable assets placed in service after September 27, 2017 and before January 1, 2023. The Tax Act enacted a new U.S. federal corporate income tax rate of 21% that went into effect for the Company’s 2019 tax year and was prorated with the pre-December 22, 2017 U.S. federal corporate income tax rate of 35% for the Company’s 2018 tax year. This proration resulted in a blended U.S. federal corporate income tax rate of 24.5% for fiscal 2018. During the year ended September 30, 2018, the Company (i) remeasured its existing deferred tax assets and liabilities considering both the 2018 blended rate and the 21% rate for future periods and recorded a provisional tax benefit of $281.2 and (ii) calculated the one-time transition tax and recorded provisional tax expense of $10.3. Full expensing of certain depreciable assets will result in a temporary difference and will be analyzed as assets are placed in service. During the year ended September 30, 2019, in connection with preparing its fiscal 2018 corporate income tax returns, the Company recorded tax benefits related to the (i) re-measurement of its existing deferred tax assets and liabilities and (ii) adjustment to the one-time transition tax of $0.2 and $4.6, respectively. No income tax adjustments were made related to the Tax Act during the year ended September 30, 2020. The Tax Act subjects U.S. corporations to a tax on global low-taxed income, which the Company has elected to recognize in the period in which it is incurred. Unrecognized Tax Benefits The Company recognizes the tax benefit from uncertain tax positions only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities. The tax benefits recognized from such positions are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. To the extent the Company’s assessment of such tax positions changes, the change in estimate will be recorded in the period in which the determination is made. Unrecognized tax benefits activity for the years ended September 30, 2020, 2019 and 2018 is presented in the following table. September 30, 2020 2019 2018 Balance, beginning of year $ 8.6 $ 9.9 $ 8.6 Additions for tax positions taken in current year and acquisitions 1.7 0.1 2.0 Additions (reductions) for tax positions taken in prior years — 5.7 (0.1) Held for sale liabilities — — (0.6) Settlements with tax authorities/statute expirations (0.5) (7.1) — Balance, end of year $ 9.8 $ 8.6 $ 9.9 The amount of the net unrecognized tax benefits that, if recognized, would directly affect the effective tax rate was $9.6 at September 30, 2020. The Company believes that, due to expiring statutes of limitations and settlements with tax authorities, it is reasonably possible that the total unrecognized tax benefits may decrease up to approximately $1.8 within twelve months of the reporting date. The Company computes tax-related interest and penalties as the difference between the tax position recognized for financial reporting purposes and the amount previously taken on the Company’s tax returns and classifies these amounts as components of income tax (benefit) expense. The Company recorded (benefit) expense of zero, $(2.5) and $0.8 related to interest and penalties in the years ended September 30, 2020, 2019 and 2018, respectively. The Company had accrued interest and penalties of $1.0 and $1.0 at September 30, 2020 and 2019, respectively. The accrued interest and penalties are not included in the table above. U.S. federal, U.S. state and foreign jurisdiction income tax returns for the tax years ended September 30, 2015 through September 30, 2019 are generally open and subject to examination by the tax authorities in each respective jurisdiction. During the year ended September 30, 2019, the Internal Revenue Service initiated an examination of the Company’s 2015, 2016 and 2017 U.S. federal income tax returns. The Company does not expect the examination will have a material impact on its consolidated financial statements.

Earnings per Share

Earnings per Share	12 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Earnings per Share	EARNINGS PER SHARE Basic earnings per share is based on the average number of shares of common stock outstanding during the period. Diluted earnings per share is based on the average number of shares used for the basic earnings per share calculation, adjusted for the dilutive effect of stock options, stock appreciation rights, restricted stock units and performance-based restricted stock units using the “treasury stock” method. The impact of potentially dilutive convertible preferred stock is calculated using the “if-converted” method. In addition, “Net earnings for diluted earnings per share” in the table below has been adjusted for the Company’s share of BellRing’s consolidated net earnings for diluted earnings per share, to the extent it is dilutive. In the second quarter of fiscal 2019, the Company completed the redemption of its 2.5% Series C Cumulative Perpetual Convertible Preferred Stock (“Series C Preferred”). Substantially all of the 3.2 shares of Series C Preferred outstanding as of January 10, 2019, the date the Series C Preferred redemption was announced, were converted into 5.9 shares of the Company’s common stock pursuant to the conversion rights applicable to the Series C Preferred, and the remaining shares of Series C Preferred were redeemed. In the second quarter of fiscal 2018, the Company completed the redemption of its 3.75% Series B Cumulative Perpetual Convertible Preferred Stock (“Series B Preferred”). Substantially all of the 1.5 shares of Series B Preferred outstanding as of January 10, 2018, the date the redemption was announced, were converted into 3.1 shares of the Company’s common stock pursuant to the conversion rights applicable to the Series B Preferred, and the remaining shares of Series B Preferred were redeemed. For additional information on the Series C Preferred and Series B Preferred conversions, see Note 21. The following table sets forth the computation of basic and diluted earnings per share. Year ended September 30, 2020 2019 2018 Net earnings for basic earnings per share $ 0.8 $ 121.7 $ 457.3 Dilutive impact of BellRing net earnings — — — Dilutive preferred stock dividends — 3.0 10.0 Net earnings for diluted earnings per share $ 0.8 $ 124.7 $ 467.3 Weighted-average shares for basic earnings per share 68.9 70.8 66.6 Effect of dilutive securities: Stock options 0.6 1.6 1.8 Stock appreciation rights 0.1 0.1 0.1 Restricted stock units 0.4 0.5 0.4 Performance-based restricted stock units 0.1 — — Preferred shares conversion to common — 2.1 7.0 Total dilutive securities 1.2 4.3 9.3 Weighted-average shares for diluted earnings per share 70.1 75.1 75.9 Basic earnings per common share $ 0.01 $ 1.72 $ 6.87 Diluted earnings per common share $ 0.01 $ 1.66 $ 6.16 The following table details the securities that have been excluded from the calculation of weighted-average shares for diluted earnings per share as they were anti-dilutive. Year ended September 30, 2020 2019 2018 Stock options 0.1 0.1 0.6 Restricted stock units — — 0.1 Performance-based restricted stock units 0.1 — —

Supplemental Operations Stateme

Supplemental Operations Statement and Cash Flow Information	12 Months Ended
	Sep. 30, 2020
Supplemental Operations Statement and Cash Flow Information [Abstract]
Supplemental Operations Statement and Cash Flow Information	SUPPLEMENTAL OPERATIONS STATEMENT AND CASH FLOW INFORMATION Year Ended September 30, 2020 2019 2018 Advertising and promotion expenses (a) $ 146.0 $ 122.3 $ 153.4 Repair and maintenance expenses 140.0 156.9 149.1 Research and development expenses 28.5 25.0 25.1 Interest income (6.3) (7.9) (7.4) Interest paid 348.8 344.4 373.9 Income taxes paid 54.4 65.0 23.0 Accrued additions to property 29.8 24.7 30.4 (a) As a result of the adoption of ASU 2014-09, certain payments to customers totaling $23.7 in the year ended September 30, 2019 previously classified as advertising and promotion expenses were classified as net sales. For additional information, see Note 2.

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	12 Months Ended
	Sep. 30, 2020
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	SUPPLEMENTAL BALANCE SHEET INFORMATION September 30, 2020 2019 Receivables, net Trade $ 395.4 $ 407.8 Income tax receivable 26.6 21.9 Related party 3.2 5.1 Other 19.8 12.3 445.0 447.1 Allowance for doubtful accounts (3.4) (2.0) $ 441.6 $ 445.1 Inventories Raw materials and supplies $ 118.1 $ 99.4 Work in process 17.8 19.4 Finished products 429.4 425.4 Flocks 34.1 35.6 $ 599.4 $ 579.8 Other Assets Pension asset $ 159.0 $ 166.7 Operating ROU Assets 116.3 — Equity securities 27.9 — Other 25.8 38.8 $ 329.0 $ 205.5 Accounts Payable Trade $ 357.6 $ 349.6 Book cash overdrafts 0.7 35.1 Other 9.6 10.9 $ 367.9 $ 395.6 Other Current Liabilities Advertising and promotion $ 44.9 $ 45.2 Accrued interest 85.9 46.0 Accrued compensation 98.5 85.3 Hedging liabilities 187.9 87.6 Operating lease liabilities - current 23.6 — Accrued legal settlements 13.2 16.1 Accrued appraisal rights and related interest — 19.1 Other 87.6 94.5 $ 541.6 $ 393.8 Other Liabilities Pension and other postretirement benefit obligations $ 77.7 $ 66.0 Hedging liabilities - non-current 355.2 330.5 Accrued compensation - non-current 30.2 34.0 Operating lease liabilities - non-current 103.0 — Other 33.7 26.4 $ 599.8 $ 456.9

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts	12 Months Ended
	Sep. 30, 2020
Allowance for Doubtful Accounts [Abstract]
Allowance for Doubtful Accounts	ALLOWANCE FOR DOUBTFUL ACCOUNTS September 30, 2020 2019 2018 Balance, beginning of year $ 2.0 $ 2.3 $ 1.6 Provision charged to expense 3.3 0.1 0.1 Write-offs, less recoveries (1.9) (0.4) (1.2) Held for sale assets — — (0.5) Other (a) — — 2.3 Balance, end of year $ 3.4 $ 2.0 $ 2.3 (a) Other items are primarily related to acquisitions.

Derivative Financial Instrument

Derivative Financial Instruments and Hedging	12 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Hedging	DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING In the ordinary course of business, the Company is exposed to commodity price risks relating to the purchases of raw materials, energy and fuel and supplies, interest rate risks relating to floating rate debt and foreign currency exchange rate risks. The Company utilizes derivative financial instruments, including (but not limited to) futures contracts, option contracts, forward contracts and swaps, to manage certain of these exposures by hedging when it is practical to do so. The Company does not hold or issue financial instruments for speculative or trading purposes. At September 30, 2020, the Company’s derivative instruments, none of which were designated as hedging instruments under ASC Topic 815, “Derivatives and Hedging,” consisted of: • commodity and energy futures, swaps and option contracts which relate to inputs that generally will be utilized within the next two years; • foreign currency forward contracts maturing in the next year that have the effect of hedging currency fluctuations between the Euro and the Pound Sterling and the U.S. Dollar and the Pound Sterling; • interest rate swaps that have the effect of hedging interest payments on debt expected to be issued but not yet priced, including: • pay-fixed, receive-variable interest rate swaps maturing in May 2021 and May 2024 that require monthly settlements; • rate-lock interest rate swaps that require nine lump sum settlements with the first settlement occurring in July 2021 and the last in July 2026; and • interest rate swaps that mature in July 2021 and give the Company the option of pay-variable, receive-fixed lump sum settlements; and • pay-fixed, receive-variable interest rate swaps maturing in December 2022 that require monthly settlements and have the effect of hedging forecasted interest payments on BellRing’s variable rate debt. Interest rate swaps Fiscal 2020 In the first quarter of fiscal 2020, contemporaneously with the repayment of its term loan, the Company changed the designation of one of its interest rate swap contracts from a cash flow hedge to a non-designated hedging instrument. In connection with the de-designation, the Company reclassified losses previously recorded in accumulated OCI of $7.2 to “Interest expense, net” in the Consolidated Statement of Operations for the year ended September 30, 2020. As of April 1, 2020, the Company changed the designation of its interest rate swap contracts that are used as hedges of forecasted interest payments on BellRing’s variable rate debt from cash flow hedges to non-designated hedging instruments as the swaps were no longer effective (as defined by ASC Topic 815). In connection with the de-designation, the Company started reclassifying losses previously recorded in accumulated OCI to “Interest expense, net” in the Consolidated Statements of Operations on a straight-line basis over the term of BellRing’s variable rate debt. Mark-to-market adjustments related to these swaps also will be included in “Interest expense, net” in the Consolidated Statements of Operations. At September 30, 2020, the remaining net loss before taxes to be amortized was $9.4. Fiscal 2019 In the first quarter of fiscal 2019, the Company terminated $800.0 notional value of its interest rate swap contracts that were designated as hedging instruments. In connection with the interest rate swap terminations, the Company received cash proceeds of $29.8, and reclassified previously recorded gains from accumulated OCI to “Interest expense, net” in the Consolidated Statement of Operations for the year ended September 30, 2019. Cross-currency swaps The Company terminated $448.7 and $214.2 notional value of its cross-currency swap contracts that were designated as hedging instruments during the second quarter of fiscal 2020 and the first quarter of fiscal 2019, respectively. In connection with these terminations, the Company received cash proceeds of $50.3 during the year ended September 30, 2020 and $26.2 during the year ended September 30, 2019, both of which were recorded to accumulated OCI. Reclassification of amounts recorded in accumulated OCI into earnings will only occur in the event U.K.-based operations are substantially liquidated. Foreign currency forward contracts In the second quarter of fiscal 2018, the Company changed the designation of its foreign currency forward contracts from a cash flow hedge to a non-designated hedging instrument. In connection with the new designation, the Company reclassified gains previously recorded in accumulated OCI of $1.8, of which $1.3 was reclassified to “Selling, general and administrative expenses” in the Consolidated Statement of Operations for the year ended September 30, 2018 and $0.5 was reclassified to “Property, net” on the Consolidated Balance Sheet as of September 30, 2018. The following table shows the notional amounts of derivative instruments held. September 30, September 30, Not designated as hedging instruments under ASC Topic 815: Commodity contracts $ 24.7 $ 47.1 Energy contracts 87.1 39.8 Foreign exchange contracts - Forward contracts 28.9 — Interest rate swap 621.7 73.1 Interest rate swaps - Rate-lock swaps 1,666.0 1,531.0 Interest rate swaps - Options 433.3 — Designated as hedging instruments under ASC Topic 815: Foreign exchange contracts - Cross-currency swaps — 448.7 Interest rate swap — 200.0 The following table presents the balance sheet location and fair value of the Company’s derivative instruments, along with the portion designated as hedging instruments under ASC Topic 815. The Company does not offset derivative assets and liabilities within the Consolidated Balance Sheets. Fair Value Portion Designated as Hedging Instruments Balance Sheet Location September 30, September 30, September 30, September 30, Asset Derivatives: Commodity contracts Prepaid expenses and other current assets $ 5.0 $ 1.9 $ — $ — Energy contracts Prepaid expenses and other current assets 1.8 0.7 — — Commodity contracts Other assets 0.1 0.1 — — Energy contracts Other assets 0.9 — — — Foreign exchange contracts Prepaid expenses and other current assets 0.1 1.3 — 1.3 Foreign exchange contracts Other assets — 19.2 — 19.2 Interest rate swaps Prepaid expenses and other current assets 6.8 — — — $ 14.7 $ 23.2 $ — $ 20.5 Liability Derivatives: Commodity contracts Other current liabilities $ 1.4 $ 1.0 $ — $ — Energy contracts Other current liabilities 10.1 1.5 — — Energy contracts Other liabilities 3.9 0.1 — — Interest rate swaps Other current liabilities 176.4 85.1 — 1.6 Interest rate swaps Other liabilities 351.3 330.4 — 6.2 $ 543.1 $ 418.1 $ — $ 7.8 The following tables present the effects of the Company’s derivative instruments on the Company’s Consolidated Statements of Operations and Consolidated Statements of Comprehensive Income. Derivatives Not Designated as Hedging Instruments Statement of Operations Location Loss (Gain) Recognized in Statement of Operations 2020 2019 2018 Commodity contracts Cost of goods sold $ 3.8 $ 2.8 $ 4.0 Energy contracts Cost of goods sold 21.6 5.0 (6.4) Foreign exchange contracts Selling, general and administrative expenses (0.1) — 1.5 Interest rate swaps Interest expense, net 3.0 — — Interest rate swaps Expense (income) on swaps, net 187.1 306.6 (95.6) Derivatives Designated as Hedging Instruments Loss (Gain) Recognized in OCI including NCI Loss (Gain) Reclassified from Accumulated OCI including NCI into Earnings (a) Statement of Operations Location 2020 2019 2018 2020 2019 2018 Foreign exchange contracts $ — $ — $ (0.2) $ — $ — $ (1.3) Selling, general and administrative expenses Interest rate swaps 9.7 13.8 (44.2) 8.2 (31.0) (2.3) Interest expense, net Cross-currency swaps (32.2) (54.3) (27.8) — — — Expense (income) on swaps, net (a) For the year ended September 30, 2020, this amount includes the reclassification of previously unrealized net losses on interest rate swaps that were de-designated as hedging instruments in the first quarter of fiscal 2020, as well as the amortization of previously unrealized losses on BellRing’s interest rate swaps that were de-designated as hedging instruments as of April 1, 2020. The following table presents the components of the Company’s net hedging losses (gains) on interest rate swaps, which are included in “Interest expense, net” and “Expense on swaps, net” in the Consolidated Statements of Operations. Year Ended Statement of Operations Location Mark-to-Market Loss (a) Cash Settlements Paid (Received), Net (b) Net Loss Reclassified from Accumulated OCI including NCI (c) Interest expense, net $ (0.2) $ 1.8 $ 8.4 Expense on swaps, net 117.4 69.7 — 2020 Total $ 117.2 $ 71.5 $ 8.4 Interest expense, net $ — $ (31.0) $ — Expense on swaps, net 293.1 13.5 — 2019 Total $ 293.1 $ (17.5) $ — Interest expense, net $ — $ (2.3) $ — Expense on swaps, net (96.7) 1.1 — 2018 Total $ (96.7) $ (1.2) $ — (a) Includes non-cash adjustments related to interest rate swaps that were not designated as hedging instruments. (b) Includes cash settlements recognized in earnings related to interest rate swaps that were not designated as hedging instruments and cash settlements reclassified from accumulated OCI into earnings related to interest rate swaps that had been previously designated as hedging instruments. (c) Includes the reclassification of previously unrealized losses on interest rate swaps that were de-designated as hedging instruments, as well as the amortization of previously unrealized losses on BellRing’s interest rate swaps over the term of the related debt that were de-designated as hedging instruments. Accumulated OCI, including amounts reported as NCI, included a $90.2 net gain on hedging instruments before taxes ($67.9 after taxes) at September 30, 2020, compared to a $59.5 net gain before taxes ($44.5 after taxes) at September 30, 2019. Approximately $2.3 of the net hedging losses reported in accumulated OCI at September 30, 2020 are expected to be reclassified into earnings within the next 12 months. Accumulated OCI included settlements of and previously unrealized gains on cross-currency swaps of $99.5 and $36.5 at September 30, 2020 and 2019, respectively. In connection with the settlements and terminations of cross-currency swaps, the Company recognized gains in accumulated OCI of $63.0, $31.7 and $4.8 during the years ended September 30, 2020, 2019 and 2018, respectively. Reclassification of amounts recorded in accumulated OCI into earnings will only occur in the event all U.K.-based operations are substantially liquidated. At September 30, 2020 and 2019, the Company had pledged collateral of $5.3 and $3.7, respectively, related to its commodity and energy contracts. These amounts were classified as “Restricted cash” on the Consolidated Balance Sheets.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The following table presents the assets and liabilities measured at fair value on a recurring basis and the basis for that measurement according to the levels in the fair value hierarchy in ASC Topic 820, “Fair Value Measurement.” September 30, 2020 September 30, 2019 Total Level 1 Level 2 Total Level 1 Level 2 Assets Deferred compensation investment $ 12.8 $ 12.8 $ — $ 11.2 $ 11.2 $ — Derivative assets 14.7 — 14.7 23.2 — 23.2 Equity securities 27.9 27.9 — — — — $ 55.4 $ 40.7 $ 14.7 $ 34.4 $ 11.2 $ 23.2 Liabilities Deferred compensation liabilities $ 29.7 $ — $ 29.7 $ 31.0 $ — $ 31.0 Derivative liabilities 543.1 — 543.1 418.1 — 418.1 $ 572.8 $ — $ 572.8 $ 449.1 $ — $ 449.1 The deferred compensation investments are primarily invested in mutual funds, and the fair value is measured using the market approach. These investments are in the same funds, and are purchased in substantially the same amounts, as the participants’ selected investment options (excluding Post common stock equivalents), which represent the underlying liabilities to participants in the Company’s deferred compensation plans. Deferred compensation liabilities are recorded at amounts due to participants in cash, based on the fair value of participants’ selected investment options (excluding certain Post common stock equivalents to be distributed in shares) using the market approach. The Company utilizes the income approach to measure fair value for its commodity and energy derivatives. The income approach uses pricing models that rely on market observable inputs such as yield curves and forward prices. Foreign exchange contracts are valued using the spot rate less the forward rate multiplied by the notional amount. The Company’s calculation of the fair value of interest rate swaps is derived from a discounted cash flow analysis based on the terms of the contract and the interest rate curve. Refer to Note 14 for the classification of changes in fair value of derivative assets and liabilities measured at fair value on a recurring basis within the Consolidated Statements of Operations. The Company uses the market approach to measure the fair value of its equity securities. The Company’s financial assets and liabilities also include cash and cash equivalents, receivables and accounts payable for which the carrying value approximates fair value due to their short maturities (less than 12 months). The Company does not record its current portion of long-term debt and long-term debt at fair value on the Consolidated Balance Sheets. The fair value of the outstanding borrowings under the municipal bond and BellRing’s Revolving Credit Facility (as defined in Note 17) as of September 30, 2020 approximated its carrying value. Based on current market rates, the fair value of the Company’s debt, excluding outstanding borrowings under the municipal bond and BellRing’s Revolving Credit Facility (both of which are categorized as Level 2), was $7,277.8 and $7,412.0 as of September 30, 2020 and 2019, respectively. Certain assets and liabilities, including long-lived assets, goodwill, indefinite-lived intangibles and assets held for sale, are measured at fair value on a non-recurring basis. In the year ended September 30, 2020, no impairment charge was recorded for goodwill or definite-lived or indefinite-lived intangibles. In the year ended September 30, 2019, the Company recorded goodwill and definite-lived intangible asset impairment charges of $63.3. In the year ended September 30, 2018, the Company recorded indefinite-lived intangible asset impairment charges of $124.9. These losses were recorded as “Impairment of goodwill and other intangible assets” in the Consolidated Statements of Operations. For additional information on other intangible assets and goodwill, see Note 2 and Note 7, respectively. There were no other fair value measurement losses recognized during the years ended September 30, 2020, 2019 or 2018. At September 30, 2020, the Company had land and buildings classified as assets held for sale related to the closures of the Company’s Clinton Plant, Asheboro Facility and Corby Facility. At September 30, 2019, the Company had land and buildings classified as assets held for sale related to the closures of the Company’s Clinton Plant and Asheboro Facility. The Company sold a portion of the Clinton Plant in March 2020. The Clinton Plant and the Asheboro Facility are both reported in the Company’s Post Consumer Brands segment, and the Corby Facility is reported in the Company’s Weetabix segment. In the year ended September 30, 2020, the book value of the land related to the Corby Facility was lower than fair value; therefore, no fair value adjustment was recorded to the assets that were classified as held for sale. On October 1, 2018, the Company completed the 8th Avenue Transactions, and in November 2018, the Post Consumer Brands cereal warehouse was sold in connection with the closure of its Clinton Facility. For additional information on assets and liabilities held for sale, see Note 6. The fair value of assets and liabilities held for sale was measured on a non-recurring basis based on the lower of book value or third party data. When applicable, the fair value is adjusted to reflect an offer to purchase the assets and liabilities. The fair value measurement was categorized as Level 3, as the fair values utilize significant unobservable inputs. The following table summarizes the Level 3 activity. Balance, September 30, 2018 $ 290.9 Gains related to assets and liabilities held for sale 124.6 Proceeds from the sale of assets and liabilities held for sale (276.6) Investment in 8th Avenue, working capital and other adjustments (138.9) Transfers of assets into held for sale 9.9 Balance, September 30, 2019 $ 9.9 Losses related to assets held for sale (2.7) Proceeds from the sale of assets held for sale (2.4) Transfer of assets into held for sale 2.5 Balance, September 30, 2020 $ 7.3

Leases

Leases	12 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	LEASES In conjunction with the adoption of ASUs 2016-02 and 2018-11 (see Note 3), the Company updated its policy for recognizing leases under ASC Topic 842. The Company assessed the impact of these ASUs by reviewing its lease portfolio, implementing lease accounting software, developing related business processes and implementing internal controls. A summary of the updated policy is included below. Prior to October 1, 2019, the Company accounted for leases under ASC Topic 840, “Leases.” Lease Portfolio The Company leases office space, certain warehouses and equipment primarily through operating lease agreements. The Company has no material finance lease agreements. Leases have remaining terms which range from 1 to 56 years and most leases provide the Company with the option to exercise one or more renewal terms. Lease Policy The Company determines if an arrangement is a lease at its inception. When the arrangements include lease and non-lease components, the Company accounts for them as a single lease component. Leases with an initial term of less than 12 months are not reported on the balance sheet, but rather are recognized as lease expense on a straight-line basis over the lease term. Arrangements may include options to extend or terminate the lease arrangement. These options are included in the lease term used to establish ROU assets and lease liabilities when it is reasonably certain they will be exercised. The Company will reassess expected lease terms based on changes in circumstances that indicate options may be more or less likely to be exercised. The Company has certain lease arrangements that include variable rental payments. The future variability of these payments and adjustments are unknown and therefore are not included in minimum rental payments used to determine ROU assets and lease liabilities. The Company has lease arrangements where it makes separate payments to the lessor based on the lessor’s common area maintenance expenses, property and casualty insurance costs, property taxes assessed on the property and other variable expenses. As the Company has elected the practical expedient not to separate lease and non-lease components, these variable amounts are captured in operating lease expense in the period in which they are incurred. Variable rental payments are recognized in the period in which their associated obligation is incurred. As most of the Company’s lease arrangements do not provide an implicit interest rate, an incremental borrowing rate (“IBR”) is applied in determining the present value of future payments. The Company’s IBR is selected based upon information available at the lease commencement date. ROU assets are recorded as “Other assets” and lease liabilities are recorded as “Other current liabilities” and “Other liabilities” on the Consolidated Balance Sheet. Operating lease expense is recognized on a straight-line basis over the lease term and is included in either “Cost of goods sold” or “Selling, general and administrative expenses” in the Consolidated Statements of Operations. Costs associated with finance leases and lease income do not have a material impact on the Company’s financial statements. Impact of Adoption The Company utilized the cumulative effect adjustment method of adoption and, accordingly, recorded ROU assets and lease liabilities of $158.1 and $168.2, respectively, on the balance sheet at October 1, 2019. The Company elected the following practical expedients in accordance with ASC Topic 842: • Reassessment elections — The Company elected the package of practical expedients, and did not reassess whether any existing contracts are or contain a lease, provided a lease analysis was conducted under ASC Topic 840. To the extent leases were identified under ASC Topic 840, the Company did not reassess the classification of those leases. Additionally, to the extent initial direct costs were capitalized under ASC Topic 840 and are not amortized as a result of the implementation of ASC Topic 842, they were not reassessed. • Short-term lease election — ASC Topic 842 allows lessees an option to not recognize ROU assets and lease liabilities arising from short-term leases. A short-term lease is defined as a lease with an initial term of 12 months or less. The Company elected to not recognize short-term leases as ROU assets and lease liabilities on the balance sheet. All short-term leases which are not included on the Company’s balance sheet will be recognized within lease expense. Leases that have an initial term of 12 months or less with an option for renewal will need to be assessed in order to determine if the lease qualifies for the short-term lease exception. If the option is reasonably certain to be exercised, the lease does not qualify as a short-term lease. • Lease vs non-lease components — The Company elected to combine lease and non-lease components as a single component and the total consideration for the arrangements was accounted for as a lease. The following table presents the balance sheet location of the Company’s operating leases. September 30, 2020 ROU assets: Other assets $ 116.3 Lease liabilities: Other current liabilities $ 23.6 Other liabilities 103.0 Total lease liabilities $ 126.6 The following table presents maturities of the Company’s operating lease liabilities as of September 30, 2020, presented under ASC Topic 842. September 30, 2020 Fiscal 2021 $ 28.7 Fiscal 2022 27.7 Fiscal 2023 24.4 Fiscal 2024 17.7 Fiscal 2025 11.9 Thereafter 39.9 Total future minimum payments $ 150.3 Less: Implied interest 23.7 Total lease liabilities $ 126.6 The following table presents future minimum rental payments under the Company’s noncancelable operating lease agreements as of September 30, 2019, presented under ASC Topic 840. September 30, Fiscal 2020 $ 28.3 Fiscal 2021 29.0 Fiscal 2022 28.1 Fiscal 2023 25.4 Fiscal 2024 19.2 Thereafter 77.3 Total future minimum payments (a) $ 207.3 (a) Future minimum payments as of September 30, 2019 included $36.0 related to a real estate lease, consisting of land and a building, that was purchased by the Company in December 2019 and the Company de-recognized both a ROU asset and lease liability of $23.1 and recognized the assets as property on the balance sheet. As reported under ASC Topic 842, operating lease expense for the year ended September 30, 2020 was $42.0. Of the total operating lease expense incurred during the year ended September 30, 2020, $5.1 related to variable lease costs and $7.5 related to short-term lease costs. As reported under ASC Topic 840, rent expense during the years ended September 30, 2019 and 2018 was $40.1 and $41.3, respectively. Operating cash flows for amounts included in the measurement of the Company’s operating lease liabilities for the year ended September 30, 2020 were $29.6. ROU assets obtained in exchange for operating lease liabilities during the year ended September 30, 2020 were $5.6. The weighted average remaining lease term of the Company’s operating leases as of September 30, 2020 was approximately 7 years and the weighted average IBR was 4.4% as of September 30, 2020.

Long Term Debt

Long Term Debt	12 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Long-term Debt	LONG-TERM DEBT Long-term debt as of the dates indicated consists of the following: September 30, 2020 2019 4.625% Senior Notes maturing April 2030 $ 1,650.0 $ — 5.50% Senior Notes maturing December 2029 750.0 750.0 5.625% Senior Notes maturing January 2028 940.9 940.9 5.50% Senior Notes maturing March 2025 — 1,000.0 5.75% Senior Notes maturing March 2027 1,299.3 1,299.3 5.00% Senior Notes maturing August 2026 1,697.3 1,697.3 8.00% Senior Notes maturing July 2025 — 122.2 Term Loan — 1,309.5 BellRing Term B Facility 673.7 — BellRing Revolving Credit Facility 30.0 — Municipal bond 8.5 — Capital lease — 0.1 7,049.7 7,119.3 Less: Current Portion 64.9 13.5 Debt issuance costs, net 62.6 69.0 Plus: Unamortized premium 36.8 29.2 Total long-term debt $ 6,959.0 $ 7,066.0 Senior Notes On August 18, 2015, the Company issued $400.0 principal value of 8.00% senior notes maturing in July 2025. The 8.00% senior notes were issued at par, and the Company received $396.0 after paying related fees of $4.0, which were deferred and were being amortized to interest expense over the term of the notes. On August 3, 2016, the Company issued $1,750.0 principal value of 5.00% senior notes maturing in August 2026. The 5.00% senior notes were issued at par, and the Company received $1,725.7 after paying related fees of $24.3, which were deferred and are being amortized to interest expense over the term of the notes. Interest payments on the 5.00% senior notes are due semi-annually each February 15 and August 15. On February 8, 2019, the Company received consents (the “Requisite Consents”) from holders of a majority of the aggregate principal amount of its outstanding 5.00% senior notes to approve amendments to the indenture relating to the 5.00% senior notes (the “Indenture”). Following receipt of the Requisite Consents, the Company, its subsidiary guarantors and the trustee for the Indenture executed a supplemental indenture to give effect to the amendments. The supplemental indenture more closely aligned certain provisions of the Indenture with the comparable provisions included in the indentures for the Company’s other senior notes, specifically to (i) add an exception to the restricted payments covenant in the Indenture and (ii) revise the “Permitted Investments” definition in the Indenture to add an additional category of Permitted Investments under the Indenture. In connection with the required consents, the Company incurred $8.4 of debt modification costs during the year ended September 30, 2019, which were deferred and will be amortized to interest expense over the remaining term of the 5.00% senior notes, and recorded expense of $1.3 in the year ended September 30, 2019, which was included in “Selling, general and administrative expenses” in the Consolidated Statement of Operations. On February 14, 2017, the Company issued $1,000.0 principal value of 5.50% senior notes maturing in March 2025 and $750.0 principal value of 5.75% senior notes maturing in March 2027. The 5.50% senior notes maturing in March 2025 and the 5.75% senior notes were each issued at par, and the Company received $1,725.4 after paying related fees of $24.6, which were deferred and are being amortized to interest expense over the term of the notes. On August 10, 2017, the Company issued an additional $750.0 principal value of 5.75% senior notes maturing in March 2027. The additional 5.75% senior notes were issued at 105.5% of par value, and the Company received $784.0 after paying related fees of $7.2, which were deferred and are being amortized to interest expense over the term of the 5.75% senior notes. The premium related to the 5.75% senior notes was recorded as an unamortized premium, and is being amortized as a reduction to interest expense over the term of the notes. Interest payments on the 5.75% senior notes are due semi-annually each March 1 and September 1. On December 1, 2017, the Company issued $1,000.0 principal value of 5.625% senior notes maturing in January 2028. The 5.625% senior notes were issued at par, and the Company received $990.6 after paying related fees of $9.4, which were deferred and are being amortized to interest expense over the term of the notes. Interest payments on the 5.625% senior notes are due semi-annually each January 15 and July 15. On July 3, 2019, the Company issued $750.0 principal value of 5.50% senior notes maturing in December 2029. The 5.50% senior notes maturing in December 2029 were issued at par, and the Company received $743.0 after incurring investment banking and other fees and expenses of $7.0, which were deferred and are being amortized to interest expense over the term of the notes. Interest payments on the 5.50% senior notes maturing in December 2029 are due semi-annually each June 15 and December 15. On February 26, 2020, the Company issued $1,250.0 principal value of 4.625% senior notes maturing in April 2030. The 4.625% senior notes were issued at par, and the Company received $1,241.0 after incurring investment banking and other fees and expenses of $9.0, which were deferred and are being amortized to interest expense over the term of the notes. Interest payments on the 4.625% senior notes are due semi-annually each April 15 and October 15, beginning on October 15, 2020. On August 14, 2020, the Company issued an additional $400.0 principal value of 4.625% senior notes maturing in April 2030. The additional 4.625% senior notes were issued at a price of 105.5% of the par value and the Company received $417.5 after incurring investment banking and other fees and expenses of $4.5 which were deferred and are being amortized to interest expense over the term of the notes. The premium related to the 4.625% senior notes was recorded as an unamortized premium, and is being amortized as a reduction of interest expense over the term of the notes. All of the Company’s senior notes are fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by each of the Company’s existing and future domestic subsidiaries, other than immaterial subsidiaries, receivables finance subsidiaries and subsidiaries the Company designated as unrestricted subsidiaries, which such unrestricted subsidiaries includes 8th Avenue and its subsidiaries and BellRing Brands, Inc. and its subsidiaries. These guarantees are subject to release in certain circumstances. Credit Agreement On March 28, 2017, the Company entered into an amended and restated credit agreement (the “First AR Credit Agreement”). On March 18, 2020, the Company entered into a second amended and restated credit agreement (the “Second AR Credit Agreement”). The Second AR Credit Agreement provides for a revolving credit facility in an aggregate principal amount of $750.0 (the “Revolving Credit Facility”), with the commitments thereunder to be made available to the Company in U.S. Dollars, Canadian Dollars, Euros and Pounds Sterling. Letters of credit are available under the Second AR Credit Agreement in an aggregate amount of up to $75.0 . The Company incurred $3.6 of issuance costs in connection with entering into the Second AR Credit Agreement, which were deferred and are being amortized to interest expense over the term of the Second AR Credit Agreement. Additionally, the Company recorded write-offs of debt issuance costs of $0.8 in the year ended September 30, 2020, which were included in “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations. During the year ended September 30, 2020, the Company borrowed $500.0 under the Revolving Credit Facility and repaid $500.0 on the Revolving Credit Facility. The proceeds under the Revolving Credit Facility may be used for working capital, general corporate or other purposes as permitted by the Revolving Credit Facility. The Revolving Credit Facility has outstanding letters of credit of $18.8 , which reduced the available borrowing capacity under the Revolving Credit Facility to $731.2 at September 30, 2020 . Any outstanding amounts under the Revolving Credit Facility must be repaid on or before March 18, 2025. The Second AR Credit Agreement provides for potential incremental revolving and term facilities at the request of the Company and at the discretion of the lenders or other persons providing such incremental facilities, in each case on terms to be determined, and also permits the Company to incur other secured or unsecured debt, in all cases subject to conditions and limitations on the amount as specified in the Second AR Credit Agreement. The Second AR Credit Agreement permits the Company to designate certain of its subsidiaries as unrestricted subsidiaries and once so designated, permits the disposition of (and authorizes the release of liens on) the assets of, and the equity interests in, such unrestricted subsidiaries and permits the release of such unrestricted subsidiaries as guarantors under the Second AR Credit Agreement. The Company’s obligations under the Second AR Credit Agreement are unconditionally guaranteed by its existing and subsequently acquired or organized direct and indirect domestic subsidiaries (other than immaterial domestic subsidiaries, certain excluded subsidiaries and subsidiaries the Company designates as unrestricted subsidiaries, which include 8th Avenue and its subsidiaries and BellRing Brands, Inc. and its subsidiaries) and are secured by security interests in substantially all of the Company’s assets and the assets of its subsidiary guarantors, but excluding, in each case, real property. Borrowings under the Revolving Credit Facility bear interest, at the option of the Company, at an annual rate equal to either (a) the Eurodollar rate or (b) the base rate determined by reference to the highest of (i) the prime rate, (ii) the federal funds rate plus 0.50% per annum and (iii) the one-month Eurodollar rate plus 1.00% per annum, in each case plus an applicable margin, which initially were 1.50% for Eurodollar rate-based loans and 0.50% for base rate-based loans, and thereafter, will be determined by reference to the secured net leverage ratio (as defined in the Second AR Credit Agreement), with the applicable margin for Eurodollar rate loans and base rate loans being (i) 2.00% and 1.00%, respectively, if the secured net leverage ratio is greater than or equal to 3.00:1.00, (ii) 1.75% and 0.75%, respectively, if the secured net leverage ratio is less than 3.00:1.00 and greater than or equal to 1.50:1.00 or (iii) 1.50% and 0.50%, respectively, if the secured net leverage ratio is less than 1.50:1.00. Commitment fees on the daily unused amount of commitments under the Revolving Credit Facility initially accrued at the rate of 0.25%, and thereafter, will accrue at a rate of 0.375% if the Company’s secured net leverage ratio is greater than 3.00:1.00, and will accrue at a rate of 0.25% if the Company’s secured net leverage ratio is less than or equal to 3.00:1.00. The Second AR Credit Agreement provides for customary events of default, including material breach of representations and warranties, failure to make required payments, failure to comply with certain agreements or covenants, failure to pay or default under certain other indebtedness in excess of $100.0, certain events of bankruptcy and insolvency, inability to pay debts, the occurrence of one or more unstayed or undischarged judgments in excess of $100.0, attachments issued against all or any material part of the Company’s property, certain events under the Employee Retirement Income Security Act of 1974 (“ERISA”), a change of control (as defined in the Second AR Credit Agreement), the invalidity of any loan document and the failure of the collateral documents to create a valid and perfected first priority lien (subject to certain permitted liens). Upon the occurrence and during the continuance of an event of default, the maturity of the loans under the Second AR Credit Agreement may accelerate and the agent and lenders under the Second AR Credit Agreement may exercise other rights and remedies available at law or under the loan documents, including with respect to the collateral and guarantees of the Company’s obligations under the Second AR Credit Agreement. 2020 Bridge Loan On October 11, 2019, in connection with the IPO and the formation transactions, the Company entered into a $1,225.0 bridge facility agreement (the “2020 Bridge Loan Facility”) and borrowed $1,225.0 under the 2020 Bridge Loan Facility (the “2020 Bridge Loan”). On October 21, 2019, BellRing entered into a borrower assignment and assumption agreement with the Company and the administrative agent under the 2020 Bridge Loan Facility, under which BellRing became the borrower under the 2020 Bridge Loan and assumed all interest of $2.2 thereunder, and the Company and its subsidiary guarantors (other than BellRing and its domestic subsidiaries) were released from all material obligations thereunder. The Company retained the net cash proceeds of the 2020 Bridge Loan, and following the assumption by BellRing of the 2020 Bridge Loan Facility, used the cash proceeds of the 2020 Bridge Loan to repay a portion of the $1,309.5 outstanding principal balance of its Term Loan (as defined below). The domestic subsidiaries of BellRing continued to guarantee the 2020 Bridge Loan, and BellRing’s obligations under the 2020 Bridge Loan became secured by a first priority security interest in substantially all of the assets (other than real property) of BellRing and in substantially all of the assets of its subsidiary guarantors. On October 21, 2019, the 2020 Bridge Loan was repaid in full by BellRing. In connection with the 2020 Bridge Loan Facility, the Company incurred issuance costs of $19.1, of which $15.3 were refunded to the Company at the closing of the IPO on October 21, 2019, and the remaining $3.8 of issuance costs were written off and included in “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations for the year ended September 30, 2020. 2018 Bridge Loan On September 24, 2018, in connection with the 8th Avenue Transactions (see Note 6), the Company entered into a $625.0 bridge facility agreement (the “2018 Bridge Loan Facility”) and borrowed $625.0 under the Bridge Loan Facility (the 2018 Bridge Loan, as defined in Note 6). The 2018 Bridge Loan bore interest at a rate per annum equal to the Eurodollar Rate (as such term is defined in the 2018 Bridge Loan Facility) plus 450 basis points. In connection with the 2018 Bridge Loan Facility, the Company incurred issuance costs of $10.4, of which $7.8 were refunded to the Company at the closing of the 8th Avenue Transactions on October 1, 2018, and the remaining $2.6 of issuance costs were written off and included in “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations for the year ended September 30, 2019 (see Note 6). Upon the closing of the 8th Avenue Transactions on October 1, 2018, the 2018 Bridge Loan was assumed by 8th Avenue and the Company (other than 8th Avenue and its subsidiaries) was released from its repayment obligations thereunder while retaining the proceeds from the 2018 Bridge Loan. Term Loans On May 24, 2017, the Company entered into a Joinder Agreement No. 1 (“Joinder No. 1”). Joinder No.1 provided for an incremental term loan of $1,200.0 (the “Joinder No. 1 Term Loan”) under the First AR Credit Agreement. Pursuant to Joinder No. 1, the Company borrowed $1,200.0 and used a portion of the proceeds to fund payments to holders of the Company’s then outstanding 8.00% senior notes and then outstanding 7.75% senior notes who tendered their notes in connection with the Company’s tender offer and whose notes were accepted for purchase and to pay related fees and expenses. On June 29, 2017, the Company entered into a Joinder Agreement No. 2 (“Joinder No. 2”). Joinder No. 2 provided for an incremental term loan of $1,000.0 (the “ Joinder No. 2 Term Loan”) under the First AR Credit Agreement. Pursuant to Joinder No. 2, the Company borrowed $1,000.0 and used the proceeds, together with cash on hand, to finance its fiscal 2017 acquisition of Latimer Newco 2 Limited (“Latimer”), and all of Latimer’s direct and indirect subsidiaries, including Weetabix Limited. The Joinder No. 2 Term Loan was combined with the outstanding amounts under the Joinder No.1 Term Loan (collectively the “Term Loan”). On March 8, 2018, the Company entered into a second amendment to the First AR Credit Agreement (the “Second Amendment”). Under the Second Amendment, the interest rate margin for the Term Loan was reduced by 25 basis points such that a Term Loan that is a Eurodollar Rate Loan accrues interest at the Eurodollar Rate plus 2.00% per annum, and a Term Loan that is a Base Rate Loan accrues interest at the Base Rate plus 1.00% per annum (as such terms were defined in the First AR Credit Agreement). All other material provisions of the Credit Agreement remained unchanged. The interest rate on the Term Loan was 4.04% at September 30, 2019. Municipal Bond In connection with the ongoing construction of a filtration system at the Company’s potato plant in Chaska, Minnesota, the Company continues to incur debt that guarantees the repayment of certain industrial revenue bonds used to finance the construction of the project. During the year ended September 30, 2020, the Company received $2.2 in proceeds related to the municipal bond and repaid $1.1 related to the municipal bond. Principal payments are due annually on March 1, and interest payments are due semi-annually each March 1 and September 1. The debt matures on March 1, 2028. BellRing’s Credit Agreement and Senior Debt Facilities On October 21, 2019, BellRing entered into a credit agreement (the “BellRing Credit Agreement”), which provides for a term B loan facility in an aggregate principal amount of $700.0 (the “BellRing Term B Facility”) and a revolving credit facility in an aggregate principal amount of $200.0 (the “BellRing Revolving Credit Facility”), with the commitments under the BellRing Revolving Credit Facility to be made available to BellRing in U.S. Dollars, Euros and Pounds Sterling. Letters of credit are available under the BellRing Credit Agreement in an aggregate amount of up to $20.0. The outstanding amounts under the BellRing Revolving Credit Facility and BellRing Term B Facility must be repaid on or before October 21, 2024. On October 21, 2019, BellRing borrowed the full amount under the BellRing Term B Facility and $100.0 under the BellRing Revolving Credit Facility. The BellRing Term B Facility was issued at 98.0% of par and BellRing received $776.4 from the BellRing Term B Facility and BellRing Revolving Credit Facility after accounting for the original issue discount of $14.0 and paying investment banking and other fees of $9.6, which were deferred and are being amortized to interest expense over the terms of the loans. BellRing used the proceeds, together with the net proceeds of the IPO that were contributed to it by BellRing Brands, Inc., (i) to repay in full the $1,225.0 of borrowings under the 2020 Bridge Loan and all interest thereunder and related costs and expenses, (ii) to pay directly, or reimburse the Company for, as applicable, all fees and expenses incurred by BellRing Brands, Inc., BellRing or the Company in connection with the IPO and the formation transactions, (iii) to reimburse the Company for the amount of cash on BellRing’s balance sheet immediately prior to the completion of the IPO and (iv) for general corporate and working capital purposes, as well as to repay $20.0 of outstanding borrowings under the BellRing Revolving Credit Facility. During the year ended September 30, 2020, BellRing borrowed $195.0 under the BellRing Revolving Credit Facility and repaid $165.0 on the BellRing Revolving Credit Facility. As of September 30, 2020, the available borrowing capacity under the BellRing Revolving Credit Facility was $170.0 and there were no outstanding letters of credit. Borrowings under the BellRing Term B Facility bear interest, at the option of BellRing, at an annual rate equal to either (a) the Eurodollar rate or (b) the base rate determined by reference to the greatest of (i) the prime rate, (ii) the federal funds effective rate plus 0.50% per annum and (iii) the one-month Eurodollar rate plus 1.00% per annum, in each case plus an applicable margin of 5.00% for Eurodollar rate-based loans and 4.00% for base rate-based loans. The BellRing Term B Facility requires quarterly scheduled amortization payments of $8.75, which began on March 31, 2020, with the balance to be paid at maturity on October 21, 2024. Interest was paid on each Interest Payment Date (as defined in the BellRing Credit Agreement) during the year ended September 30, 2020. The BellRing Term B Facility contains customary mandatory prepayment provisions, including provisions for mandatory prepayment (a) from the net cash proceeds of certain asset sales and (b) beginning with the fiscal year ending September 30, 2020, of 75% of consolidated excess cash flow (as defined in the BellRing Credit Agreement) (which percentage will be reduced to 50% if the secured net leverage ratio (as defined in the BellRing Credit Agreement) is less than or equal to 3.35:1.00 as of a fiscal year end). The Company classified $28.8 related to this mandatory prepayment of excess cash flow in “Current portion of long-term debt” on the Consolidated Balance Sheet at September 30, 2020. BellRing may prepay the BellRing Term B Facility at its option without penalty or premium. The interest rate on the BellRing Term B Facility was 6.00% at September 30, 2020. Borrowings under the BellRing Revolving Credit Facility bear interest, at the option of BellRing, at an annual rate equal to either the Eurodollar rate or the base rate (determined as described above) plus a margin, which initially were 4.25% for Eurodollar rate-based loans and 3.25% for base rate-based loans, and thereafter, will be determined by reference to the secured net leverage ratio, with the applicable margin for Eurodollar rate-based loans and base rate-based loans being (i) 4.25% and 3.25%, respectively, if the secured net leverage ratio is greater than or equal to 3.50:1.00, (ii) 4.00% and 3.00%, respectively, if the secured net leverage ratio is less than 3.50:1.00 and greater than or equal to 2.50:1.00 or (iii) 3.75% and 2.75%, respectively, if the secured net leverage ratio is less than 2.50:1.00. Facility fees on the daily unused amount of commitments under the BellRing Revolving Credit Facility initially accrued at the rate of 0.50% per annum and thereafter, depending on BellRing’s secured net leverage ratio, will accrue at rates ranging from 0.25% to 0.50% per annum. The interest rate on the drawn portion of the BellRing Revolving Credit Facility was 5.25% at September 30, 2020. The BellRing Credit Agreement provides for incremental revolving and term facilities, and also permits other secured or unsecured debt, if, among other conditions, certain financial ratios are met, as defined and specified in the BellRing Credit Agreement. The BellRing Credit Agreement provides for customary events of default, including material breach of representations and warranties, failure to make required payments, failure to comply with certain agreements or covenants, failure to pay or default under certain other material indebtedness, certain events of bankruptcy and insolvency, inability to pay debts, the occurrence of one or more unstayed or undischarged judgments in excess of $65.0, certain events under ERISA, the invalidity of any loan document, a change in control and the failure of the collateral documents to create a valid and perfected first priority lien. Upon the occurrence and during the continuance of an event of default, the maturity of the loans under the BellRing Credit Agreement may accelerate and the agent and lenders under the BellRing Credit Agreement may exercise other rights and remedies available at law or under the loan documents, including with respect to the collateral and guarantees of BellRing’s obligations under the BellRing Credit Agreement. Obligations under the BellRing Credit Agreement are guaranteed by the existing and subsequently acquired or organized domestic subsidiaries of BellRing (other than immaterial subsidiaries, certain excluded subsidiaries and subsidiaries of BellRing it designates as unrestricted subsidiaries) and are secured by security interests in substantially all of the assets of BellRing and the assets of its subsidiary guarantors (other than real estate), subject to limited exceptions. The Company and its subsidiaries (other than BellRing and certain of its subsidiaries) are not obligors or guarantors under the BellRing debt facilities. Repayments of Long-Term Debt The following table shows the Company’s repayments of long-term debt and associated gain or loss included in “Loss on extinguishment of debt, net” in the Consolidated Statements of Operations. Repayments of Long-Term Debt Loss on Extinguishment of Debt, net Year Ended Issuance Principal Amount Repaid Debt Repurchased at a Discount Premium and Debt Extinguishment Costs Paid Write-off of Debt Issuance Costs Write-off of Unamortized Premium Term Loan $ 1,309.5 $ — $ — $ 9.1 $ — 2020 Bridge Loan 1,225.0 — — 3.8 — 5.50% Senior Notes maturing in March 2025 1,000.0 — 41.3 8.7 — Revolving Credit Facility 500.0 — — — — BellRing Revolving Credit Facility 165.0 — — — — 8.00% Senior Notes 122.2 — 8.5 0.7 — BellRing Term B Facility 26.3 — — — — Municipal bond 1.1 — — — — Second AR Credit Agreement — — — 0.8 — 2020 Total $ 4,349.1 $ — $ 49.8 $ 23.1 $ — Term Loan $ 863.0 $ — $ — $ 7.6 $ — 5.75% Senior Notes 27.0 (1.5) — 0.3 (0.7) 5.625% Senior Notes 20.0 (1.3) — 0.2 — 5.00% Senior Notes 13.0 (1.2) — 0.1 — Capital lease 0.1 — — — — 2018 Bridge Loan (a) — — — 2.6 — 2019 Total $ 923.1 $ (4.0) $ — $ 10.8 $ (0.7) 6.00% Senior Notes $ 630.0 $ — $ 30.8 $ 6.5 $ — 5.625% Senior Notes 39.1 (2.1) — 0.4 — 5.75% Senior Notes 173.7 (3.1) — 1.9 (4.6) 5.00% Senior Notes 39.7 (2.5) — 0.4 — 8.00% Senior Notes 15.3 — 2.0 0.1 — Term Loan (b) 22.0 — 0.9 0.4 — 2018 Total $ 919.8 $ (7.7) $ 33.7 $ 9.7 $ (4.6) (a) In connection with the assumption of the 2018 Bridge Loan by 8th Avenue discussed above, the Company recorded a write-off of debt issuance costs during the year ended September 30, 2019 for costs that were not refunded upon the closing of the 8th Avenue Transactions. (b) In connection with the Second Amendment entered into on March 8, 2018, the Company paid debt extinguishment costs and recorded a write-off of debt issuance costs. Debt Covenants Second AR Credit Agreement Under the terms of the Second AR Credit Agreement, the Company is required to comply with a financial covenant consisting of a secured net leverage ratio (as defined in the Second AR Credit Agreement) not to exceed 4.25 to 1.00, measured as of the last day of any fiscal quarter, if, as of the last day of such fiscal quarter, the aggregate outstanding amount of all revolving credit loans, swing line loans and letter of credit obligations (subject to certain exceptions specified in the Second AR Credit Agreement) exceeds 30% of the Company’s revolving credit commitments. As of September 30, 2020, the Company was not required to comply with such financial covenant as the aggregate amount of the aforementioned obligations did not exceed 30% of the Company’s revolving credit commitments. The Second AR Credit Agreement provides for incremental revolving and term loan facilities, and also permits other secured or unsecured debt, if, among other conditions, certain financial ratios are met, as defined and specified in the Second AR Credit Agreement. BellRing Credit Agreement Under the terms of the BellRing Credit Agreement, BellRing is required to comply with a financial covenant requiring BellRing to maintain a total net leverage ratio (as defined in the BellRing Credit Agreement) not to exceed 6.00 to 1.00, measured as of the last day of each fiscal quarter. The total net leverage ratio of BellRing did not exceed this threshold as of September 30, 2020. The BellRing Credit Agreement provides for incremental revolving and term facilities, and also permits other secured or unsecured debt, if, among other conditions, certain financial ratios are met, as defined and specified in the BellRing Credit Agreement.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Legal Proceedings Antitrust Claims In late 2008 and early 2009, approximately 22 class action lawsuits were filed in various federal courts against Michael Foods, Inc. (“MFI”), a wholly-owned subsidiary of the Company, and approximately 20 other defendants (producers of shell eggs and egg products and egg industry organizations), alleging violations of federal and state antitrust laws in connection with the production and sale of shell eggs and egg products, and seeking unspecified damages. All cases were transferred to the Eastern District of Pennsylvania for coordinated and/or consolidated pretrial proceedings. The cases involved three plaintiff groups: (i) a nationwide class of direct purchasers of shell eggs (the “direct purchaser class”); (ii) individual companies (primarily large grocery chains and food companies that purchase considerable quantities of eggs) that opted out of various settlements and filed their own complaints related to their purchases of shell eggs and egg products (“opt-out plaintiffs”); and (iii) indirect purchasers of shell eggs (“indirect purchaser plaintiffs”). Resolution of claims: To date, MFI has resolved the following claims, including all class claims: (i) in December 2016, MFI settled all claims asserted against it by the direct purchaser class for a payment of $75.0, which was approved by the district court in December 2017; (ii) in January 2017, MFI settled all claims asserted against it by opt-out plaintiffs related to shell egg purchases on confidential terms; (iii) in June 2018, MFI settled all claims asserted against it by indirect purchaser plaintiffs on confidential terms; and (iv) between June 2019 and September 2019, MFI individually settled on confidential terms egg product opt-out claims asserted against it by four separate opt-out plaintiffs. MFI has at all times denied liability in this matter, and no settlement contains any admission of liability by MFI. Remaining portion of the cases: MFI remains a defendant only with respect to claims that seek damages based on purchases of egg products by three opt-out plaintiffs. The district court had granted summary judgment precluding any claims for egg products purchases by such opt-out plaintiffs, but the Third Circuit Court of Appeals reversed and remanded these claims for further pre-trial proceedings. Defendants filed a second motion for summary judgment seeking dismissal of the claims, which was denied in June 2019. The remaining opt-out plaintiffs have not yet been assigned trial dates. Although the likelihood of a material adverse outcome in the egg antitrust litigation has been significantly reduced as a result of the MFI settlements described above, the remaining portion of the cases could still result in a material adverse outcome. At September 30, 2020 and 2019, the Company had accrued $3.5 and $6.2, respectively, for this matter that was included in “Other current liabilities” on the Consolidated Balance Sheets. The Company records reserves for litigation losses in accordance with ASC Topic 450, “Contingencies.” Under ASC Topic 450, a loss contingency is recorded if a loss is probable and can be reasonably estimated. The Company records probable loss contingencies based on the best estimate of the loss. If a range of loss can be reasonably estimated, but no single amount within the range appears to be a better estimate than any other amount within the range, the minimum amount in the range is accrued. These estimates are often initially developed earlier than when the ultimate loss is known, and the estimates are adjusted if additional information becomes known. Although the Company believes its accruals for this matter are appropriate, the final amounts required to resolve such matter could differ materially from recorded estimates and the Company’s consolidated financial condition, results of operations and cash flows could be materially affected. During the years ended September 30, 2019 and 2018, the Company expensed $5.0 and $8.3 related to these settlements, respectively, which was included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. No expense was recorded in the year ended September 30, 2020 related to these matters. Under current law, any settlement paid, including the settlements with the direct purchaser plaintiffs, the opt-out plaintiffs and the indirect purchaser plaintiffs, is deductible for federal income tax purposes. Bob Evans Appraisal Proceedings Prior to completion of the Company’s acquisition of Bob Evans on January 12, 2018, Bob Evans received demands from certain stockholders demanding appraisal of their shares of Bob Evans common stock. After the completion of the acquisition, several such former stockholders filed petitions in the Delaware Court of Chancery ( Arbitrage Fund v. Bob Evans Farms, Inc. filed on January 23, 2018; Blue Mountain Credit Alternatives Master Fund L.P., et al. v. Bob Evans Farms, Inc. filed on April 30, 2018; and 2017 Clarendon LLC, et al. v. Bob Evans Farms, Inc. filed on April 30, 2018) seeking appraisal of their shares of Bob Evans common stock pursuant to Section 262 of the Delaware General Corporation Law (“Section 262”). The lawsuits sought appraisal for such shares, plus statutory interest, as well as the costs of the proceedings and such other relief as appropriate. Under Section 262, persons who were stockholders at the time of the closing were entitled to have their shares appraised by the Delaware Court of Chancery and receive payment of the “fair value” of such shares (plus statutory interest) as determined by the Delaware Court of Chancery. In May 2018, the court consolidated the lawsuits into one action. In December 2018, the Company settled with one petitioner, Arbitrage Fund, and Arbitrage Fund was dismissed with prejudice from the consolidated action. In addition, in December 2018, the Company pre-paid the $77.00 per share merger consideration to the Blue Mountain and 2017 Clarendon petitioners, effectively stopping the continued accrual of statutory interest on that amount. The Company made total payments of $257.6 , inclusive of the aforementioned prepayment of $77.00 per share merger consideration, related to these matters in fiscal 2019. In September 2019, the Company reached settlement terms on a confidential basis with the remaining petitioners regarding their outstanding appraisal claims. The settlement was finalized and the remaining portion of the case was dismissed in October 2019. All former Bob Evans stockholders who demanded appraisal of their shares were paid for their shares of Bob Evans common stock. At September 30, 2019, the Company had an accrual of $19.1, which was reported in “Other current liabilities” on the Consolidated Balance Sheet. All remaining cash payments related to these matters were made in October 2019 and there was no accrual reported on the Consolidated Balance Sheet at September 30, 2020. During the years ended September 30, 2019 and 2018, the Company expensed $9.7 and $13.4, respectively, related to these matters. The expense was included in “Selling, general and administrative expenses” and “Interest expense, net” in the Consolidated Statement of Operations for the year ended September 30, 2019 and in “Interest expense, net” in the Consolidated Statement of Operations for the year ended September 30, 2018. No expense was recorded in the year ended September 30, 2020 related to these matters. Other The Company is subject to various other legal proceedings and actions arising in the normal course of business. In the opinion of management, based upon the information presently known, the ultimate liability, if any, arising from such pending legal proceedings, as well as from asserted legal claims and known potential legal claims which are likely to be asserted, taking into account established accruals for estimated liabilities (if any), are not expected to be material individually or in the aggregate to the consolidated financial condition, results of operations or cash flows of the Company. In addition, although it is difficult to estimate the potential financial impact of actions regarding expenditures for compliance with regulatory matters, in the opinion of management, based upon the information currently available, the ultimate liability arising from such compliance matters is not expected to be material to the consolidated financial condition, results of operations or cash flows of the Company. Bob Evans Lease Guarantees Historically, Bob Evans guaranteed certain payment and performance obligations associated with the leases for 143 properties (the “Guarantees”) leased by the restaurant business formerly owned by Bob Evans (the “Bob Evans Restaurant Business”). The Guarantees remained in effect following the Company’s acquisition of Bob Evans. In the event the Bob Evans Restaurant Business fails to meet its payment and performance obligations under these leases, subject in certain cases to certain early termination allowances, the Company may be required to make rent and other payments to the landlord under the requirements of the Guarantees. Should the Company, as guarantor of the lease obligations, be required to make all lease payments due for the remaining term of the leases subsequent to September 30, 2020, the maximum amount the Company may be required to pay is equal to the annual rent amount for the remainder of the lease terms. The current annual rent on these leases is $13.9 and will increase up to 1.5% annually based on indexed inflation. The lease terms for the majority of the leases extend for approximately 17 years from September 30, 2020, and the Guarantees would remain in effect in the event the leases are extended for a renewal period. In the event the Company is obligated to make payments under any of the Guarantees, the Company believes its exposure is limited due to protections and recourse available in the leases associated with the leased properties, including a requirement of the landlord to mitigate damages by re-letting the properties in default. While the COVID-19 pandemic has impacted the restaurants industry generally, including the Bob Evans Restaurant Business, the Bob Evans Restaurant Business was able to amend certain of its leases during fiscal 2020 in order to ensure that it continues to meet

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	12 Months Ended
	Sep. 30, 2020
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension and Other Postretirement Benefits	PENSION AND OTHER POSTRETIREMENT BENEFITSThe Company maintains qualified defined benefit plans in the U.S., the U.K. and Canada for certain employees primarily within its Post Consumer Brands and Weetabix segments. Certain of the Company’s employees are eligible to participate in the Company’s postretirement benefit plans (partially subsidized retiree health and life insurance). The following disclosures reflect amounts related to the Company’s employees based on separate actuarial valuations, projections and certain allocations. Amounts for the Canadian plans are included in the North America disclosures and are not disclosed separately because they do not constitute a significant portion of the combined amounts. With respect to defined benefits for Canadian Post Consumer Brands employees, eligibility is frozen to new entrants and benefit accrual is frozen for salaried employees. With respect to defined benefits for U.S. Post Consumer Brands employees, eligibility is frozen to new employees and the benefit accruals are frozen for all administrative employees and certain production employees. The benefit accrual is frozen for salaried Weetabix North America employees in the U.S. With respect to Weetabix employees in the U.K participating in the executive and group schemes of the defined benefit pension plans, eligibility is frozen to new entrants and the benefit accrual is frozen with respect to participants. Defined Benefit Pension Plans The following table provides a reconciliation of the changes in the pension plans’ benefit obligations and fair value of assets over the two year period ended September 30, 2020 and a statement of the funded status and amounts recognized on the Consolidated Balance Sheets as of September 30, 2020 and 2019. North America Other International Year Ended Year Ended 2020 2019 2020 2019 Change in benefit obligation Benefit obligation at beginning of period $ 121.5 $ 100.9 $ 780.5 $ 691.2 Service cost 4.3 3.7 — 5.6 Interest cost 3.7 4.1 14.7 18.9 Plan participants’ contributions 0.5 0.5 — 2.2 Prior service cost (a) — — 11.4 1.5 Actuarial loss 6.6 17.3 17.6 126.6 Benefits paid (5.4) (4.6) (25.9) (26.2) Currency translation (0.1) (0.4) 36.1 (39.3) Benefit obligation at end of period $ 131.1 $ 121.5 $ 834.4 $ 780.5 Change in fair value of plan assets Fair value of plan assets at beginning of period $ 119.7 $ 114.1 $ 946.9 $ 844.5 Actual return on plan assets 6.4 9.8 28.1 169.9 Employer contributions 0.4 0.3 — 4.8 Plan participants’ contributions 0.5 0.5 — 2.2 Benefits paid (5.4) (4.6) (25.9) (26.2) Currency translation (0.1) (0.4) 44.1 (48.3) Fair value of plan assets at end of period 121.5 119.7 993.2 946.9 Funded status $ (9.6) $ (1.8) $ 158.8 $ 166.4 Amounts recognized in assets or liabilities Other assets $ 0.2 $ 0.3 $ 158.8 $ 166.4 Other liabilities (9.8) (2.1) — — Net amount recognized $ (9.6) $ (1.8) $ 158.8 $ 166.4 Amounts recognized in accumulated other comprehensive loss Net actuarial loss (gain) $ 28.2 $ 23.4 $ (32.3) $ (46.5) Prior service cost 0.3 0.4 11.5 0.1 Total $ 28.5 $ 23.8 $ (20.8) $ (46.4) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 3.01 % 3.32 % n/a n/a Discount rate — Canadian plans 2.71 % 2.84 % n/a n/a Discount rate — Other international plans n/a n/a 1.73 % 1.84 % Rate of compensation increase — U.S. plans 3.00 % 3.00 % n/a n/a Rate of compensation increase — Canadian plans 2.75 % 2.75 % n/a n/a Rate of compensation increase — Other international plans n/a n/a 2.65 % 2.55 % (a) During the year ended September 30, 2020, the Company recognized prior service cost as a result of an amendment to the benefit plan for Weetabix employees in the U.K. participating in the group scheme. During the year ended September 30, 2019, the Company recognized prior service cost as a result of U.K. high court rulings made in connection with the Guaranteed Minimum Pension (the “GMP”). The accumulated benefit obligation exceeded the fair value of plan assets for the North American pension plans at September 30, 2020, whereas the fair value of plan assets for the North American pension plans equaled the accumulated benefit obligation at September 30, 2019. The fair value of plan assets for the other international pension plans exceeded the accumulated benefit obligation at September 30, 2020 and 2019. The aggregate accumulated benefit obligation for the North American pension plans was $129.3 and $119.7 at September 30, 2020 and 2019, respectively. The aggregate accumulated benefit obligation for the other international pension plans was $831.1 and $776.4 at September 30, 2020 and 2019, respectively. The following tables provide the components of net periodic benefit cost for the pension plans including amounts recognized in OCI. For the years ended September 30, 2020, 2019 and 2018, service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit cost were reported in “Other income, net” in the Consolidated Statements of Operations. North America Year Ended September 30, 2020 2019 2018 Components of net periodic benefit cost Service cost $ 4.3 $ 3.7 $ 4.2 Interest cost 3.7 4.1 3.6 Expected return on plan assets (6.4) (6.4) (4.4) Recognized net actuarial loss 1.8 — 1.1 Recognized prior service cost 0.1 0.1 0.1 Net periodic benefit cost $ 3.5 $ 1.5 $ 4.6 Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans 3.32 % 4.30 % 3.86 % Discount rate — Canadian plans 2.84 % 3.53 % 3.63 % Rate of compensation increase — U.S. plans 3.00 % 3.00 % 3.00 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.69 % Expected return on plan assets — U.S. plans 5.53 % 5.74 % 5.46 % Expected return on plan assets — Canadian plans 5.75 % 5.75 % 6.00 % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income Net loss (gain) $ 6.6 $ 13.9 $ (3.7) Recognized loss (1.8) — (1.1) Recognized prior service cost (0.1) (0.1) (0.1) Total recognized in other comprehensive income (before tax effects) $ 4.7 $ 13.8 $ (4.9) Other International Year Ended September 30, 2020 2019 2018 Components of net periodic benefit cost Service cost $ — $ 5.6 $ 6.7 Interest cost 14.7 18.9 19.6 Expected return on plan assets (24.6) (28.8) (31.7) Recognized curtailment (a) — 1.5 — Net periodic benefit income $ (9.9) $ (2.8) $ (5.4) Weighted-average assumptions used to determine net benefit cost Discount rate 1.84 % 2.81 % 2.72 % Rate of compensation increase 2.55 % 2.75 % 2.70 % Expected return on plan assets 2.53 % 3.51 % 3.56 % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income Net loss (gain) $ 14.2 $ (14.4) $ 8.2 Prior service cost (b) 11.4 1.5 — Recognized curtailment (a) — (1.5) — Total recognized in other comprehensive income (before tax effects) $ 25.6 $ (14.4) $ 8.2 (a) In September 2019, the Company signed an amendment to the pension deed to close the defined benefit plan for Weetabix employees in the U.K. participating in the group scheme. Eligibility is frozen to new entrants, and the benefit accrual is frozen with respect to current participants. Due to the closure of the group scheme plan, the prior service cost recognized in accumulated OCI in connection with the GMP high court rulings was reclassified to earnings during the year ended September 30, 2019. (b) During the year ended September 30, 2020, the Company recognized prior service cost as a result of an amendment to the benefit plan for Weetabix employees in the U.K. participating in the group scheme. During the year ended September 30, 2019, the Company recognized prior service cost as a result of U.K. high court rulings made in connection with the GMP. The Company expects to make contributions of $0.2 and zero to its defined benefit North American and other international pension plans, respectively, during fiscal 2021. The expected return on North American pension plan assets was determined based on historical and expected future returns of the various asset classes, using the target allocation. The broad target allocations are 55.6% equity securities, 40.8% fixed income and bonds, 2.6% real assets and 1.0% cash and cash equivalents. At September 30, 2020, equity securities were 58.3%, fixed income and bonds were 40.6%, real assets were 0.1% and cash and cash equivalents were 1.0% of the fair value of total plan assets, 99.5% of which was invested in passive index funds. At September 30, 2019, equity securities were 46.4%, fixed income and bonds were 47.3%, real assets were 5.3% and cash and cash equivalents were 1.0% of the fair value of total plan assets, 99.6% of which was invested in passive index funds. The allocation guidelines were established based on management’s determination of the appropriate risk posture and long-term objectives. The expected return on other international pension plan assets was determined based on historical and expected future returns of the various asset classes, using the target allocation. The broad target allocations are 67.1% fixed income and bonds, 30.2% liability driven investments, 2.5% real assets and 0.2% cash and cash equivalents. At September 30, 2020, fixed income and bonds were 69.6%, liability driven investments were 27.2%, real assets were 1.3% and cash and cash equivalents were 1.9% of the fair value of total plan assets, 34.4% of which was invested in passive index funds. At September 30, 2019, fixed income and bonds were 62.5%, liability driven investments were 30.1%, real assets was 1.7% and cash and cash equivalents were 5.7% of the fair value of total plan assets, 33.7% of which was invested in passive index funds. The allocation guidelines were established by the trustees of the plan based on their determination of the appropriate risk posture and long-term objectives after consulting with management. The following tables present the North American and other international pension plans’ assets measured at fair value on a recurring basis and the basis for that measurement. The fair value of funds is based on quoted net asset values of the shares held by the plans at year end. Certain prior year amounts have been reclassified to conform with fiscal 2020 presentation. North America September 30, 2020 September 30, 2019 Total Level 1 Level 2 Total Level 1 Level 2 Equities $ 10.5 $ — $ 10.5 $ 9.9 $ — $ 9.9 Fixed income and bonds 5.5 — 5.5 5.3 — 5.3 Cash and cash equivalents 1.3 1.3 — 1.2 1.2 — Fair value of plan assets in the fair value hierarchy 17.3 1.3 16.0 16.4 1.2 15.2 Equities 60.3 — — 45.6 — — Fixed income and bonds 43.8 — — 51.3 — — Real assets 0.1 — — 6.4 — — Investments measured at net asset value (a) 104.2 — — 103.3 — — Total plan assets $ 121.5 $ 1.3 $ 16.0 $ 119.7 $ 1.2 $ 15.2 Other International September 30, 2020 September 30, 2019 Total Level 1 Level 2 Total Level 1 Level 2 Fixed income and bonds $ 642.1 $ 642.1 $ — $ 554.8 $ 554.8 $ — Liability driven instruments 241.6 241.6 — 258.6 258.6 — Cash and cash equivalents 16.1 16.1 — 51.3 51.3 — Fair value of plan assets in the fair value hierarchy 899.8 899.8 — 864.7 864.7 — Fixed income and bonds 49.2 — — 37.0 — — Liability driven instruments 28.6 — — 26.0 — — Real assets 12.8 — — 16.5 — — Cash and cash equivalents 2.8 — — 2.7 — — Investments measured at net asset value (a) 93.4 — — 82.2 — — Total plan assets $ 993.2 $ 899.8 $ — $ 946.9 $ 864.7 $ — (a) In accordance with ASC Topic 820-10, certain investments were measured at net asset value per share (“NAV”). In cases where the fair value was measured at NAV using the practical expedient provided for in ASC Topic 820-10, the investments have not been classified in the fair value hierarchy. The fair value amounts presented in these tables are intended to permit reconciliation of the fair value hierarchy to the tables above. Other Postretirement Benefits The following table provides a reconciliation of the changes in the North American other postretirement benefit obligations over the two year period ended September 30, 2020. Besides the North American plans, the Company does not maintain any other postretirement benefit plans. Year Ended 2020 2019 Change in benefit obligation Benefit obligation at beginning of period $ 66.4 $ 55.2 Service cost 0.6 0.4 Interest cost 1.9 2.1 Actuarial loss 4.6 11.5 Benefits paid (2.7) (2.6) Currency translation (0.1) (0.2) Benefit obligation at end of period $ 70.7 $ 66.4 Change in fair value of plan assets Employer contributions 2.7 2.6 Benefits paid (2.7) (2.6) Fair value of plan assets at end of period — — Funded status $ (70.7) $ (66.4) Amounts recognized in assets or liabilities Other current liabilities (2.8) (2.5) Other liabilities (67.9) (63.9) Net amount recognized $ (70.7) $ (66.4) Amounts recognized in accumulated other comprehensive loss Net actuarial loss $ 14.3 $ 10.3 Prior service credit (14.7) (19.4) Total $ (0.4) $ (9.1) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 2.79 % 3.20 % Discount rate — Canadian plans 2.78 % 2.86 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % The following table provides the components of net periodic benefit cost for the other postretirement benefit plans including amounts recognized in OCI. For the years ended September 30, 2020, 2019 and 2018, service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit cost were reported in “Other income, net” in the Consolidated Statements of Operations. Year Ended September 30, 2020 2019 2018 Components of net periodic benefit cost Service cost $ 0.6 $ 0.4 $ 0.5 Interest cost 1.9 2.1 2.1 Recognized net actuarial loss 0.6 — 0.3 Recognized prior service credit (4.7) (4.7) (4.7) Net periodic benefit cost $ (1.6) $ (2.2) $ (1.8) Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans 3.20 % 4.27 % 3.77 % Discount rate — Canadian plans 2.86 % 3.54 % 3.69 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Changes in benefit obligation recognized in Total Comprehensive Income Net loss (gain) $ 4.6 $ 11.5 $ (9.9) Recognized net actuarial loss (0.6) — (0.3) Recognized prior service credit 4.7 4.7 4.7 Currency translation — — 0.4 Total recognized in other comprehensive income (before tax effects) $ 8.7 $ 16.2 $ (5.1) For September 30, 2020 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to domestic plans for 2021 was 6.1% for participants both under the age of 65 and over the age of 65, declining gradually to an ultimate rate of 5.0% for 2025 and beyond. For September 30, 2019 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to domestic plans for 2020 was 6.3% for participants both under the age of 65 and over the age of 65, declining gradually to an ultimate rate of 5.0% for 2025 and beyond. For September 30, 2020 and 2019 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to Canadian plans for the following fiscal year was 5.0% and 5.5%, respectively, declining gradually to an ultimate rate of 4.5% for 2021 and beyond for the years ended September 30, 2020 and 2019. Additional Information As of September 30, 2020, expected future benefit payments and related federal subsidy receipts (Medicare Part D) in the next ten fiscal years were as follows: 2021 2022 2023 2024 2025 2025- 2029 Pension benefits $ 25.2 $ 26.3 $ 27.3 $ 28.5 $ 29.8 $ 168.9 Other benefits 2.9 3.2 3.5 3.6 3.6 18.3 Subsidy receipts 0.1 0.1 0.1 0.2 0.2 1.0

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATIONThe Company’s employees, including BellRing employees, participate in Post’s 2012 Long-Term Incentive Plan (the “Post 2012 Plan”), Post’s 2016 Long-Term Incentive Plan (the “Post 2016 Plan”) and Post’s 2019 Long-Term Incentive Plan (the “Post 2019 Plan”) (collectively, the “Post Long-Term Incentive Plans”). Subsequent to the IPO, BellRing’s employees also began participating in Belling’s 2019 Long-Term Incentive Plan (the “BellRing 2019 Plan”). Post Long-Term Incentive Plans On February 3, 2012, the Company established the Post 2012 Plan, which permitted the issuance of various stock-based compensation awards of up to 6.5 shares. On January 28, 2016, the Company’s shareholders approved the Post 2016 Plan, which permitted the issuance of stock-based compensation awards of up to 2.4 shares. Upon the effectiveness of the Post 2016 Plan, all remaining shares available to be issued under the Post 2012 Plan were transferred to the Post 2016 Plan. On January 24, 2019, the Company’s shareholders approved the Post 2019 Plan, which permits the issuance of stock-based compensation awards of up to 1.2 shares, plus shares remaining to be issued under the Post 2016 Plan (including any shares assumed thereunder from the Post 2012 Plan) which were transferred to the Post 2019 Plan upon its effectiveness. Awards issued under the Post Long-Term Incentive Plans have a maximum term of 10 years, provided, however, that the Corporate Governance and Compensation Committee of the Company’s Board of Directors may, in its discretion, grant awards with a longer term to participants who are located outside of the U.S. The following disclosures reflect the details of Post’s Long-Term Incentive Plans, which includes BellRing employees who participate in such plans. Total compensation cost for Post’s cash and non-cash stock-based compensation awards recognized in the years ended September 30, 2020, 2019 and 2018 was $47.1, $39.7 and $33.8, respectively, and the related recognized deferred tax benefit for each of those periods was approximately $7.0, $6.6 and $7.8, respectively. As of September 30, 2020, the total compensation cost related to Post’s non-vested awards not yet recognized was $59.7, which is expected to be recognized over a weighted-average period of 1.7 years. Post Stock Appreciation Rights (“Post SSARs”) Information about Post SSARs is summarized in the following table. Upon exercise of each Post SSAR, the holder will receive the number of shares of Post common stock equal in value to the difference between the exercise price and the fair market value at the date of exercise, less all applicable taxes. The total intrinsic value of Post SSARs exercised was $0.1 and $0.1 during the years ended September 30, 2020 and 2018, respectively. There were no Post SSARs exercised during the year ended September 30, 2019.There were no Post SSARs granted during the years ended September 30, 2020, 2019 or 2018. in millions, except Post SSARs or where otherwise indicated Post SSARs Weighted- Weighted- Aggregate Outstanding at September 30, 2019 136,031 $ 41.94 Granted — — Exercised (1,031) 18.10 Forfeited — — Expired — — Outstanding at September 30, 2020 135,000 42.12 2.75 $ 5.9 Vested and expected to vest as of September 30, 2020 135,000 42.12 2.75 5.9 Exercisable at September 30, 2020 135,000 42.12 2.75 5.9 Post Cash Settled Stock Appreciation Rights (“Post SARs”) Information about Post SARs is summarized in the following table. There were no Post SARs granted during the years ended September 30, 2020, 2019 or 2018. Cash used by the Company to settle Post SARs was $0.2 and $5.0 during the years ended September 30, 2020 and 2018, respectively. There were no cash settlements of Post SARs during the year ended September 30, 2019. in millions, except Post SARs or where otherwise indicated Post SARs Weighted- Weighted- Aggregate Outstanding at September 30, 2019 2,500 $ 18.10 Granted — — Exercised (2,500) 18.10 Forfeited — — Expired — — Outstanding at September 30, 2020 — n/a n/a n/a Vested and expected to vest as of September 30, 2020 — n/a n/a n/a Exercisable at September 30, 2020 — n/a n/a n/a The fair value of each Post SAR was estimated for each reporting period using the Black-Scholes Model. The expected term is estimated based on the award’s vesting period and contractual term, along with historical exercise behavior on similar awards. Expected volatilities are based on historical volatility trends and other factors. The risk-free rate is the interpolated U.S. Treasury rate for a term equal to the expected term. The following table presents the assumptions used to remeasure the fair value of outstanding Post SARs. 2019 2018 Expected term (in years) 0 0.0 Expected stock price volatility 24.8% 21.5% Risk-free interest rate 1.8% 2.6% Expected dividends 0% 0% Fair value (per Post SAR) $87.84 $79.94 Post Stock Options in millions, except Post stock options or where otherwise indicated Post Stock Options Weighted- Weighted- Aggregate Outstanding at September 30, 2019 1,758,026 $ 58.03 Granted 30,504 106.51 Exercised (89,250) 44.11 Forfeited — — Expired — — Outstanding at September 30, 2020 1,699,280 59.63 5.21 $ 46.1 Vested and expected to vest as of September 30, 2020 1,699,280 59.63 5.21 46.1 Exercisable at September 30, 2020 1,509,246 55.91 4.88 45.6 The fair value of each Post stock option was estimated on the date of grant using the Black-Scholes Model. The Company uses the simplified method for estimating a Post stock option term as it does not have sufficient historical stock options exercise experience upon which to estimate an expected term. The expected term is estimated based on the award’s vesting period and contractual term. Expected volatilities are based on historical volatility trends and other factors. The risk-free rate is the interpolated U.S. Treasury rate for a term equal to the expected term. The weighted-average assumptions and fair values for Post stock options granted are summarized in the table below. 2020 2019 2018 Expected term (in years) 6.5 6.5 6.5 Expected stock price volatility 29.2% 29.7% 30.7% Risk-free interest rate 1.8% 3.1% 2.2% Expected dividends 0% 0% 0% Fair value (per Post stock option) $35.32 $33.82 $28.52 The total intrinsic value of Post stock options exercised was $5.5, $148.2 and $4.7 in the years ended September 30, 2020, 2019 and 2018, respectively. The Company received proceeds from the exercise of Post stock options of $3.9, $112.6 and $5.7 during the years ended September 30, 2020, 2019 and 2018, respectively. Post Restricted Stock Units (“Post RSUs”) in millions, except Post RSUs or where otherwise indicated Post RSUs Weighted- Nonvested at September 30, 2019 1,013,939 $ 81.27 Granted 351,786 103.97 Vested (413,820) 82.16 Forfeited (21,972) 95.08 Nonvested at September 30, 2020 929,933 89.14 The grant date fair value of each Post RSU award was determined based upon the closing price of the Company’s common stock on the date of grant. The weighted-average grant date fair value of nonvested Post RSUs was $89.14, $81.27 and $71.94 at September 30, 2020, 2019 and 2018, respectively. The total vest date fair value of Post RSUs that vested during fiscal 2020, 2019 and 2018 was $42.1, $24.9 and $17.4, respectively. In fiscal 2018, 11,400 of the 13,300 Post RSUs granted by the Company to its non-management members of the Board of Directors had subjective acceleration rights such that the Company expensed the grant date fair value upon issuance and recognized related expense of $0.9 in the year ended September 30, 2018. None of the Post RSUs granted in fiscal 2020 and 2019 to non-management members of the Board of Directors had subjective acceleration rights and those awards are being amortized over the terms of the awards. Post Cash Settled Restricted Stock Units (“Post Cash RSUs”) in millions, except Post Cash RSUs or where otherwise indicated Post Cash RSUs Weighted- Nonvested at September 30, 2019 49,000 $ 51.43 Granted — — Vested (9,800) 51.43 Forfeited — — Nonvested at September 30, 2020 39,200 51.43 At September 30, 2020, the 39,200 nonvested Post Cash RSUs were valued at the greater of the closing stock price or the grant price of $51.43 . Cash used by the Company to settle Post Cash RSUs was $0.9, $1.1 and $3.2 for the years ended September 30, 2020, 2019 and 2018, respectively. Post Performance-Based Restricted Stock Units (“Post PRSUs”) in millions, except Post PRSUs or where otherwise indicated Post PRSUs Weighted- Nonvested at September 30, 2019 82,871 $ 112.75 Granted 90,836 138.10 Vested — — Forfeited — — Nonvested at September 30, 2020 173,707 126.00 During the years ended September 30, 2020, 2019 and 2018, the Company granted Post PRSUs to certain employees. These awards will be earned by comparing Post’s total shareholder return (“TSR”) during a three year period to the respective TSRs of companies in a performance peer group. Based upon Post’s ranking in its performance peer group when comparing TSRs, a recipient of the Post PRSU grant may earn a total award ranging from 0% to 200% of the target award. The fair value of each Post PRSU was estimated on the grant date using a Monte Carlo simulation. The assumptions for Post PRSUs granted during the years ended September 30, 2020, 2019 and 2018 are summarized in the table below. 2020 2019 2018 Expected term (in years) 3.0 3.0 3.0 Expected stock price volatility 22.2% 24.2% 31.8% Risk-free interest rate 1.6% 2.9% 1.8% Fair value (per Post PRSU) $138.10 $122.34 $97.74 BellRing Long-Term Incentive Plan On October 22, 2019, BellRing registered shares of its Class A Common Stock on a Form S-8 filed with the SEC, for issuance under the BellRing 2019 Plan, which permits the issuance of various stock-based compensation awards of up to 2.0 shares of BellRing’s Class A Common Stock. Awards issued under the BellRing 2019 Plan have a maximum term of 10 years, provided, however, that the corporate governance and compensation committee of BellRing’s board of directors may, in its discretion, grant awards with a longer term to participants who are located outside of the U.S. Total compensation cost for BellRing’s non-cash stock-based compensation awards recognized in the year ended September 30, 2020 was $2.5, and the related recognized deferred tax benefit was $0.6. As of September 30, 2020, the total compensation cost related to BellRing’s non-vested awards not yet recognized was $5.7, which is expected to be recognized over a weighted-average period of 2.7 years. BellRing Stock Options Information about BellRing’s stock options is summarized in the following table. in millions, except BellRing stock options or where otherwise indicated BellRing Stock Options Weighted- Weighted- Aggregate Outstanding at September 30, 2019 — $ — Granted 96,000 19.31 Exercised — — Forfeited — — Expired — — Outstanding at September 30, 2020 96,000 19.31 9.15 $ 0.1 Vested and expected to vest as of September 30, 2020 96,000 19.31 9.15 0.1 Exercisable at September 30, 2020 — n/a n/a n/a The fair value of each BellRing stock option was estimated on the date of grant using the Black-Scholes Model. BellRing uses the simplified method for estimating a BellRing stock option term as it does not have sufficient historical stock options exercise experience upon which to estimate an expected term. The expected term is estimated based on the award’s vesting period and contractual term. Expected volatilities are based on historical volatility trends and other factors. The risk-free rate is the interpolated U.S. Treasury rate for a term equal to the expected term. The weighted-average assumptions and fair values for BellRing stock options granted during the year ended September 30, 2020 are summarized in the table below. 2020 Expected term (in years) 6.5 Expected stock price volatility 38.5% Risk-free interest rate 1.6% Expected dividends 0% Fair value (per BellRing option) $7.92 BellRing Restricted Stock Units (“BellRing RSUs”) Information about BellRing’s RSUs is summarized in the following table. in millions, except BellRing RSUs or where otherwise indicated BellRing RSUs Weighted- Nonvested at September 30, 2019 — $ — Granted 395,232 19.39 Vested — — Forfeited (10,000) 19.31 Nonvested at September 30, 2020 385,232 19.39 The grant date fair value of each BellRing RSU was determined based upon the closing price of BellRing’s Class A Common Stock on the date of grant. Deferred Compensation Post provides deferred compensation plans for directors and key employees through which eligible participants may elect to defer payment of all or a portion of their compensation, or with respect to key employee participants, all or a portion of their eligible annual bonus, until a later date based on the participant’s elections. Participant deferrals for employee participants may be notionally invested in Post common stock equivalents (the “Equity Option”) or into a number of funds operated by The Vanguard Group Inc. with a variety of investment strategies and objectives (the “Vanguard Funds”). In order to receive a 33.3% matching contribution, deferrals for director participants must be made into Post common stock equivalents. Deferrals into the Equity Option are generally distributed in Post stock for employees and cash for directors, while deferrals into the Vanguard Funds are distributed in cash. There are no significant costs related to the administration of the deferred compensation plans. Post funds its deferred compensation liability (potential cash distributions) by investing in the Vanguard Funds in substantially the same amounts as selected by the participating employees. Both realized and unrealized gains and losses on these investments are included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations and offset the related change in the deferred compensation liability. For additional information, refer to Note 15.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Sep. 30, 2020
Stockholders' Equity Attributable to Parent [Abstract]
Shareholders' Equity	SHAREHOLDERS’ EQUITY The following table summarizes the Company’s repurchases of its common stock. September 30, 2020 2019 2018 Shares repurchased 6.1 3.3 2.8 Average share price $ 97.67 $ 98.78 $ 76.21 Total cost including broker’s commissions (a) $ 587.8 $ 330.8 $ 218.7 (a) Of the $587.8 total cost recorded during the year ended September 30, 2020, $7.4 was not settled until October 2020 and was included in “Other current liabilities” on the Consolidated Balance Sheet at September 30, 2020. Of the $330.8 total cost recorded during the year ended September 30, 2019, $8.7 was not settled until October 2019 and was included in “Other current liabilities” on the Consolidated Balance Sheet at September 30, 2019. The Company may, from time to time, enter into common stock structured repurchase arrangements with financial institutions using general corporate funds. Under such arrangements, the Company pays a fixed sum of cash upon execution of each agreement in exchange for the right to receive either a predetermined amount of cash or Post common stock. Upon expiration of each agreement, if the closing market price of Post’s common stock is above the predetermined price, the Company will have the initial investment returned with a premium in cash. If the closing market price of Post’s common stock is at or below the predetermined price, the Company will receive the number of shares specified in the agreement. During the year ended September 30, 2020, the Company entered into a structured share repurchase arrangement which required cash payments totaling $46.4, which were recorded as “Additional paid-in capital” on the Consolidated Balance Sheet at September 30, 2020 and as “Cash paid for stock repurchase contracts” in the Consolidated Statement of Cash Flows for year ended September 30, 2020. This arrangement will settle in November 2020 (subsequent to the end of the period) and will result in the receipt of either 0.6 shares of Post’s common stock or cash of $47.5.

Segments

Segments	12 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segments	SEGMENTS At September 30, 2020, the Company’s reportable segments were as follows: • Post Consumer Brands: North American RTE cereal; • Weetabix: primarily U.K. RTE cereal and muesli; • Foodservice: primarily egg and potato products; • Refrigerated Retail: primarily side dish, egg, cheese and sausage products; and • BellRing Brands: RTD protein shakes, other RTD beverages, powders and nutrition bars. Due to the level of integration between the Foodservice and Refrigerated Retail segments, it is impracticable to present additions to property and intangibles and total assets separately for each segment. An allocation has been made between the two segments for depreciation based on inventory costing. Management evaluates each segment’s performance based on its segment profit, which is its earnings before income taxes and equity method earnings/loss before impairment of property, goodwill and other intangible assets, facility closure related costs, restructuring expenses, gain/loss on assets and liabilities held for sale, gain/loss on sales of businesses and facilities, gain on bargain purchase, interest expense and other unallocated corporate income and expenses. In fiscal 2020, 2019 and 2018, Post’s external revenues were primarily generated by sales within the U.S.; foreign (primarily located in the U.K. and Canada) sales were 13.9%, 12.8% and 12.9% of total net sales, respectively. Sales are attributed to individual countries based on the address to which the product is shipped. As of September 30, 2020 and 2019, the majority of Post’s tangible long-lived assets were located in the U.S.; the remainder were located primarily in the U.K. and Canada which combined have a net carrying value of approximately $294.2 and $279.0, respectively. In the years ended September 30, 2020, 2019 and 2018, one customer, including its affiliates, accounted for 20.9%, 20.9% and 17.6%, respectively, of total net sales. All segments, except Foodservice, sold products to this major customer or its affiliates. The following tables present information about the Company’s reportable segments. In addition, the tables present net sales by product. The historical Private Brands segment manufactured and distributed private label peanut and other nut butters, dried fruit and nut products, granola and pasta. Net sales for the years ended September 30, 2020 and 2019 are presented under ASC Topic 606, “Revenue from Contracts with Customers,” and net sales for the year ended September 30, 2018 are presented under ASC Topic 605, “Revenue Recognition.” Note that additions to property and intangibles exclude additions through business acquisitions (see Note 4). Year Ended September 30, 2020 2019 2018 Net Sales Post Consumer Brands $ 1,949.1 $ 1,875.9 $ 1,831.7 Weetabix 440.4 418.2 423.4 Foodservice 1,361.8 1,627.4 1,548.2 Refrigerated Retail 961.2 907.3 790.9 BellRing Brands 988.3 854.4 827.5 Private Brands — — 848.9 Eliminations (2.1) (2.1) (13.4) Total $ 5,698.7 $ 5,681.1 $ 6,257.2 Segment Profit Post Consumer Brands $ 393.5 $ 337.1 $ 329.2 Weetabix 112.3 94.8 87.2 Foodservice 25.6 198.4 157.6 Refrigerated Retail 125.6 95.1 90.0 BellRing Brands 164.0 175.1 124.4 Private Brands — — 60.8 Total segment profit 821.0 900.5 849.2 General corporate expenses and other 109.0 169.6 136.8 Gain on sale of business — (126.6) — Impairment of goodwill and other intangibles — 63.3 124.9 Interest expense, net 388.6 322.4 387.3 Loss on extinguishment of debt, net 72.9 6.1 31.1 Expense (income) on swaps, net 187.1 306.6 (95.6) Earnings before income taxes and equity method loss $ 63.4 $ 159.1 $ 264.7 Net sales by product Cereal and granola $ 2,388.7 $ 2,293.3 $ 2,351.2 Eggs and egg products 1,307.8 1,578.4 1,542.8 Side dishes (including potato products) 536.6 519.6 398.2 Cheese and dairy 253.2 234.6 248.6 Sausage 168.1 149.6 96.0 Protein-based products and supplements 988.7 854.7 827.5 Nut butters and dried fruit and nut — — 487.5 Pasta — — 258.4 Other 57.3 52.5 53.0 Eliminations (1.7) (1.6) (6.0) Total $ 5,698.7 $ 5,681.1 $ 6,257.2 Additions to property and intangibles Post Consumer Brands $ 67.4 $ 62.1 $ 51.5 Weetabix 24.6 37.7 26.3 Foodservice and Refrigerated Retail 139.5 162.3 114.6 BellRing Brands 2.1 3.2 5.0 Private Brands — — 26.6 Corporate 1.0 8.6 1.0 Total $ 234.6 $ 273.9 $ 225.0 Depreciation and amortization Post Consumer Brands $ 112.4 $ 117.4 $ 122.0 Weetabix 35.9 35.0 38.1 Foodservice 119.6 111.8 105.4 Refrigerated Retail 73.1 74.1 57.9 BellRing Brands 25.3 25.3 25.9 Private Brands — — 40.9 Total segment depreciation and amortization 366.3 363.6 390.2 Corporate and accelerated depreciation 4.0 16.0 8.2 Total $ 370.3 $ 379.6 $ 398.4 September 30, 2020 2019 2018 Assets, end of year Post Consumer Brands $ 3,291.7 $ 3,296.3 $ 3,391.7 Weetabix 1,864.5 1,779.1 1,853.3 Foodservice and Refrigerated Retail 5,022.0 5,033.8 5,132.4 BellRing Brands 653.5 594.0 559.3 Private Brands — — 1,055.3 Corporate 1,315.0 1,248.4 1,065.5 Total $ 12,146.7 $ 11,951.6 $ 13,057.5

Quarterly Financial Information

Quarterly Financial Information	12 Months Ended
	Sep. 30, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	SUMMARY QUARTERLY FINANCIAL INFORMATION (UNAUDITED) First Second Third Fourth Quarter Quarter Quarter Quarter Fiscal 2020 Net sales $ 1,456.8 $ 1,494.2 $ 1,336.4 $ 1,411.3 Gross profit 471.5 438.8 436.8 440.3 Net earnings (loss) 99.2 (191.4) 36.0 57.0 Net earnings (loss) available to common shareholders 99.2 (191.4) 36.0 57.0 Basic earnings (loss) per share $ 1.40 $ (2.76) $ 0.53 $ 0.85 Diluted earnings (loss) per share $ 1.38 $ (2.76) $ 0.52 $ 0.83 Fiscal 2019 Net sales $ 1,411.3 $ 1,387.8 $ 1,439.2 $ 1,442.8 Gross profit 426.5 451.3 462.1 452.2 (Gain) loss on sale of business (124.7) (2.6) — 0.7 Impairment of goodwill and other intangible assets — — — 63.3 Net earnings (loss) 125.6 44.0 16.2 (61.1) Net earnings (loss) available to common shareholders 123.6 43.0 16.2 (61.1) Basic earnings (loss) per share $ 1.85 $ 0.61 $ 0.22 $ (0.84) Diluted earnings (loss) per share $ 1.67 $ 0.58 $ 0.21 $ (0.84)

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation — The consolidated financial statements include the operations of Post and its wholly-owned and majority-owned subsidiaries. All intercompany transactions have been eliminated.
Use of Estimates and Allocations	Use of Estimates and Allocations — The consolidated financial statements of the Company are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), which require certain elections as to accounting policy, estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent liabilities at the dates of the financial statements and the reported amount of net revenues and expenses during the reporting periods. Significant accounting policy elections, estimates and assumptions include, among others, pension and benefit plan assumptions, valuation assumptions of goodwill and other intangible assets, marketing programs, self-insurance reserves and income taxes. Actual results could differ from those estimates.
Business Combinations	Business Combinations — The Company uses the acquisition method in accounting for acquired businesses. Under the acquisition method, the Company’s financial statements reflect the operations of an acquired business starting from the completion of the acquisition. The assets acquired and liabilities assumed are recorded at their respective estimated fair values at the date of the acquisition. Any excess of the purchase price over the estimated fair values of the identifiable net assets acquired is recorded as goodwill. Any excess of the estimated fair values of the identifiable net assets over the purchase price is recorded as a gain on bargain purchase.
Cash Equivalents	Cash Equivalents — Cash equivalents include all highly liquid investments with original maturities of less than three months.
Restricted Cash	Restricted Cash — Restricted cash includes items such as cash deposits which serve as collateral for certain commodity hedging contracts as well as the Company’s high deductible workers’ compensation insurance program.
Receivables	Receivables — Receivables are reported at net realizable value. This value includes appropriate allowances for doubtful accounts, cash discounts and other amounts which the Company does not ultimately expect to collect. The Company determines its allowance for doubtful accounts based on historical losses as well as the economic status of and its relationship with its customers, especially those identified as “at risk.” A receivable is considered past due if payments have not been received within the agreed upon invoice terms. Receivables are written off against the allowance when the customer files for bankruptcy protection or are otherwise deemed to be uncollectible based upon the Company’s evaluation of the customer’s solvency.
Inventories	Inventories — Inventories, other than flocks, are generally valued at the lower of average cost (determined on a first-in, first-out basis) or net realizable value (“NRV”). Reported amounts have been reduced by an allowance for obsolete product and packaging materials based on a review of inventories on hand compared to estimated future usage and sales. Flock inventory represents the cost of purchasing and raising chicken flocks to egg laying maturity. The costs included in our flock inventory include the costs of the chicks, the feed fed to the birds and the labor and overhead costs incurred to operate the pullet facilities until the birds are transferred into the laying facilities, at which time their cost is amortized to operations, as cost of goods sold, over their expected useful lives of one to two years.
Restructuring Expenses	Restructuring Expenses — Restructuring charges principally consist of severance, accelerated stock compensation and other employee separation costs and accelerated depreciation. The Company recognizes restructuring obligations and liabilities for exit and disposal activities at fair value in the period the liability is incurred. Employee severance costs are expensed when they become probable and reasonably estimable under established severance plans. Depreciation expense related to assets that will be disposed of or idled as a part of the restructuring activity is accelerated through the expected date of the asset shut down. See Note 5 for information about restructuring expenses.
Property	Property — Property is recorded at cost, and depreciation expense is generally provided on a straight-line basis over the estimated useful lives of the properties. Estimated useful lives range from 1 to 29 years for machinery and equipment; 1 to 38 years for buildings, building improvements and leasehold improvements; and 1 to 7 years for software. Total depreciation expense was $209.6, $218.3 and $221.0 in fiscal 2020, 2019 and 2018, respectively. Any gains and losses incurred on the sale or disposal of assets are included in “Other operating expenses, net” in the Consolidated Statements of Operations. Repair and maintenance costs incurred in connection with ongoing and planned major maintenance activities are accounted for under the direct expensing method.
Other Intangible Assets	Other Intangible Assets — Other intangible assets consist primarily of customer relationships, trademarks and brands acquired in business combinations and include both indefinite and definite-lived assets.
Recoverability of Assets	Recoverability of Assets — The Company continually evaluates whether events or circumstances have occurred which might impair the recoverability of the carrying value of its assets, including property, identifiable intangibles, goodwill and right-of-use (“ROU”) assets. Trademarks with indefinite lives are reviewed for impairment during the fourth quarter of each fiscal year following the annual forecasting process, or more frequently if facts and circumstances indicate the trademark may be impaired. The trademark impairment tests require the Company to estimate the fair value of the trademark and compare it to its carrying value. The estimated fair value is determined using an income-based approach (the relief-from-royalty method), which requires significant assumptions for each brand, including estimates regarding future revenue growth, discount rates and royalty rates. Assumptions are determined after consideration of several factors for each brand, including profit levels, research of external royalty rates by third party experts and the relative importance of each brand to the Company. Revenue growth assumptions are based on historical trends and management’s expectations for future growth by brand. The discount rate is based on a weighted-average cost of capital utilizing industry market data of similar companies. In addition, definite-lived assets and indefinite-lived intangible assets are reassessed as needed when information becomes available that is believed to negatively impact the fair market value of an asset. In general, an asset is deemed impaired and written down to its fair value if estimated related future cash flows are less than its carrying amount. See Note 7 for information about goodwill impairments. For the year ended September 30, 2020, the Company conducted impairment reviews and concluded there was no impairment of other intangible assets as of September 30, 2020. At Septembe r 30, 2019, the Company recorded a definite-lived intangible impairment charge of $14.6 for the All Whites trademark in the Refrigerated Retail segment to adjust its carrying value to zero. The impairment charge for the All Whites trademark was the result of a strategic decision made by new Refrigerated Retail management in the fourth quarter of fiscal 2019 to discontinue use of the brand name. All products previously sold under the All Whites brand name are now being marketed and sold under the Bob Evans Egg Whites brand name. At September 30, 2018, the Company recorded an indefinite-lived intangible impairment charge of $124.9 for the Weetabix trademark to adjust its carrying value to its estimated fair value of $261.8. The impairment charge for the Weetabix trademark was a result of reduced branded cereal volumes related to Weetabix’s pricing reset and shifting consumer preferences to private label products.
Deferred Compensation Investments	Deferred Compensation Investments — The Company funds a portion of its deferred compensation liability by investing in certain mutual funds in the same amounts as selected by the participating employees. Because management’s intent is to invest in a manner that matches the deferral options chosen by the participants and those participants can elect to transfer amounts into or out of each of the designated deferral options at any time, these investments have been classified as trading assets and are stated at fair value in “Prepaid expenses and other current assets” and “Other assets” on the Consolidated Balance Sheets (see Note 15). Both realized and unrealized gains and losses on these assets are included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations and offset the related change in the deferred compensation liability.
Derivatives	Derivative Financial Instruments — In the ordinary course of business, the Company is exposed to commodity price risks relating to the acquisition of raw materials and supplies, interest rate risks relating to floating rate debt and foreign currency exchange rate risks. The Company utilizes derivative financial instruments, including (but not limited to) futures contracts, option contracts, forward contracts and swaps, to manage certain of these exposures by hedging when it is practical to do so. The Company does not hold or issue financial instruments for speculative or trading purposes. The Company’s derivative programs include strategies that qualify and strategies that do not qualify for hedge accounting treatment. To qualify for hedge accounting, the hedging relationship, both at inception of the hedge and on an ongoing basis, is expected to be highly effective in achieving offsetting changes in the fair value of the hedged risk during the period that the hedge is designated. All derivatives are recognized on the balance sheet at fair value. For derivatives that qualify for hedge accounting, the derivative is designated as a hedge on the date in which the derivative contract is entered. A derivative could be designated as a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge) or a hedge of a net investment in a foreign operation. Some derivatives may also be considered natural hedging instruments, where changes in their fair value act as economic offsets to changes in fair value of the underlying hedged item and are not designated for hedge accounting.
Revenue	Revenue — In conjunction with the adoption of ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” on October 1, 2018, the policy for recognizing revenue was updated. For fiscal 2020 and 2019, a summary of the policy for recognizing revenue was as follows: The Company recognizes revenue when performance obligations have been satisfied by transferring control of the goods to customers. Control is generally transferred upon delivery of the goods to the customer. At the time of delivery, the customer is invoiced using previously agreed-upon credit terms. Shipping and/or handling costs that occur before the customer obtains control of the goods are deemed fulfillment activities and are accounted for as fulfillment costs. The Company’s contracts with customers generally contain one performance obligation. Many of the Company’s contracts with customers include some form of variable consideration. The most common forms of variable consideration are trade promotions, rebates and discounts. Variable consideration is treated as a reduction of revenue at the time product revenue is recognized. Depending on the nature of the variable consideration, the Company uses either the “expected value” or the “most likely amount” method to determine variable consideration. The Company does not believe that there will be significant changes to its estimates of variable consideration when any uncertainties are resolved with customers. The Company reviews and updates estimates of variable consideration quarterly. Uncertainties related to the estimates of variable consideration are resolved in a short time frame and do not require any additional constraint on variable consideration. The Company’s products are sold with no right of return, except in the case of goods which do not meet product specifications or are damaged. No services beyond this assurance-type warranty are provided to customers. Customer remedies include either a cash refund or an exchange of the product. As a result, the right of return and related refund liability is estimated and recorded as a reduction of revenue based on historical sales return experience. For fiscal 2018, a summary of the policy for recognizing revenue was as follows: Revenue is recognized when title of goods and risk of loss is transferred to the customer, as specified by the shipping terms. Net sales reflect gross sales, including amounts billed to customers for shipping and handling, less sales discounts and trade allowances (including promotional price buy downs and new item promotional funding). Customer trade allowances are generally computed as a percentage of gross sales. Products are generally sold with no right of return, except in the case of goods which do not meet product specifications or are damaged, and related reserves are maintained based on return history. If additional rights of return are granted, revenue recognition is deferred. Estimated reductions to revenue for customer incentive offerings are based upon customer redemption history.
Cost of Good Sold	Cost of Goods Sold —
Advertising	Advertising —
Stock-Based Compensation	Stock-based Compensation — The Company recognizes the cost of employee services received in exchange for awards of equity instruments based on the grant-date fair value of equity awards and the fair market value at each quarterly reporting date for liability awards. That cost is recognized over the period during which an employee is required to provide service in exchange for the award — the requisite service period (usually the vesting period). Any forfeitures of stock-based awards are recorded as they occur. See Note 20 for disclosures related to stock-based compensation.
Income Tax (Benefit) Expense	Income Taxes — Income tax expense (benefit) is estimated based on income taxes in each jurisdiction and includes the effects of both current tax exposures and the temporary differences resulting from differing treatment of items for tax and financial reporting purposes. These temporary differences result in deferred tax assets and liabilities. A valuation allowance is

Leases (Policies)

Leases (Policies)	12 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	The Company determines if an arrangement is a lease at its inception. When the arrangements include lease and non-lease components, the Company accounts for them as a single lease component. Leases with an initial term of less than 12 months are not reported on the balance sheet, but rather are recognized as lease expense on a straight-line basis over the lease term. Arrangements may include options to extend or terminate the lease arrangement. These options are included in the lease term used to establish ROU assets and lease liabilities when it is reasonably certain they will be exercised. The Company will reassess expected lease terms based on changes in circumstances that indicate options may be more or less likely to be exercised. The Company has certain lease arrangements that include variable rental payments. The future variability of these payments and adjustments are unknown and therefore are not included in minimum rental payments used to determine ROU assets and lease liabilities. The Company has lease arrangements where it makes separate payments to the lessor based on the lessor’s common area maintenance expenses, property and casualty insurance costs, property taxes assessed on the property and other variable expenses. As the Company has elected the practical expedient not to separate lease and non-lease components, these variable amounts are captured in operating lease expense in the period in which they are incurred. Variable rental payments are recognized in the period in which their associated obligation is incurred. As most of the Company’s lease arrangements do not provide an implicit interest rate, an incremental borrowing rate (“IBR”) is applied in determining the present value of future payments. The Company’s IBR is selected based upon information available at the lease commencement date.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Property	September 30, 2020 2019 Land and land improvements $ 93.1 $ 91.1 Buildings and leasehold improvements 880.5 796.7 Machinery and equipment 1,766.8 1,595.8 Software 111.4 106.0 Construction in progress 127.4 147.3 2,979.2 2,736.9 Accumulated depreciation (1,199.5) (1,000.9) $ 1,779.7 $ 1,736.0
Other intangible assets	September 30, 2020 September 30, 2019 Carrying Accum. Net Carrying Accum. Net Subject to amortization: Customer relationships $ 2,304.8 $ (681.9) $ 1,622.9 $ 2,297.2 $ (562.2) $ 1,735.0 Trademarks and brands 795.0 (266.9) 528.1 793.7 (225.2) 568.5 Other 3.1 (3.1) — 3.1 (3.1) — 3,102.9 (951.9) 2,151.0 3,094.0 (790.5) 2,303.5 Not subject to amortization: Trademarks and brands 1,046.5 — 1,046.5 1,035.0 — 1,035.0 $ 4,149.4 $ (951.9) $ 3,197.5 $ 4,129.0 $ (790.5) $ 3,338.5
Impact of Adopting ASC 606	Year Ended September 30, 2019 As Reported Under Topic 606 As Reported Under Prior Guidance Impact of Adoption Net Sales $ 5,681.1 $ 5,706.0 $ (24.9) Cost of goods sold 3,889.0 3,889.0 — Gross Profit 1,792.1 1,817.0 (24.9) Selling, general and administrative expenses 911.6 937.7 (26.1) Amortization of intangible assets 161.3 161.3 — Gain on sale of business (126.6) (126.6) — Impairment of goodwill and other intangible assets 63.3 63.3 — Other operating expenses, net 1.5 1.5 — Operating Profit $ 781.0 $ 779.8 $ 1.2

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Sep. 30, 2020
Business Acquisition
Pro Forma Information	2018 Pro forma net sales $ 6,423.8 Pro forma net earnings available to common shareholders $ 486.4 Pro forma basic earnings per share $ 7.30 Pro forma diluted earnings per share $ 6.54
Bob Evans Farms Opening Balance Sheet with Measurement Period Adjustments
Business Acquisition
Schedule of Business Combinations, Measurement Period Adjustments	Acquisition Date Amounts Recognized as of September 30, 2018 (a) Adjustments During Fiscal 2019 Acquisition Date Amounts Recognized (as Adjusted) Cash and cash equivalents $ 15.6 $ — $ 15.6 Receivables 58.5 — 58.5 Inventories 27.1 — 27.1 Prepaid expenses and other current assets 34.3 — 34.3 Property 184.3 — 184.3 Goodwill 898.3 (0.7) 897.6 Other intangible assets 782.0 — 782.0 Other assets 0.4 — 0.4 Accounts payable (18.2) — (18.2) Other current liabilities (58.5) — (58.5) Deferred tax liability - long-term (194.9) 0.7 (194.2) Other liabilities (5.3) — (5.3) Total acquisition cost (b) $ 1,723.6 $ — $ 1,723.6 (a) As previously reported in Post’s Annual Report on Form 10-K for fiscal 2018 filed with the Securities and Exchange Commission (the “SEC”) on November 16, 2018. (b) Total acquisition cost is comprised of $1,381.2 paid at closing and additional payments of $342.4, which includes payments to former holders of shares of Bob Evans common stock who exercised appraisal rights, payments in connection with Bob Evans deferred compensation plans and payments to compensate Bob Evans employees due to the cancellation of their outstanding employee stock awards.

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Sep. 30, 2020
Restructuring and Related Activities [Abstract]
Schedule of Restructuring and Related Costs	Employee-Related Costs Accelerated Depreciation Total Balance, September 30, 2017 $ — $ — $ — Charge to expense 2.7 2.5 5.2 Non-cash charges — (2.5) (2.5) Balance, September 30, 2018 $ 2.7 $ — $ 2.7 Charge to expense 2.2 7.4 9.6 Cash payments (4.8) — (4.8) Non-cash charges — (7.4) (7.4) Balance, September 30, 2019 $ 0.1 $ — $ 0.1 Cash payments (0.1) — (0.1) Balance, September 30, 2020 $ — $ — $ — Total expected restructuring charge $ 4.9 $ 9.9 $ 14.8 Cumulative incurred to date 4.9 9.9 14.8 Remaining expected restructuring charge $ — $ — $ —

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Carrying Amount of Goodwill	Post Consumer Brands Weetabix Foodservice Refrigerated Retail BellRing Brands Total Balance, September 30, 2018 Goodwill (gross) $ 2,012.0 $ 900.9 $ 1,336.1 $ 793.8 $ 180.7 $ 5,223.5 Accumulated impairment losses (609.1) — — — (114.8) (723.9) Goodwill (net) $ 1,402.9 $ 900.9 $ 1,336.1 $ 793.8 $ 65.9 $ 4,499.6 Impairment loss — — — (48.7) — (48.7) Acquisition related adjustment — — (0.5) (0.2) — (0.7) Currency translation adjustment (0.2) (50.2) — — — (50.4) Balance, September 30, 2019 Goodwill (gross) $ 2,011.8 $ 850.7 $ 1,335.6 $ 793.6 $ 180.7 $ 5,172.4 Accumulated impairment losses (609.1) — — (48.7) (114.8) (772.6) Goodwill (net) $ 1,402.7 $ 850.7 $ 1,335.6 $ 744.9 $ 65.9 $ 4,399.8 Currency translation adjustment — 38.8 — — — 38.8 Balance, September 30, 2020 Goodwill (gross) $ 2,011.8 $ 889.5 $ 1,335.6 $ 793.6 $ 180.7 $ 5,211.2 Accumulated impairment losses (609.1) — — (48.7) (114.8) (772.6) Goodwill (net) $ 1,402.7 $ 889.5 $ 1,335.6 $ 744.9 $ 65.9 $ 4,438.6

Noncontrolling Interests, Equ_2

Noncontrolling Interests, Equity Interests and Related Party Transactions (Tables)	12 Months Ended
	Sep. 30, 2020
Schedule of Equity Method Investments [Line Items]
Effects of changes in ownership of BellRing on Post equity	Year Ended September 30, 2020 Increase in additional paid-in capital related to net proceeds from IPO $ 524.4 Increase in additional paid-in capital related to establishment of noncontrolling interest 65.0 Decrease in additional paid-in capital related to tax effects of IPO (133.8) Net transfers from noncontrolling interest $ 455.6
Equity Method Loss Attributable to 8th Avenue	Year Ended September 30, 2020 2019 8th Avenue’s net loss available to 8th Avenue’s common shareholders $ (38.9) $ (46.7) 60.5 % 60.5 % Equity method loss available to Post $ (23.5) $ (28.3) Less: Amortization of basis difference, net of tax (a) 6.9 8.8 Equity method loss, net of tax $ (30.4) $ (37.1) (a) The Company adjusted the historical basis of 8th Avenue’s assets and liabilities to fair value and recognized a total basis difference of $70.3. The basis difference related to inventory of $2.0 , net of tax, was included in equity method loss in the year ended September 30, 2019. The basis difference related to property, plant and equipment and other intangible assets is being amortized over the weighted average useful lives of the assets. At September 30, 2020 and 2019, the remaining basis difference to be amortized was $54.6 and $61.5, respectively
8th Avenue Summarized Financial Information	Year Ended September 30, 2020 2019 Net sales $ 924.2 $ 838.5 Gross profit $ 160.0 $ 139.6 Net loss $ (6.4) $ (17.6) Less: Preferred stock dividend 32.5 29.1 Net Loss Available to 8th Avenue Common Shareholders $ (38.9) $ (46.7) Year Ended September 30, 2020 2019 Current assets $ 251.5 $ 209.2 Other assets 830.1 826.2 Total Assets $ 1,081.6 $ 1,035.4 Current portion of long-term debt $ 5.2 $ 5.2 Accounts payable and other current liabilities 113.3 74.4 Long-term debt 663.3 644.9 Other liabilities 71.6 76.5 Total Liabilities 853.4 801.0 Preferred stock 61.6 29.1 Other shareholders’ equity 166.6 205.3 Shareholders’ Equity 228.2 234.4 Total Liabilities and Shareholders’ Equity $ 1,081.6 $ 1,035.4

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Components of Earnings (Loss) before Income Taxes and Equity Method Loss	Year Ended September 30, 2020 2019 2018 Domestic $ (36.4) $ 80.4 $ 289.0 Foreign 99.8 78.7 (24.3) Earnings before Income Taxes and Equity Method Loss $ 63.4 $ 159.1 $ 264.7 Income tax expense (benefit) $ 3.5 $ (3.9) $ (204.0) Effective income tax rate 5.5 % (2.5) % (77.1) %
Reconciliation of expense (benefit) for Income Taxes	Year Ended September 30, 2020 2019 2018 Current: Federal $ 31.3 $ 61.5 $ 27.3 State 7.1 2.6 5.2 Foreign 8.7 12.3 20.0 47.1 76.4 52.5 Deferred: Federal (45.6) (61.8) (253.5) State (14.5) (15.2) 21.4 Foreign 16.5 (3.3) (24.4) (43.6) (80.3) (256.5) Income tax expense (benefit) $ 3.5 $ (3.9) $ (204.0)
Reconciliation of Income Tax expense (benefit)	Year Ended September 30, 2020 2019 2018 Computed tax (a) $ 13.3 $ 33.4 $ 64.9 Enacted tax law and changes, including the Tax Act (a) (1.5) (4.8) (270.9) Non-deductible goodwill impairment loss — 6.9 — Non-deductible compensation 4.5 2.7 1.2 Transaction costs (1.1) 2.2 1.5 Domestic production activities deduction — — (5.9) State income tax (benefit) expense, net of effect on federal tax (4.3) (0.7) 5.6 Non-taxable interest income — — (2.4) Valuation allowances 5.0 6.6 4.1 Change in deferred tax rates 11.1 (4.6) 0.3 Uncertain tax positions 1.2 (7.9) 0.3 Net losses and basis difference attributable to equity method investment (6.5) 4.4 — Income tax credits (2.6) (3.0) (2.3) Rate differential on foreign income (10.8) (7.7) (5.3) Excess tax benefits for share-based payments (1.4) (33.4) (1.8) Gain on bargain purchase (2.5) — — Enhanced deduction for food donation (1.5) (0.6) (0.8) Return-to-provision (1.5) 0.6 (1.0) Other, net (none in excess of 5% of statutory tax) 2.1 2.0 8.5 Income tax expense (benefit) $ 3.5 $ (3.9) $ (204.0)
Deferred tax assets (liabilities)	September 30, 2020 September 30, 2019 Assets Liabilities Net Assets Liabilities Net Derivative mark-to-market adjustments $ 133.8 $ — $ 133.8 $ 98.5 $ — $ 98.5 Disallowed interest carryforwards 36.0 — 36.0 29.7 — 29.7 Net operating loss and credit carryforwards 33.7 — 33.7 30.8 — 30.8 Lease liabilities 26.2 — 26.2 — — — Stock-based and deferred compensation 18.4 — 18.4 19.9 — 19.9 Accrued vacation, incentive and severance 8.3 — 8.3 7.7 — 7.7 Accrued liabilities 9.0 — 9.0 15.6 — 15.6 Inventory 3.2 — 3.2 6.2 — 6.2 Intangible assets — (619.9) (619.9) — (652.4) (652.4) Property — (192.3) (192.3) — (173.4) (173.4) Investment in partnership (a) — (144.6) (144.6) — — — ROU assets — (25.5) (25.5) — — — Basis difference attributable to equity method investment — (22.5) (22.5) — (30.0) (30.0) Pension and other postretirement benefits — (10.1) (10.1) — (11.2) (11.2) Other items 4.6 (1.7) 2.9 4.5 (1.8) 2.7 Total gross deferred income taxes 273.2 (1,016.6) (743.4) 212.9 (868.8) (655.9) Valuation allowance (41.1) — (41.1) (32.6) — (32.6) Total deferred taxes $ 232.1 $ (1,016.6) $ (784.5) $ 180.3 $ (868.8) $ (688.5) (a) The Company’s deferred tax liability for investment in partnership relates to excess financial reporting outside basis over tax outside basis in BellRing entities treated as partnerships for U.S. federal income tax purposes.
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	September 30, 2020 2019 2018 Balance, beginning of year $ 8.6 $ 9.9 $ 8.6 Additions for tax positions taken in current year and acquisitions 1.7 0.1 2.0 Additions (reductions) for tax positions taken in prior years — 5.7 (0.1) Held for sale liabilities — — (0.6) Settlements with tax authorities/statute expirations (0.5) (7.1) — Balance, end of year $ 9.8 $ 8.6 $ 9.9

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Year ended September 30, 2020 2019 2018 Net earnings for basic earnings per share $ 0.8 $ 121.7 $ 457.3 Dilutive impact of BellRing net earnings — — — Dilutive preferred stock dividends — 3.0 10.0 Net earnings for diluted earnings per share $ 0.8 $ 124.7 $ 467.3 Weighted-average shares for basic earnings per share 68.9 70.8 66.6 Effect of dilutive securities: Stock options 0.6 1.6 1.8 Stock appreciation rights 0.1 0.1 0.1 Restricted stock units 0.4 0.5 0.4 Performance-based restricted stock units 0.1 — — Preferred shares conversion to common — 2.1 7.0 Total dilutive securities 1.2 4.3 9.3 Weighted-average shares for diluted earnings per share 70.1 75.1 75.9 Basic earnings per common share $ 0.01 $ 1.72 $ 6.87 Diluted earnings per common share $ 0.01 $ 1.66 $ 6.16
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Year ended September 30, 2020 2019 2018 Stock options 0.1 0.1 0.6 Restricted stock units — — 0.1 Performance-based restricted stock units 0.1 — —

Supplemental Operations State_2

Supplemental Operations Statement and Cash Flow Information (Tables)	12 Months Ended
	Sep. 30, 2020
Supplemental Operations Statement and Cash Flow Information [Abstract]
Supplemental Operations Statement and Cash Flow Information	Year Ended September 30, 2020 2019 2018 Advertising and promotion expenses (a) $ 146.0 $ 122.3 $ 153.4 Repair and maintenance expenses 140.0 156.9 149.1 Research and development expenses 28.5 25.0 25.1 Interest income (6.3) (7.9) (7.4) Interest paid 348.8 344.4 373.9 Income taxes paid 54.4 65.0 23.0 Accrued additions to property 29.8 24.7 30.4 (a) As a result of the adoption of ASU 2014-09, certain payments to customers totaling $23.7 in the year ended September 30, 2019 previously classified as advertising and promotion expenses were classified as net sales. For additional information, see Note 2.

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Sep. 30, 2020
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	September 30, 2020 2019 Receivables, net Trade $ 395.4 $ 407.8 Income tax receivable 26.6 21.9 Related party 3.2 5.1 Other 19.8 12.3 445.0 447.1 Allowance for doubtful accounts (3.4) (2.0) $ 441.6 $ 445.1 Inventories Raw materials and supplies $ 118.1 $ 99.4 Work in process 17.8 19.4 Finished products 429.4 425.4 Flocks 34.1 35.6 $ 599.4 $ 579.8 Other Assets Pension asset $ 159.0 $ 166.7 Operating ROU Assets 116.3 — Equity securities 27.9 — Other 25.8 38.8 $ 329.0 $ 205.5 Accounts Payable Trade $ 357.6 $ 349.6 Book cash overdrafts 0.7 35.1 Other 9.6 10.9 $ 367.9 $ 395.6 Other Current Liabilities Advertising and promotion $ 44.9 $ 45.2 Accrued interest 85.9 46.0 Accrued compensation 98.5 85.3 Hedging liabilities 187.9 87.6 Operating lease liabilities - current 23.6 — Accrued legal settlements 13.2 16.1 Accrued appraisal rights and related interest — 19.1 Other 87.6 94.5 $ 541.6 $ 393.8 Other Liabilities Pension and other postretirement benefit obligations $ 77.7 $ 66.0 Hedging liabilities - non-current 355.2 330.5 Accrued compensation - non-current 30.2 34.0 Operating lease liabilities - non-current 103.0 — Other 33.7 26.4 $ 599.8 $ 456.9

Allowance for Doubtful Accoun_2

Allowance for Doubtful Accounts (Tables)	12 Months Ended
	Sep. 30, 2020
Allowance for Doubtful Accounts [Abstract]
Allowance for Doubtful Accounts	September 30, 2020 2019 2018 Balance, beginning of year $ 2.0 $ 2.3 $ 1.6 Provision charged to expense 3.3 0.1 0.1 Write-offs, less recoveries (1.9) (0.4) (1.2) Held for sale assets — — (0.5) Other (a) — — 2.3 Balance, end of year $ 3.4 $ 2.0 $ 2.3 (a) Other items are primarily related to acquisitions.

Derivative Financial Instrume_2

Derivative Financial Instruments and Hedging (Tables)	12 Months Ended
	Sep. 30, 2020
Derivative [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions	September 30, September 30, Not designated as hedging instruments under ASC Topic 815: Commodity contracts $ 24.7 $ 47.1 Energy contracts 87.1 39.8 Foreign exchange contracts - Forward contracts 28.9 — Interest rate swap 621.7 73.1 Interest rate swaps - Rate-lock swaps 1,666.0 1,531.0 Interest rate swaps - Options 433.3 — Designated as hedging instruments under ASC Topic 815: Foreign exchange contracts - Cross-currency swaps — 448.7 Interest rate swap — 200.0
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Fair Value Portion Designated as Hedging Instruments Balance Sheet Location September 30, September 30, September 30, September 30, Asset Derivatives: Commodity contracts Prepaid expenses and other current assets $ 5.0 $ 1.9 $ — $ — Energy contracts Prepaid expenses and other current assets 1.8 0.7 — — Commodity contracts Other assets 0.1 0.1 — — Energy contracts Other assets 0.9 — — — Foreign exchange contracts Prepaid expenses and other current assets 0.1 1.3 — 1.3 Foreign exchange contracts Other assets — 19.2 — 19.2 Interest rate swaps Prepaid expenses and other current assets 6.8 — — — $ 14.7 $ 23.2 $ — $ 20.5 Liability Derivatives: Commodity contracts Other current liabilities $ 1.4 $ 1.0 $ — $ — Energy contracts Other current liabilities 10.1 1.5 — — Energy contracts Other liabilities 3.9 0.1 — — Interest rate swaps Other current liabilities 176.4 85.1 — 1.6 Interest rate swaps Other liabilities 351.3 330.4 — 6.2 $ 543.1 $ 418.1 $ — $ 7.8
Schedule of Derivative Instruments, Loss (Gain) in Statement of Financial Performance	Derivatives Not Designated as Hedging Instruments Statement of Operations Location Loss (Gain) Recognized in Statement of Operations 2020 2019 2018 Commodity contracts Cost of goods sold $ 3.8 $ 2.8 $ 4.0 Energy contracts Cost of goods sold 21.6 5.0 (6.4) Foreign exchange contracts Selling, general and administrative expenses (0.1) — 1.5 Interest rate swaps Interest expense, net 3.0 — — Interest rate swaps Expense (income) on swaps, net 187.1 306.6 (95.6) Derivatives Designated as Hedging Instruments Loss (Gain) Recognized in OCI including NCI Loss (Gain) Reclassified from Accumulated OCI including NCI into Earnings (a) Statement of Operations Location 2020 2019 2018 2020 2019 2018 Foreign exchange contracts $ — $ — $ (0.2) $ — $ — $ (1.3) Selling, general and administrative expenses Interest rate swaps 9.7 13.8 (44.2) 8.2 (31.0) (2.3) Interest expense, net Cross-currency swaps (32.2) (54.3) (27.8) — — — Expense (income) on swaps, net (a) For the year ended September 30, 2020, this amount includes the reclassification of previously unrealized net losses on interest rate swaps that were de-designated as hedging instruments in the first quarter of fiscal 2020, as well as the amortization of previously unrealized losses on BellRing’s interest rate swaps that were de-designated as hedging instruments as of April 1, 2020.
Net Hedging Losses (Gains) on Interest Rate Swaps	The following table presents the components of the Company’s net hedging losses (gains) on interest rate swaps, which are included in “Interest expense, net” and “Expense on swaps, net” in the Consolidated Statements of Operations. Year Ended Statement of Operations Location Mark-to-Market Loss (a) Cash Settlements Paid (Received), Net (b) Net Loss Reclassified from Accumulated OCI including NCI (c) Interest expense, net $ (0.2) $ 1.8 $ 8.4 Expense on swaps, net 117.4 69.7 — 2020 Total $ 117.2 $ 71.5 $ 8.4 Interest expense, net $ — $ (31.0) $ — Expense on swaps, net 293.1 13.5 — 2019 Total $ 293.1 $ (17.5) $ — Interest expense, net $ — $ (2.3) $ — Expense on swaps, net (96.7) 1.1 — 2018 Total $ (96.7) $ (1.2) $ — (a) Includes non-cash adjustments related to interest rate swaps that were not designated as hedging instruments. (b) Includes cash settlements recognized in earnings related to interest rate swaps that were not designated as hedging instruments and cash settlements reclassified from accumulated OCI into earnings related to interest rate swaps that had been previously designated as hedging instruments. (c) Includes the reclassification of previously unrealized losses on interest rate swaps that were de-designated as hedging instruments, as well as the amortization of previously unrealized losses on BellRing’s interest rate swaps over the term of the related debt that were de-designated as hedging instruments.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	September 30, 2020 September 30, 2019 Total Level 1 Level 2 Total Level 1 Level 2 Assets Deferred compensation investment $ 12.8 $ 12.8 $ — $ 11.2 $ 11.2 $ — Derivative assets 14.7 — 14.7 23.2 — 23.2 Equity securities 27.9 27.9 — — — — $ 55.4 $ 40.7 $ 14.7 $ 34.4 $ 11.2 $ 23.2 Liabilities Deferred compensation liabilities $ 29.7 $ — $ 29.7 $ 31.0 $ — $ 31.0 Derivative liabilities 543.1 — 543.1 418.1 — 418.1 $ 572.8 $ — $ 572.8 $ 449.1 $ — $ 449.1
Fair Value Measurements, Nonrecurring	Balance, September 30, 2018 $ 290.9 Gains related to assets and liabilities held for sale 124.6 Proceeds from the sale of assets and liabilities held for sale (276.6) Investment in 8th Avenue, working capital and other adjustments (138.9) Transfers of assets into held for sale 9.9 Balance, September 30, 2019 $ 9.9 Losses related to assets held for sale (2.7) Proceeds from the sale of assets held for sale (2.4) Transfer of assets into held for sale 2.5 Balance, September 30, 2020 $ 7.3

Leases (Tables)

Leases (Tables)	12 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Balance Sheet location of Operating Leases	September 30, 2020 ROU assets: Other assets $ 116.3 Lease liabilities: Other current liabilities $ 23.6 Other liabilities 103.0 Total lease liabilities $ 126.6
Maturities of Lease Liabilities, under ASC Topic 842	September 30, 2020 Fiscal 2021 $ 28.7 Fiscal 2022 27.7 Fiscal 2023 24.4 Fiscal 2024 17.7 Fiscal 2025 11.9 Thereafter 39.9 Total future minimum payments $ 150.3 Less: Implied interest 23.7 Total lease liabilities $ 126.6
Future Minimum Rental Payments, under ASC Topic 840	September 30, Fiscal 2020 $ 28.3 Fiscal 2021 29.0 Fiscal 2022 28.1 Fiscal 2023 25.4 Fiscal 2024 19.2 Thereafter 77.3 Total future minimum payments (a) $ 207.3 (a) Future minimum payments as of September 30, 2019 included $36.0 related to a real estate lease, consisting of land and a building, that was purchased by the Company in December 2019 and the Company de-recognized both a ROU asset and lease liability of $23.1 and recognized the assets as property on the balance sheet.

Long Term Debt (Tables)

Long Term Debt (Tables)	12 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	September 30, 2020 2019 4.625% Senior Notes maturing April 2030 $ 1,650.0 $ — 5.50% Senior Notes maturing December 2029 750.0 750.0 5.625% Senior Notes maturing January 2028 940.9 940.9 5.50% Senior Notes maturing March 2025 — 1,000.0 5.75% Senior Notes maturing March 2027 1,299.3 1,299.3 5.00% Senior Notes maturing August 2026 1,697.3 1,697.3 8.00% Senior Notes maturing July 2025 — 122.2 Term Loan — 1,309.5 BellRing Term B Facility 673.7 — BellRing Revolving Credit Facility 30.0 — Municipal bond 8.5 — Capital lease — 0.1 7,049.7 7,119.3 Less: Current Portion 64.9 13.5 Debt issuance costs, net 62.6 69.0 Plus: Unamortized premium 36.8 29.2 Total long-term debt $ 6,959.0 $ 7,066.0
Repayments of Long-Term Debt	The following table shows the Company’s repayments of long-term debt and associated gain or loss included in “Loss on extinguishment of debt, net” in the Consolidated Statements of Operations. Repayments of Long-Term Debt Loss on Extinguishment of Debt, net Year Ended Issuance Principal Amount Repaid Debt Repurchased at a Discount Premium and Debt Extinguishment Costs Paid Write-off of Debt Issuance Costs Write-off of Unamortized Premium Term Loan $ 1,309.5 $ — $ — $ 9.1 $ — 2020 Bridge Loan 1,225.0 — — 3.8 — 5.50% Senior Notes maturing in March 2025 1,000.0 — 41.3 8.7 — Revolving Credit Facility 500.0 — — — — BellRing Revolving Credit Facility 165.0 — — — — 8.00% Senior Notes 122.2 — 8.5 0.7 — BellRing Term B Facility 26.3 — — — — Municipal bond 1.1 — — — — Second AR Credit Agreement — — — 0.8 — 2020 Total $ 4,349.1 $ — $ 49.8 $ 23.1 $ — Term Loan $ 863.0 $ — $ — $ 7.6 $ — 5.75% Senior Notes 27.0 (1.5) — 0.3 (0.7) 5.625% Senior Notes 20.0 (1.3) — 0.2 — 5.00% Senior Notes 13.0 (1.2) — 0.1 — Capital lease 0.1 — — — — 2018 Bridge Loan (a) — — — 2.6 — 2019 Total $ 923.1 $ (4.0) $ — $ 10.8 $ (0.7) 6.00% Senior Notes $ 630.0 $ — $ 30.8 $ 6.5 $ — 5.625% Senior Notes 39.1 (2.1) — 0.4 — 5.75% Senior Notes 173.7 (3.1) — 1.9 (4.6) 5.00% Senior Notes 39.7 (2.5) — 0.4 — 8.00% Senior Notes 15.3 — 2.0 0.1 — Term Loan (b) 22.0 — 0.9 0.4 — 2018 Total $ 919.8 $ (7.7) $ 33.7 $ 9.7 $ (4.6) (a) In connection with the assumption of the 2018 Bridge Loan by 8th Avenue discussed above, the Company recorded a write-off of debt issuance costs during the year ended September 30, 2019 for costs that were not refunded upon the closing of the 8th Avenue Transactions.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Sep. 30, 2020
Defined Benefit Plan Disclosure
Schedule of change in projected benefit obligation, change in fair value of plan assets, and net funded status	The following table provides a reconciliation of the changes in the pension plans’ benefit obligations and fair value of assets over the two year period ended September 30, 2020 and a statement of the funded status and amounts recognized on the Consolidated Balance Sheets as of September 30, 2020 and 2019. North America Other International Year Ended Year Ended 2020 2019 2020 2019 Change in benefit obligation Benefit obligation at beginning of period $ 121.5 $ 100.9 $ 780.5 $ 691.2 Service cost 4.3 3.7 — 5.6 Interest cost 3.7 4.1 14.7 18.9 Plan participants’ contributions 0.5 0.5 — 2.2 Prior service cost (a) — — 11.4 1.5 Actuarial loss 6.6 17.3 17.6 126.6 Benefits paid (5.4) (4.6) (25.9) (26.2) Currency translation (0.1) (0.4) 36.1 (39.3) Benefit obligation at end of period $ 131.1 $ 121.5 $ 834.4 $ 780.5 Change in fair value of plan assets Fair value of plan assets at beginning of period $ 119.7 $ 114.1 $ 946.9 $ 844.5 Actual return on plan assets 6.4 9.8 28.1 169.9 Employer contributions 0.4 0.3 — 4.8 Plan participants’ contributions 0.5 0.5 — 2.2 Benefits paid (5.4) (4.6) (25.9) (26.2) Currency translation (0.1) (0.4) 44.1 (48.3) Fair value of plan assets at end of period 121.5 119.7 993.2 946.9 Funded status $ (9.6) $ (1.8) $ 158.8 $ 166.4 Amounts recognized in assets or liabilities Other assets $ 0.2 $ 0.3 $ 158.8 $ 166.4 Other liabilities (9.8) (2.1) — — Net amount recognized $ (9.6) $ (1.8) $ 158.8 $ 166.4 Amounts recognized in accumulated other comprehensive loss Net actuarial loss (gain) $ 28.2 $ 23.4 $ (32.3) $ (46.5) Prior service cost 0.3 0.4 11.5 0.1 Total $ 28.5 $ 23.8 $ (20.8) $ (46.4) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 3.01 % 3.32 % n/a n/a Discount rate — Canadian plans 2.71 % 2.84 % n/a n/a Discount rate — Other international plans n/a n/a 1.73 % 1.84 % Rate of compensation increase — U.S. plans 3.00 % 3.00 % n/a n/a Rate of compensation increase — Canadian plans 2.75 % 2.75 % n/a n/a Rate of compensation increase — Other international plans n/a n/a 2.65 % 2.55 % (a) During the year ended September 30, 2020, the Company recognized prior service cost as a result of an amendment to the benefit plan for Weetabix employees in the U.K. participating in the group scheme. During the year ended September 30, 2019, the Company recognized prior service cost as a result of U.K. high court rulings made in connection with the Guaranteed Minimum Pension (the “GMP”). The following table provides a reconciliation of the changes in the North American other postretirement benefit obligations over the two year period ended September 30, 2020. Besides the North American plans, the Company does not maintain any other postretirement benefit plans. Year Ended 2020 2019 Change in benefit obligation Benefit obligation at beginning of period $ 66.4 $ 55.2 Service cost 0.6 0.4 Interest cost 1.9 2.1 Actuarial loss 4.6 11.5 Benefits paid (2.7) (2.6) Currency translation (0.1) (0.2) Benefit obligation at end of period $ 70.7 $ 66.4 Change in fair value of plan assets Employer contributions 2.7 2.6 Benefits paid (2.7) (2.6) Fair value of plan assets at end of period — — Funded status $ (70.7) $ (66.4) Amounts recognized in assets or liabilities Other current liabilities (2.8) (2.5) Other liabilities (67.9) (63.9) Net amount recognized $ (70.7) $ (66.4) Amounts recognized in accumulated other comprehensive loss Net actuarial loss $ 14.3 $ 10.3 Prior service credit (14.7) (19.4) Total $ (0.4) $ (9.1) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 2.79 % 3.20 % Discount rate — Canadian plans 2.78 % 2.86 % Rate of compensation increase — Canadian plans 2.75 % 2.75 %
Pension plan's assets measured at fair value on a recurring basis	North America September 30, 2020 September 30, 2019 Total Level 1 Level 2 Total Level 1 Level 2 Equities $ 10.5 $ — $ 10.5 $ 9.9 $ — $ 9.9 Fixed income and bonds 5.5 — 5.5 5.3 — 5.3 Cash and cash equivalents 1.3 1.3 — 1.2 1.2 — Fair value of plan assets in the fair value hierarchy 17.3 1.3 16.0 16.4 1.2 15.2 Equities 60.3 — — 45.6 — — Fixed income and bonds 43.8 — — 51.3 — — Real assets 0.1 — — 6.4 — — Investments measured at net asset value (a) 104.2 — — 103.3 — — Total plan assets $ 121.5 $ 1.3 $ 16.0 $ 119.7 $ 1.2 $ 15.2 Other International September 30, 2020 September 30, 2019 Total Level 1 Level 2 Total Level 1 Level 2 Fixed income and bonds $ 642.1 $ 642.1 $ — $ 554.8 $ 554.8 $ — Liability driven instruments 241.6 241.6 — 258.6 258.6 — Cash and cash equivalents 16.1 16.1 — 51.3 51.3 — Fair value of plan assets in the fair value hierarchy 899.8 899.8 — 864.7 864.7 — Fixed income and bonds 49.2 — — 37.0 — — Liability driven instruments 28.6 — — 26.0 — — Real assets 12.8 — — 16.5 — — Cash and cash equivalents 2.8 — — 2.7 — — Investments measured at net asset value (a) 93.4 — — 82.2 — — Total plan assets $ 993.2 $ 899.8 $ — $ 946.9 $ 864.7 $ — (a) In accordance with ASC Topic 820-10, certain investments were measured at net asset value per share (“NAV”). In cases where the fair value was measured at NAV using the practical expedient provided for in ASC Topic 820-10, the investments have not been classified in the fair value hierarchy. The fair value amounts presented in these tables are intended to permit reconciliation of the fair value hierarchy to the tables above.
Expected future benefit payments and related federal subsidy receipts	2021 2022 2023 2024 2025 2025- 2029 Pension benefits $ 25.2 $ 26.3 $ 27.3 $ 28.5 $ 29.8 $ 168.9 Other benefits 2.9 3.2 3.5 3.6 3.6 18.3 Subsidy receipts 0.1 0.1 0.1 0.2 0.2 1.0
Pension Benefits
Defined Benefit Plan Disclosure
Schedule of net benefit costs and assumptions used in calculation	The following tables provide the components of net periodic benefit cost for the pension plans including amounts recognized in OCI. For the years ended September 30, 2020, 2019 and 2018, service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit cost were reported in “Other income, net” in the Consolidated Statements of Operations. North America Year Ended September 30, 2020 2019 2018 Components of net periodic benefit cost Service cost $ 4.3 $ 3.7 $ 4.2 Interest cost 3.7 4.1 3.6 Expected return on plan assets (6.4) (6.4) (4.4) Recognized net actuarial loss 1.8 — 1.1 Recognized prior service cost 0.1 0.1 0.1 Net periodic benefit cost $ 3.5 $ 1.5 $ 4.6 Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans 3.32 % 4.30 % 3.86 % Discount rate — Canadian plans 2.84 % 3.53 % 3.63 % Rate of compensation increase — U.S. plans 3.00 % 3.00 % 3.00 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.69 % Expected return on plan assets — U.S. plans 5.53 % 5.74 % 5.46 % Expected return on plan assets — Canadian plans 5.75 % 5.75 % 6.00 % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income Net loss (gain) $ 6.6 $ 13.9 $ (3.7) Recognized loss (1.8) — (1.1) Recognized prior service cost (0.1) (0.1) (0.1) Total recognized in other comprehensive income (before tax effects) $ 4.7 $ 13.8 $ (4.9) Other International Year Ended September 30, 2020 2019 2018 Components of net periodic benefit cost Service cost $ — $ 5.6 $ 6.7 Interest cost 14.7 18.9 19.6 Expected return on plan assets (24.6) (28.8) (31.7) Recognized curtailment (a) — 1.5 — Net periodic benefit income $ (9.9) $ (2.8) $ (5.4) Weighted-average assumptions used to determine net benefit cost Discount rate 1.84 % 2.81 % 2.72 % Rate of compensation increase 2.55 % 2.75 % 2.70 % Expected return on plan assets 2.53 % 3.51 % 3.56 % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income Net loss (gain) $ 14.2 $ (14.4) $ 8.2 Prior service cost (b) 11.4 1.5 — Recognized curtailment (a) — (1.5) — Total recognized in other comprehensive income (before tax effects) $ 25.6 $ (14.4) $ 8.2 (a) In September 2019, the Company signed an amendment to the pension deed to close the defined benefit plan for Weetabix employees in the U.K. participating in the group scheme. Eligibility is frozen to new entrants, and the benefit accrual is frozen with respect to current participants. Due to the closure of the group scheme plan, the prior service cost recognized in accumulated OCI in connection with the GMP high court rulings was reclassified to earnings during the year ended September 30, 2019. (b) During the year ended September 30, 2020, the Company recognized prior service cost as a result of an amendment to the benefit plan for Weetabix employees in the U.K. participating in the group scheme. During the year ended September 30, 2019, the Company recognized prior service cost as a result of U.K. high court rulings made in connection with the GMP.
Other Benefits
Defined Benefit Plan Disclosure
Schedule of net benefit costs and assumptions used in calculation	The following table provides the components of net periodic benefit cost for the other postretirement benefit plans including amounts recognized in OCI. For the years ended September 30, 2020, 2019 and 2018, service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit cost were reported in “Other income, net” in the Consolidated Statements of Operations. Year Ended September 30, 2020 2019 2018 Components of net periodic benefit cost Service cost $ 0.6 $ 0.4 $ 0.5 Interest cost 1.9 2.1 2.1 Recognized net actuarial loss 0.6 — 0.3 Recognized prior service credit (4.7) (4.7) (4.7) Net periodic benefit cost $ (1.6) $ (2.2) $ (1.8) Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans 3.20 % 4.27 % 3.77 % Discount rate — Canadian plans 2.86 % 3.54 % 3.69 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Changes in benefit obligation recognized in Total Comprehensive Income Net loss (gain) $ 4.6 $ 11.5 $ (9.9) Recognized net actuarial loss (0.6) — (0.3) Recognized prior service credit 4.7 4.7 4.7 Currency translation — — 0.4 Total recognized in other comprehensive income (before tax effects) $ 8.7 $ 16.2 $ (5.1)

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Sep. 30, 2020
Post Stock Settled
Share-based Payment Award [Line Items]
Stock Appreciation Rights, Activity	in millions, except Post SSARs or where otherwise indicated Post SSARs Weighted- Weighted- Aggregate Outstanding at September 30, 2019 136,031 $ 41.94 Granted — — Exercised (1,031) 18.10 Forfeited — — Expired — — Outstanding at September 30, 2020 135,000 42.12 2.75 $ 5.9 Vested and expected to vest as of September 30, 2020 135,000 42.12 2.75 5.9 Exercisable at September 30, 2020 135,000 42.12 2.75 5.9
Restricted Stock Units, Activity	in millions, except Post RSUs or where otherwise indicated Post RSUs Weighted- Nonvested at September 30, 2019 1,013,939 $ 81.27 Granted 351,786 103.97 Vested (413,820) 82.16 Forfeited (21,972) 95.08 Nonvested at September 30, 2020 929,933 89.14
Post Cash Settled
Share-based Payment Award [Line Items]
Stock Appreciation Rights, Activity	in millions, except Post SARs or where otherwise indicated Post SARs Weighted- Weighted- Aggregate Outstanding at September 30, 2019 2,500 $ 18.10 Granted — — Exercised (2,500) 18.10 Forfeited — — Expired — — Outstanding at September 30, 2020 — n/a n/a n/a Vested and expected to vest as of September 30, 2020 — n/a n/a n/a Exercisable at September 30, 2020 — n/a n/a n/a
Post Non-Stock Options, Valuation Assumptions	2019 2018 Expected term (in years) 0 0.0 Expected stock price volatility 24.8% 21.5% Risk-free interest rate 1.8% 2.6% Expected dividends 0% 0% Fair value (per Post SAR) $87.84 $79.94
Restricted Stock Units, Activity	in millions, except Post Cash RSUs or where otherwise indicated Post Cash RSUs Weighted- Nonvested at September 30, 2019 49,000 $ 51.43 Granted — — Vested (9,800) 51.43 Forfeited — — Nonvested at September 30, 2020 39,200 51.43
Post Stock Options
Share-based Payment Award [Line Items]
Stock Options, Activity	in millions, except Post stock options or where otherwise indicated Post Stock Options Weighted- Weighted- Aggregate Outstanding at September 30, 2019 1,758,026 $ 58.03 Granted 30,504 106.51 Exercised (89,250) 44.11 Forfeited — — Expired — — Outstanding at September 30, 2020 1,699,280 59.63 5.21 $ 46.1 Vested and expected to vest as of September 30, 2020 1,699,280 59.63 5.21 46.1 Exercisable at September 30, 2020 1,509,246 55.91 4.88 45.6
Stock Options, Valuation Assumptions	2020 2019 2018 Expected term (in years) 6.5 6.5 6.5 Expected stock price volatility 29.2% 29.7% 30.7% Risk-free interest rate 1.8% 3.1% 2.2% Expected dividends 0% 0% 0% Fair value (per Post stock option) $35.32 $33.82 $28.52
Performance-Based Restricted Stock Units
Share-based Payment Award [Line Items]
Performance-Based Restricted Stock Units	in millions, except Post PRSUs or where otherwise indicated Post PRSUs Weighted- Nonvested at September 30, 2019 82,871 $ 112.75 Granted 90,836 138.10 Vested — — Forfeited — — Nonvested at September 30, 2020 173,707 126.00
Post Non-Stock Options, Valuation Assumptions	2020 2019 2018 Expected term (in years) 3.0 3.0 3.0 Expected stock price volatility 22.2% 24.2% 31.8% Risk-free interest rate 1.6% 2.9% 1.8% Fair value (per Post PRSU) $138.10 $122.34 $97.74
BRBR Stock Options
Share-based Payment Award [Line Items]
Stock Options, Activity	in millions, except BellRing stock options or where otherwise indicated BellRing Stock Options Weighted- Weighted- Aggregate Outstanding at September 30, 2019 — $ — Granted 96,000 19.31 Exercised — — Forfeited — — Expired — — Outstanding at September 30, 2020 96,000 19.31 9.15 $ 0.1 Vested and expected to vest as of September 30, 2020 96,000 19.31 9.15 0.1 Exercisable at September 30, 2020 — n/a n/a n/a
Stock Options, Valuation Assumptions	2020 Expected term (in years) 6.5 Expected stock price volatility 38.5% Risk-free interest rate 1.6% Expected dividends 0% Fair value (per BellRing option) $7.92
BRBR Stock Settled
Share-based Payment Award [Line Items]
Restricted Stock Units, Activity	in millions, except BellRing RSUs or where otherwise indicated BellRing RSUs Weighted- Nonvested at September 30, 2019 — $ — Granted 395,232 19.39 Vested — — Forfeited (10,000) 19.31 Nonvested at September 30, 2020 385,232 19.39

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Sep. 30, 2020
Stockholders' Equity Attributable to Parent [Abstract]
Repurchases of Common Stock	September 30, 2020 2019 2018 Shares repurchased 6.1 3.3 2.8 Average share price $ 97.67 $ 98.78 $ 76.21 Total cost including broker’s commissions (a) $ 587.8 $ 330.8 $ 218.7 (a) Of the $587.8 total cost recorded during the year ended September 30, 2020, $7.4 was not settled until October 2020 and was included in “Other current liabilities” on the Consolidated Balance Sheet at September 30, 2020. Of the $330.8 total cost recorded during the year ended September 30, 2019, $8.7 was not settled until October 2019 and was included in “Other current liabilities” on the Consolidated Balance Sheet at September 30, 2019.

Segments (Tables)

Segments (Tables)	12 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Year Ended September 30, 2020 2019 2018 Net Sales Post Consumer Brands $ 1,949.1 $ 1,875.9 $ 1,831.7 Weetabix 440.4 418.2 423.4 Foodservice 1,361.8 1,627.4 1,548.2 Refrigerated Retail 961.2 907.3 790.9 BellRing Brands 988.3 854.4 827.5 Private Brands — — 848.9 Eliminations (2.1) (2.1) (13.4) Total $ 5,698.7 $ 5,681.1 $ 6,257.2 Segment Profit Post Consumer Brands $ 393.5 $ 337.1 $ 329.2 Weetabix 112.3 94.8 87.2 Foodservice 25.6 198.4 157.6 Refrigerated Retail 125.6 95.1 90.0 BellRing Brands 164.0 175.1 124.4 Private Brands — — 60.8 Total segment profit 821.0 900.5 849.2 General corporate expenses and other 109.0 169.6 136.8 Gain on sale of business — (126.6) — Impairment of goodwill and other intangibles — 63.3 124.9 Interest expense, net 388.6 322.4 387.3 Loss on extinguishment of debt, net 72.9 6.1 31.1 Expense (income) on swaps, net 187.1 306.6 (95.6) Earnings before income taxes and equity method loss $ 63.4 $ 159.1 $ 264.7 Net sales by product Cereal and granola $ 2,388.7 $ 2,293.3 $ 2,351.2 Eggs and egg products 1,307.8 1,578.4 1,542.8 Side dishes (including potato products) 536.6 519.6 398.2 Cheese and dairy 253.2 234.6 248.6 Sausage 168.1 149.6 96.0 Protein-based products and supplements 988.7 854.7 827.5 Nut butters and dried fruit and nut — — 487.5 Pasta — — 258.4 Other 57.3 52.5 53.0 Eliminations (1.7) (1.6) (6.0) Total $ 5,698.7 $ 5,681.1 $ 6,257.2 Additions to property and intangibles Post Consumer Brands $ 67.4 $ 62.1 $ 51.5 Weetabix 24.6 37.7 26.3 Foodservice and Refrigerated Retail 139.5 162.3 114.6 BellRing Brands 2.1 3.2 5.0 Private Brands — — 26.6 Corporate 1.0 8.6 1.0 Total $ 234.6 $ 273.9 $ 225.0 Depreciation and amortization Post Consumer Brands $ 112.4 $ 117.4 $ 122.0 Weetabix 35.9 35.0 38.1 Foodservice 119.6 111.8 105.4 Refrigerated Retail 73.1 74.1 57.9 BellRing Brands 25.3 25.3 25.9 Private Brands — — 40.9 Total segment depreciation and amortization 366.3 363.6 390.2 Corporate and accelerated depreciation 4.0 16.0 8.2 Total $ 370.3 $ 379.6 $ 398.4 September 30, 2020 2019 2018 Assets, end of year Post Consumer Brands $ 3,291.7 $ 3,296.3 $ 3,391.7 Weetabix 1,864.5 1,779.1 1,853.3 Foodservice and Refrigerated Retail 5,022.0 5,033.8 5,132.4 BellRing Brands 653.5 594.0 559.3 Private Brands — — 1,055.3 Corporate 1,315.0 1,248.4 1,065.5 Total $ 12,146.7 $ 11,951.6 $ 13,057.5

Summary Quarterly Financial Inf

Summary Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Sep. 30, 2020
Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information	First Second Third Fourth Quarter Quarter Quarter Quarter Fiscal 2020 Net sales $ 1,456.8 $ 1,494.2 $ 1,336.4 $ 1,411.3 Gross profit 471.5 438.8 436.8 440.3 Net earnings (loss) 99.2 (191.4) 36.0 57.0 Net earnings (loss) available to common shareholders 99.2 (191.4) 36.0 57.0 Basic earnings (loss) per share $ 1.40 $ (2.76) $ 0.53 $ 0.85 Diluted earnings (loss) per share $ 1.38 $ (2.76) $ 0.52 $ 0.83 Fiscal 2019 Net sales $ 1,411.3 $ 1,387.8 $ 1,439.2 $ 1,442.8 Gross profit 426.5 451.3 462.1 452.2 (Gain) loss on sale of business (124.7) (2.6) — 0.7 Impairment of goodwill and other intangible assets — — — 63.3 Net earnings (loss) 125.6 44.0 16.2 (61.1) Net earnings (loss) available to common shareholders 123.6 43.0 16.2 (61.1) Basic earnings (loss) per share $ 1.85 $ 0.61 $ 0.22 $ (0.84) Diluted earnings (loss) per share $ 1.67 $ 0.58 $ 0.21 $ (0.84)

Background (Details)

Background (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Oct. 21, 2019	Oct. 01, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Schedule of Equity Method Investments [Line Items]
Proceeds from initial public offering			$ 524.4	$ 0	$ 0
BellRing Brands, Inc. | Common Class A
Schedule of Equity Method Investments [Line Items]
Common Stock, Shares, Issued	39.4
Par value of common stock	$ 0.01
Offering Price Per Share of Initial Public Offering	$ 14
Proceeds from initial public offering	$ 524.4
BellRing Brands, Inc. | Common Class B
Schedule of Equity Method Investments [Line Items]
Par value of common stock	$ 0.01
Common Stock, Voting Rights	67.00%
Post
Schedule of Equity Method Investments [Line Items]
Third Party Costs			$ 2.5	6.7
8th Avenue
Schedule of Equity Method Investments [Line Items]
Business Divestiture, Purchase Price Adjustment, Net Working Capital Settlement				$ 16.8
Equity Method Investment, Ownership Percentage		60.50%	60.50%	60.50%
Third Party Costs				$ 9.9	$ 12.4
BellRing Brands, LLC | BellRing Brands, Inc.
Schedule of Equity Method Investments [Line Items]
BellRing Brands, Inc ownership of BellRing Brands, LLC	28.80%
BellRing Brands, LLC | Post
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	71.20%
BellRing Brands, LLC | Post | Minimum
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	50.00%
Post | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Proceeds from independent capitalization of a subsidiary		$ 875

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Weetabix Segment | Operating Segments
Business Acquisition
Receivables Sold	$ 125	$ 120.7

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 2,979.2	$ 2,736.9
Accumulated depreciation	(1,199.5)	(1,000.9)
Property, net	1,779.7	1,736
Depreciation	209.6	218.3	$ 221
Land
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	93.1	91.1
Building and leasehold improvements
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 880.5	796.7
Building and leasehold improvements | Minimum
Property, Plant and Equipment, Net [Abstract]
Useful life	1 year
Building and leasehold improvements | Maximum
Property, Plant and Equipment, Net [Abstract]
Useful life	38 years
Machinery and equipment
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 1,766.8	1,595.8
Machinery and equipment | Minimum
Property, Plant and Equipment, Net [Abstract]
Useful life	1 year
Machinery and equipment | Maximum
Property, Plant and Equipment, Net [Abstract]
Useful life	29 years
Software
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 111.4	106
Software | Minimum
Property, Plant and Equipment, Net [Abstract]
Useful life	1 year
Software | Maximum
Property, Plant and Equipment, Net [Abstract]
Useful life	7 years
Construction in Progress
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 127.4	$ 147.3

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived and Indefinite-Lived, Intangible Assets
Amortization of intangible assets	$ 160.3	$ 161.3	$ 177.4
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2019	160.4
2020	160.4
2021	160.2
2022	159
2023	157.7
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	3,102.9	3,094
Finite-Lived Intangible Assets, Accumulated Amortization	(951.9)	(790.5)
Finite-Lived Intangible Assets, Net	2,151	2,303.5
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Carrying amount, total	4,149.4	4,129
Other intangible assets, net	3,197.5	3,338.5
Customer Relationships
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	2,304.8	2,297.2
Finite-Lived Intangible Assets, Accumulated Amortization	(681.9)	(562.2)
Finite-Lived Intangible Assets, Net	1,622.9	1,735
Trademarks
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	795	793.7
Finite-Lived Intangible Assets, Accumulated Amortization	(266.9)	(225.2)
Finite-Lived Intangible Assets, Net	528.1	568.5
Other Intangible Assets
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	3.1	3.1
Finite-Lived Intangible Assets, Accumulated Amortization	(3.1)	(3.1)
Finite-Lived Intangible Assets, Net	0	0
Trademarks
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Indefinite-lived Intangible Assets (Excluding Goodwill)	$ 1,046.5	$ 1,035

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Recoverability of Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2020
Trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets (Excluding Goodwill)	$ 1,035		$ 1,046.5
Weetabix Brand | Trademarks
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)		$ 124.9
Indefinite-lived Intangible Assets (Excluding Goodwill)		$ 261.8
Trademarks | All Whites
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)	14.6
Finite-Lived Trademarks, Gross	$ 0

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Sales	$ 1,411.3	$ 1,336.4	$ 1,494.2	$ 1,456.8	$ 1,442.8	$ 1,439.2	$ 1,387.8	$ 1,411.3	$ 5,698.7	$ 5,681.1	$ 6,257.2
Cost of goods sold									3,911.3	3,889	4,403.2
Gross Profit	$ 440.3	$ 436.8	$ 438.8	$ 471.5	452.2	462.1	451.3	426.5	1,787.4	1,792.1	1,854
Selling, general and administrative expenses									934.3	911.6	976.4
Amortization of intangible assets									160.3	161.3	177.4
Gain on sale of business					0.7	0	(2.6)	(124.7)	0	(126.6)	0
Impairment of goodwill and other intangible assets					$ 63.3	$ 0	$ 0	$ 0	0	63.3	124.9
Other operating (income) expenses, net									(7.7)	1.5	1.8
Operating Profit									$ 700.5	781	$ 573.5
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Sales										(24.9)
Cost of goods sold										0
Gross Profit										(24.9)
Selling, general and administrative expenses										(26.1)
Amortization of intangible assets										0
Gain on sale of business										0
Impairment of goodwill and other intangible assets										0
Other operating (income) expenses, net										0
Operating Profit										1.2
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Sales										5,681.1
Cost of goods sold										3,889
Gross Profit										1,792.1
Selling, general and administrative expenses										911.6
Amortization of intangible assets										161.3
Gain on sale of business										(126.6)
Impairment of goodwill and other intangible assets										63.3
Other operating (income) expenses, net										1.5
Operating Profit										781
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net Sales										5,706
Cost of goods sold										3,889
Gross Profit										1,817
Selling, general and administrative expenses										937.7
Amortization of intangible assets										161.3
Gain on sale of business										(126.6)
Impairment of goodwill and other intangible assets										63.3
Other operating (income) expenses, net										1.5
Operating Profit										$ 779.8

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Cost of Products Sold (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Cost Of Goods Sold, Storage And Warehouse Costs	$ 177.8	$ 170.1	$ 169.4

Summary of Significant Accou_10

Summary of Significant Accounting Policies Advertising (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Accounting Policies [Abstract]
Prepaid Advertising	$ 1.3	$ 3.9

Recently Issued and Adopted A_2

Recently Issued and Adopted Accounting Standards (Details) - USD ($) $ in Millions	Oct. 01, 2019	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncement, Early Adoption
Adoption of accounting standards updates		$ (0.9)	$ 1.4
Right-of-use assets | Accounting Standards Update 2016-02
New Accounting Pronouncement, Early Adoption
Adoption of accounting standards updates	$ 158.1
Lease liabilities | Accounting Standards Update 2016-02
New Accounting Pronouncement, Early Adoption
Adoption of accounting standards updates	$ 168.2

Business Combinations (Details)

Business Combinations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Jul. 01, 2020	Jan. 12, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition
Business Combination, Acquisition Related Costs			$ 3.8	$ 8.9	$ 23.4
Payments to Acquire Businesses, Net of Cash Acquired			19.9	0	1,454.4
Goodwill			4,438.6	4,399.8
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred				0
Accrued legal settlements, current			13.2	$ 16.1
Pro forma net sales					6,423.8
Pro forma net earnings available to common stockholders					$ 486.4
Pro forma basic earnings per share					$ 7.30
Pro forma diluted earnings per share					$ 6.54
Henningsen Foods
Business Acquisition
Cash and cash equivalents			2.8
Total acquisition cost			32.6
Payments to Acquire Businesses, Gross	$ 22.7
Business Combination, Bargain Purchase, Gain Recognized, Amount			11.7
Business Combination, Working Capital Receivable			$ 1.8
Payments to Acquire Businesses, Base Purchase Price	$ 20
Bob Evans Farms
Business Acquisition
Business Acquisition, Share Price		$ 77
Shares for which merger consideration has been paid				2,500
Payments to Acquire Businesses, Net of Cash Acquired		$ 1,381.2
Payments to be made subsequent to the closing of the acquisition		$ 342.4
Shares not yet paid		4,350
Payments to appraisal rights holders, including interest				$ 257.6
Business Acquisition, Goodwill, Expected Tax Deductible Amount		$ 13.8
Cash and cash equivalents				15.6	$ 15.6
Receivables				58.5	58.5
Inventories				27.1	27.1
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory				0
Prepaid expenses and other current assets				34.3	34.3
Property				184.3	184.3
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment				0
Goodwill				897.6	898.3
Goodwill, Purchase Accounting Adjustments				(0.7)
Other intangible assets				782	782
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles				0
Other assets				0.4	0.4
Accounts payable				(18.2)	(18.2)
Other current liabilities				(58.5)	(58.5)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities				194.2	194.9
Other Liabilities				(5.3)	(5.3)
Total acquisition cost				1,723.6	1,723.6
Bob Evans Farms | Customer Relationships
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		$ 376
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		18 years
Bob Evans Farms | Trademarks
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		$ 6
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Bob Evans Farms | Interest expense, net
Business Acquisition
Litigation Settlement, Expense					$ 13.4
Bob Evans Farms | SG&A and Interest expense, net
Business Acquisition
Litigation Settlement, Expense				9.7
Bob Evans Farms | Trademarks
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets		$ 400
Cash and Cash Equivalents | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets				0
Accounts Receivable | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets				0
Prepaid expenses and other current assets | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets				0
Other Assets | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets				0
Accounts Payable | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities				0
Other current liabilities | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities				0
Accrued legal settlements, current				19.1
Deferred tax liability - long-term | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities				0.7
Other liabilities | Bob Evans Farms
Business Acquisition
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities				$ 0

Restructuring (Details)

Restructuring (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Restructuring Reserve [Roll Forward]
Balance	$ 0.1	$ 2.7	$ 0
Charge to expense		9.6	5.2
Cash payments	(0.1)	(4.8)
Non-cash charges		(7.4)	(2.5)
Balance	0	0.1	2.7
Total expected restructuring charge	14.8
Cumulative incurred to date	14.8
Remaining expected restructuring charge	0
Employee Severance
Restructuring Reserve [Roll Forward]
Balance	0.1	2.7	0
Charge to expense		2.2	2.7
Cash payments	(0.1)	(4.8)
Non-cash charges		0	0
Balance	0	0.1	2.7
Total expected restructuring charge	4.9
Cumulative incurred to date	4.9
Remaining expected restructuring charge	0
Accelerated depreciation
Restructuring Reserve [Roll Forward]
Balance	0	0	0
Charge to expense		7.4	2.5
Cash payments	0	0
Non-cash charges		(7.4)	(2.5)
Balance	0	$ 0	$ 0
Total expected restructuring charge	9.9
Cumulative incurred to date	9.9
Remaining expected restructuring charge	$ 0

Divestitures and Amounts Held_2

Divestitures and Amounts Held For Sale (Details) - USD ($) shares in Millions	Oct. 01, 2018	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Foreign currency losses reclassified from accumulated OCI						$ 0	$ 42,100,000	$ 0
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
(Gain) loss on sale of business		$ 700,000	$ 0	$ (2,600,000)	$ (124,700,000)	0	(126,600,000)	0
Impairment of Long-Lived Assets to be Disposed of						2,700,000	(124,600,000)
8th Avenue | Other liabilities held for sale | Loss on extinguishment of debt, net
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Loss (gain) on assets held for sale							2,600,000
Post Consumer Brands Segment | Clinton, Massachusetts facility
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Property, net		8,400,000				3,400,000	8,400,000
Impairment of Long-Lived Assets to be Disposed of						2,600,000
Loss (gain) on assets held for sale							(600,000)
Post Consumer Brands Segment | Asheboro, North Carolina facility
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Property, net		$ 1,500,000				1,400,000	1,500,000
Impairment of Long-Lived Assets to be Disposed of						100,000
Weetabix Segment | Corby, United Kingdom facility
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Property, net						$ 2,500,000
8th Avenue
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Divestiture, Purchase Price Adjustment, Net Working Capital Settlement							16,800,000
Foreign currency losses reclassified from accumulated OCI							$ 42,100,000
Equity Method Investment, Ownership Percentage	60.50%	60.50%				60.50%	60.50%
Third Party Costs							$ 9,900,000	12,400,000
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
(Gain) loss on sale of business							$ (126,600,000)
Post | 8th Avenue
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from independent capitalization of a subsidiary	$ 875,000,000
Preferred Stock, Value, Subscriptions	250,000,000
THL | 8th Avenue
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Preferred Stock, Liquidation Preference, Value	$ 100
Preferred Stock, Shares Issued	2.5
Preferred Stock, Dividend Rate, Agreed upon Percentage	11.00%
Equity Method Investment, Ownership Percentage	39.50%
2018 Bridge Loan | Post | 8th Avenue
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from issuance of unsecured debt								$ 625,000,000

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Goodwill [Line Items]
Goodwill	$ 4,438.6	$ 4,399.8
Operating Segments
Goodwill [Line Items]
Goodwill (gross)	5,211.2	5,172.4	$ 5,223.5
Accumulated impairment losses	(772.6)	(772.6)	(723.9)
Goodwill	4,438.6	4,399.8	4,499.6
Impairment Loss		48.7
Acquisition related adjustment		(0.7)
Currency translation adjustment	$ 38.8	(50.4)
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	13.00%
Operating Segments | Post Consumer Brands Segment
Goodwill [Line Items]
Goodwill (gross)	$ 2,011.8	2,011.8	2,012
Accumulated impairment losses	(609.1)	(609.1)	(609.1)
Goodwill	1,402.7	1,402.7	1,402.9
Acquisition related adjustment		0
Currency translation adjustment	0	(0.2)
Operating Segments | Weetabix Segment
Goodwill [Line Items]
Goodwill (gross)	889.5	850.7	900.9
Accumulated impairment losses	0	0	0
Goodwill	889.5	850.7	900.9
Acquisition related adjustment		0
Currency translation adjustment	38.8	(50.2)
Operating Segments | Foodservice Segment
Goodwill [Line Items]
Goodwill (gross)	1,335.6	1,335.6	1,336.1
Accumulated impairment losses	0	0	0
Goodwill	1,335.6	1,335.6	1,336.1
Acquisition related adjustment		(0.5)
Currency translation adjustment	$ 0	0
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	4.00%
Operating Segments | Refrigerated Retail Segment
Goodwill [Line Items]
Goodwill (gross)	$ 793.6	793.6	793.8
Accumulated impairment losses	(48.7)	(48.7)	0
Goodwill	744.9	744.9	793.8
Impairment Loss		48.7
Acquisition related adjustment		(0.2)
Currency translation adjustment	0	0
Operating Segments | BellRing Brands
Goodwill [Line Items]
Goodwill (gross)	180.7	180.7	180.7
Accumulated impairment losses	(114.8)	(114.8)	(114.8)
Goodwill	65.9	65.9	$ 65.9
Acquisition related adjustment		0
Currency translation adjustment	$ 0	$ 0

Noncontrolling Interests, Equ_3

Noncontrolling Interests, Equity Interests and Related Party Transactions (Details) $ in Millions	12 Months Ended
	Sep. 30, 2020USD ($)joint_venture	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Oct. 21, 2019	Oct. 01, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Equity method (loss) earnings, net of tax	$ (30.9)	$ (37)	$ (0.3)
Related party	3.2	5.1
Equity method investments	114.1	145.5
Increase in additional paid-in capital related to net proceeds from IPO	524.4	0	0
Net transfers from noncontrolling interest	390.6
Additional Paid-in Capital
Schedule of Equity Method Investments [Line Items]
Net transfers from noncontrolling interest	455.6
8th Avenue
Schedule of Equity Method Investments [Line Items]
Net Loss Available to 8th Avenue Common Shareholders	$ (38.9)	$ (46.7)
Equity Method Investment, Ownership Percentage	60.50%	60.50%			60.50%
Equity method loss available to Common Shareholders	$ (23.5)	$ (28.3)
Amortization of basis difference, net of tax	6.9	8.8
Equity method (loss) earnings, net of tax	(30.4)	(37.1)
Total Basis Difference Recognized					$ 70.3
Remaining Basis Difference to be Amortized	54.6	61.5
Net sales	924.2	838.5
Gross profit	160	139.6
Net loss	(6.4)	(17.6)
Less: Preferred stock dividend	32.5	29.1
Current assets	251.5	209.2
Other assets	830.1	826.2
Total Assets	1,081.6	1,035.4
Current portion of long-term debt	5.2	5.2
Accounts payable and other current liabilities	113.3	74.4
Long-term debt	663.3	644.9
Other liabilities	71.6	76.5
Total Liabilities	853.4	801
Preferred stock	61.6	29.1
Other shareholders’ equity	166.6	205.3
Shareholders’ Equity	228.2	234.4
Total Liabilities and Shareholders’ Equity	1,081.6	1,035.4
Revenue from Related Parties	5.7	4.7
Purchases from and Royalties paid to Related Party	$ 9.9	9.4
Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity method (loss) earnings, net of tax	$ (0.5)	0.1	$ (0.3)
Weetabix East Africa Limited | Post
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	50.10%
Weetabix Group
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures Acquired | joint_venture	2
Inventories | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Amortization of basis difference, net of tax		2
Other Assets | Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 4	5
Notes Receivable, Related Parties, Noncurrent	0.5	0.5
Other Liabilities | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Due to Related Parties, Noncurrent	0.7	0.7
Equity Method Investments | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Equity method investments	110.1	140.5
Accounts Receivable | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Related party	3.2	5.1
Accounts Payable | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Accounts Payable, Related Parties	0.6	0.6
Selling, general and administrative expenses
Schedule of Equity Method Investments [Line Items]
MSA and Advisory Income	3.9	$ 4.1
BellRing | Additional Paid-in Capital
Schedule of Equity Method Investments [Line Items]
Increase in additional paid-in capital related to net proceeds from IPO	524.4
Increase in additional paid-in capital related to establishment of noncontrolling interest	65
Decrease in additional paid-in capital related to tax effects of IPO	(133.8)
Net transfers from noncontrolling interest	$ 455.6
Post | BellRing Brands, LLC
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent				71.20%
Post | BellRing Brands, LLC | Minimum
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent				50.00%
BellRing Brands, Inc. | Common Class B
Schedule of Equity Method Investments [Line Items]
Common Stock, Voting Rights				67.00%
BellRing Brands, Inc. | BellRing Brands, LLC
Schedule of Equity Method Investments [Line Items]
BellRing Brands, Inc ownership of BellRing Brands, LLC				28.80%

Income Taxes (Loss) Earnings be

Income Taxes (Loss) Earnings before Income Taxes and Equity Method Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Earnings before Income Taxes and Equity Method Loss [Abstract]
Domestic	$ (36.4)	$ 80.4	$ 289
Foreign	99.8	78.7	(24.3)
Earnings before Income Taxes and Equity Method Loss	63.4	159.1	264.7
Income tax expense (benefit)	$ 3.5	$ (3.9)	$ (204)
Effective Income Tax Rate Reconciliation, Percent	5.50%	(2.50%)	(77.10%)

Income Taxes - Income tax (bene

Income Taxes - Income tax (benefit) expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Current
Federal	$ 31.3	$ 61.5	$ 27.3
State	7.1	2.6	5.2
Foreign	8.7	12.3	20
Current	47.1	76.4	52.5
Deferred
Federal	(45.6)	(61.8)	(253.5)
State	(14.5)	(15.2)	21.4
Foreign	16.5	(3.3)	(24.4)
Deferred	(43.6)	(80.3)	(256.5)
Income tax expense (benefit)	$ 3.5	$ (3.9)	$ (204)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax (Benefit) (Details) - USD ($) $ in Millions	Dec. 22, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed tax (a)		$ 13.3	$ 33.4	$ 64.9
Enacted tax law changes, including the Tax Act		(1.5)	(4.8)	(270.9)
Non-deductible goodwill impairment loss		0	6.9	0
Non-deductible compensation		4.5	2.7	1.2
Transaction costs		(1.1)	2.2	1.5
Domestic production activities deduction		0	0	(5.9)
State income tax (benefit) expense, net of effect on federal tax		(4.3)	(0.7)	5.6
Non-taxable interest income		0	0	(2.4)
Valuation allowances		5	6.6	4.1
Change in deferred tax rates		11.1	(4.6)	0.3
Uncertain tax positions		1.2	(7.9)	0.3
Net losses and basis difference attributable to equity method investment		(6.5)	4.4	0
Income tax credits		(2.6)	(3)	(2.3)
Rate differential on foreign income		(10.8)	(7.7)	(5.3)
Excess tax benefits for share-based payments		(1.4)	(33.4)	(1.8)
Gain on bargain purchase		(2.5)	0	0
Enhanced deduction for food donation		(1.5)	(0.6)	(0.8)
Return-to-provision		(1.5)	0.6	(1)
Other, net (none in excess of 5% of statutory tax)		2.1	2	8.5
Income tax expense (benefit)		$ 3.5	$ (3.9)	$ (204)
Fiscal 2018 Blended Tax Rate				24.50%
Income Tax Reconciliation Threshold for Other Expenses		5.00%	5.00%	5.00%
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal Income Tax Rate	35.00%
UNITED STATES
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Fiscal 2018 Blended Tax Rate				24.50%
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal Income Tax Rate		21.00%	21.00%

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - Noncurrent - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Assets
Components of Deferred Tax Assets [Abstract]
Derivative mark-to-market adjustments	$ 133.8	$ 98.5
Disallowed Interest Carryforwards	36	29.7
Net operating loss and credit carryforwards	33.7	30.8
Lease liabilities	26.2	0
Stock-based and deferred compensation	18.4	19.9
Accrued vacation, incentive and severance	8.3	7.7
Accrued liabilities	9	15.6
Inventory	3.2	6.2
Other items	4.6	4.5
Deferred Tax Assets, Gross, Total	273.2	212.9
Valuation allowance	(41.1)	(32.6)
Total deferred taxes	232.1	180.3
Liability
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(619.9)	(652.4)
Property	(192.3)	(173.4)
Investment in partnership (a)	(144.6)	0
ROU assets	(25.5)	0
Basis difference attributable to equity method investment	(22.5)	(30)
Pension and other postretirement benefits	(10.1)	(11.2)
Other items, current liabilities	(1.7)	(1.8)
Deferred Tax Liabilities, Gross	(1,016.6)	(868.8)
Net Assets
Components of Deferred Tax Assets [Abstract]
Derivative mark-to-market adjustments	133.8	98.5
Disallowed Interest Carryforwards	36	29.7
Net operating loss and credit carryforwards	33.7	30.8
Lease liabilities	26.2	0
Stock-based and deferred compensation	18.4	19.9
Accrued vacation, incentive and severance	8.3	7.7
Accrued liabilities	9	15.6
Inventory	3.2	6.2
Other items	2.9	2.7
Valuation allowance	(41.1)	(32.6)
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(619.9)	(652.4)
Property	(192.3)	(173.4)
Investment in partnership (a)	(144.6)	0
ROU assets	(25.5)	0
Basis difference attributable to equity method investment	(22.5)	(30)
Pension and other postretirement benefits	(10.1)	(11.2)
Deferred Tax Liabilities, Gross	(743.4)	(655.9)
Total deferred tax liabilities, gross	$ (784.5)	$ (688.5)

Income Taxes - Income Taxes Nar

Income Taxes - Income Taxes Narrative (Details) - USD ($)	Dec. 22, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosures
Operating Loss Carryforwards, Limitations on Usage		$ 23,400,000
Undistributed Earnings of Foreign Subsidiaries		118,200,000
Newly Enacted Tax Rate				21.00%
Federal Income Tax Rate	35.00%
Fiscal 2018 Blended Tax Rate				24.50%
Tax Benefit Due to Newly Enacted Tax Rate			$ 200,000	$ 281,200,000
Tax (Benefit) Expense Due to One-Time Transition Tax			$ (4,600,000)	$ 10,300,000
Domestic Tax Authority
Income Tax Disclosures
Operating Loss Carryforwards		41,800,000
State and Local Jurisdiction
Income Tax Disclosures
Operating Loss Carryforwards		576,400,000
Foreign Tax Authority
Income Tax Disclosures
Operating Loss Carryforwards		$ 12,700,000
UNITED STATES
Income Tax Disclosures
Federal Income Tax Rate		21.00%	21.00%
Fiscal 2018 Blended Tax Rate				24.50%

Unrecognized tax benefits (Deta

Unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 8.6	$ 9.9	$ 8.6
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	1.7	0.1	2
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	0	5.7	0.1
Unrecognized Tax Benefits, Held for Sale Liabilities	0	0	(0.6)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(0.5)	(7.1)	0
Unrecognized Tax Benefits	9.8	8.6	9.9
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	9.6
Decrease in Unrecognized Tax Benefits is Reasonably Possible	1.8
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	0	(2.5)	$ 0.8
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 1	$ 1

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended									12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share, Diluted
Net Earnings Available to Common Shareholders	$ 57	$ 36	$ (191.4)	$ 99.2	$ (61.1)	$ 16.2	$ 43	$ 123.6		$ 0.8	$ 121.7	$ 457.3
Dilutive impact of BellRing net earnings										0	0	0
Dilutive preferred stock dividends										0	3	10
Net Income (Loss) Available to Common Stockholders, Diluted										$ 0.8	$ 124.7	$ 467.3
Weighted-average shares for basic earnings per share										68.9	70.8	66.6
Effect of dilutive securities										1.2	4.3	9.3
Weighted-average shares for diluted earnings per share										70.1	75.1	75.9
Basic earnings per common share (in usd per share)	$ 0.85	$ 0.53	$ (2.76)	$ 1.40	$ (0.84)	$ 0.22	$ 0.61	$ 1.85		$ 0.01	$ 1.72	$ 6.87
Diluted earnings per common share (in usd per share)	$ 0.83	$ 0.52	$ (2.76)	$ 1.38	$ (0.84)	$ 0.21	$ 0.58	$ 1.67		$ 0.01	$ 1.66	$ 6.16
Stock Options
Earnings Per Share, Diluted
Effect of dilutive securities										0.6	1.6	1.8
Stock Appreciation Rights
Earnings Per Share, Diluted
Effect of dilutive securities										0.1	0.1	0.1
Restricted Stock
Earnings Per Share, Diluted
Effect of dilutive securities										0.4	0.5	0.4
Performance-based Restricted Stock Units
Earnings Per Share, Diluted
Effect of dilutive securities										0.1	0	0
Preferred Stock
Earnings Per Share, Diluted
Effect of dilutive securities										0	2.1	7
Series C Preferred Stock
Earnings Per Share, Diluted
Preferred Stock, Dividend Rate, Percentage							2.50%
Conversion of Stock, Shares Converted							3.2
Series B Preferred Stock
Earnings Per Share, Diluted
Preferred Stock, Dividend Rate, Percentage									3.75%
Conversion of Stock, Shares Converted									1.5
Common Stock
Earnings Per Share, Diluted
Preferred Stock Conversion, Shares Issued							5.9		3.1		5.9	3.1

Earnings per Share Antidilutive

Earnings per Share Antidilutive shares excluded from earnings per share (Details) - shares shares in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.1	0.1	0.6
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0	0.1
Performance-based Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.1	0	0

Supplemental Operations State_3

Supplemental Operations Statement and Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards updates		$ (0.9)	$ 1.4
Advertising and promotion expenses (a)	$ 146	122.3	153.4
Repair and maintenance expenses	140	156.9	149.1
Research and development expenses	28.5	25	25.1
Interest income	(6.3)	(7.9)	(7.4)
Interest paid	348.8	344.4	373.9
Income taxes paid	54.4	65	23
Accrued additions to property	$ 29.8	24.7	$ 30.4
Advertising and Promotion Expenses | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards updates		$ 23.7

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Receivables, net
Trade	$ 395.4	$ 407.8
Income tax receivable	26.6	21.9
Related party	3.2	5.1
Other	19.8	12.3
Gross receivables	445	447.1
Allowance for doubtful accounts	(3.4)	(2)
Receivables, net	441.6	445.1
Inventories
Raw materials and supplies	118.1	99.4
Work in process	17.8	19.4
Finished products	429.4	425.4
Flocks	34.1	35.6
Inventories	599.4	579.8
Other Assets
Pension asset	$ 159	$ 166.7
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating ROU Assets	$ 116.3	$ 0
Equity securities	27.9	0
Other	25.8	38.8
Other Assets	329	205.5
Accounts Payable
Trade	357.6	349.6
Book cash overdrafts	0.7	35.1
Other	9.6	10.9
Accounts payable	367.9	395.6
Current Liabilities
Advertising and promotion	44.9	45.2
Accrued interest	85.9	46
Accrued compensation	98.5	85.3
Hedging liabilities	$ 187.9	$ 87.6
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LiabilitiesCurrentAbstract	us-gaap:LiabilitiesCurrentAbstract
Operating lease liabilities - current	$ 23.6
Accrued legal settlements	13.2	$ 16.1
Accrued appraisal rights and related interest	0	19.1
Other	87.6	94.5
Other current liabilities	541.6	393.8
Other Liabilities
Pension and other postretirement benefit obligations	77.7	66
Hedging liabilities - non-current	355.2	330.5
Accrued compensation - non-current	$ 30.2	$ 34
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LiabilitiesNoncurrentAbstract	us-gaap:LiabilitiesNoncurrentAbstract
Operating lease liabilities - non-current	$ 103	$ 0
Other	33.7	26.4
Other Liabilities	$ 599.8	$ 456.9

Allowance for Doubtful Accoun_3

Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Allowance For Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of year	$ 2	$ 2.3	$ 1.6
Provision charged to expense	3.3	0.1	0.1
Write-offs, less recoveries	(1.9)	(0.4)	(1.2)
Held for sale assets	0	0	(0.5)
Other, Primarily relates to Acquisitions	0	0	2.3
Balance, end of year	$ 3.4	$ 2	$ 2.3

Derivative Financial Instrume_3

Derivative Financial Instruments and Hedging Derivative Financial Instruments and Hedging Narrative (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Reclassification of gains (losses) previously recorded in AOCI	$ 1.8
Reclassifications to net earnings	1.3	$ 8.2	$ (31)	$ (3.6)
Other reclassifications	$ 0.5	0	0	$ 0.5
Accumulated Other Comprehensive Income, Remaining Net Loss to be Amortized		9.4
Portion Designated as Hedging Instruments | Interest rate swaps
Derivative [Line Items]
Derivative, Notional Amount of Terminated Contracts			800
Portion Designated as Hedging Instruments | Currency Swap
Derivative [Line Items]
Derivative, Notional Amount of Terminated Contracts		448.7	214.2
Portion Designated as Hedging Instruments | Interest expense, net | Interest rate swaps
Derivative [Line Items]
Derivative, Cash Received on Hedge			29.8
Not Designated as Hedging Instrument | Interest expense, net | Interest rate swaps
Derivative [Line Items]
Reclassifications to net earnings		7.2
Accumulated OCI | Portion Designated as Hedging Instruments | Currency Swap
Derivative [Line Items]
Derivative, Cash Received on Hedge		$ 50.3	$ 26.2

Derivative Financial Instrume_4

Derivative Financial Instruments and Hedging (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Level 2
Derivatives, Fair Value
Asset Derivatives:	$ 14.7	$ 23.2
Liability Derivatives:	543.1	418.1
Portion Designated as Hedging Instruments | Level 2
Derivatives, Fair Value
Asset Derivatives:	0	20.5
Liability Derivatives:	0	7.8
Commodity contracts | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	5	1.9
Commodity contracts | Level 2 | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0.1	0.1
Commodity contracts | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	1.4	1
Commodity contracts | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	3.9	0.1
Commodity contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	24.7	47.1
Commodity contracts | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Commodity contracts | Portion Designated as Hedging Instruments | Level 2 | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Commodity contracts | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	0
Commodity contracts | Portion Designated as Hedging Instruments | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	0	0
Energy contracts | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	1.8	0.7
Energy contracts | Level 2 | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0.9	0
Energy contracts | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	10.1	1.5
Energy contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	87.1	39.8
Energy contracts | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Energy contracts | Portion Designated as Hedging Instruments | Level 2 | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Energy contracts | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	0
Foreign exchange contracts | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0.1	1.3
Foreign exchange contracts | Level 2 | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0	19.2
Foreign exchange contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	28.9	0
Foreign exchange contracts | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0	1.3
Foreign exchange contracts | Portion Designated as Hedging Instruments | Level 2 | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0	19.2
Currency Swap | Portion Designated as Hedging Instruments
Derivatives, Fair Value
Derivative, Notional Amount	0	448.7
Interest rate swaps | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	6.8	0
Interest rate swaps | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	176.4	85.1
Interest rate swaps | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	351.3	330.4
Interest rate swaps | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	621.7	73.1
Interest rate swaps | Portion Designated as Hedging Instruments
Derivatives, Fair Value
Derivative, Notional Amount	0	200
Interest rate swaps | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Interest rate swaps | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	1.6
Interest rate swaps | Portion Designated as Hedging Instruments | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	0	6.2
Interest rate swap, rate lock swaps | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	1,666	1,531
Interest rate swap, options | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	$ 433.3	$ 0

Derivative Financial Instrume_5

Derivative Financial Instruments and Hedging Loss (Gain) recognized in earnings from derivative instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Loss (Gain) [Line Items]
(Gain) Loss Recognized in OCI	$ (22.5)	$ (40.5)	$ (72.2)
Mark-to-Market Adjustments
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	117.2	293.1	(96.7)
Cash Settlements Paid (Received), Net
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	71.5	(17.5)	(1.2)
Reclass from AOCI
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	8.4	0	0
Interest expense, net | Mark-to-Market Adjustments
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	(0.2)	0	0
Interest expense, net | Cash Settlements Paid (Received), Net
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	1.8	(31)	(2.3)
Interest expense, net | Reclass from AOCI
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	8.4	0	0
Expense (income) on swaps, net | Mark-to-Market Adjustments
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	117.4	293.1	(96.7)
Expense (income) on swaps, net | Cash Settlements Paid (Received), Net
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	69.7	13.5	1.1
Expense (income) on swaps, net | Reclass from AOCI
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	0	0	0
Commodity contracts | Cost of goods sold
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	3.8	2.8	4
Energy contracts | Cost of goods sold
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	21.6	5	(6.4)
Foreign exchange contracts | Selling, general and administrative expenses
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	(0.1)	0	1.5
Interest rate swaps | Expense (income) on swaps, net
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	187.1	306.6	(95.6)
Portion Designated as Hedging Instruments | Foreign exchange contracts | Selling, general and administrative expenses
Derivative Instruments, Loss (Gain) [Line Items]
(Gain) Loss Recognized in OCI	0	0	(0.2)
Losses (Gains) Reclassified to Net Earnings	0	0	(1.3)
Portion Designated as Hedging Instruments | Currency Swap | Expense (income) on swaps, net
Derivative Instruments, Loss (Gain) [Line Items]
(Gain) Loss Recognized in OCI	(32.2)	(54.3)	(27.8)
Losses (Gains) Reclassified to Net Earnings	0	0	0
Portion Designated as Hedging Instruments | Interest rate swaps | Interest expense, net
Derivative Instruments, Loss (Gain) [Line Items]
(Gain) Loss Recognized in OCI	9.7	13.8	(44.2)
Losses (Gains) Reclassified to Net Earnings	8.2	(31)	(2.3)
Not Designated as Hedging Instrument | Interest rate swaps | Interest expense, net
Derivative Instruments, Loss (Gain) [Line Items]
Loss (Gain) Recognized in Statement of Operations	$ 3	$ 0	$ 0

Derivative Financial Instrume_6

Derivative Financial Instruments and Hedging Derivative and Financial Instruments designated as hedges and Pledged Collateral (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Accumulated Other Comprehensive Income, Cumulative Changes in Net Loss from Hedges, Before Tax	$ 90.2	$ 59.5
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Hedges, Effect Net of Tax	67.9	44.5
Hedging Losses to be Reclassified During Next 12 Months	2.3
Cross Currency Swap Settlements and Unrealized Gains Included in AOCI	99.5	36.5
Cross-currency swap cash settlements recognized in accumulated OCI	52.7	31.7	$ 4.8
Collateral Already Posted	5.3	3.7
Cross Currency Swap Settlements and Unrealized Gains Recognized in AOCI	$ 63	$ 31.7	$ 4.8

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Impairment of goodwill and other intangible assets	$ 63.3	$ 0	$ 0	$ 0	$ 0	$ 63.3	$ 124.9
Deferred compensation investment	11.2				12.8	11.2
Derivative Asset	23.2				14.7	23.2
Equity securities	0				27.9	0
Assets, Fair Value Disclosure	34.4				55.4	34.4
Deferred compensation liabilities	31				29.7	31
Derivative Liability	418.1				543.1	418.1
Liabilities, Fair Value Disclosure	449.1				572.8	449.1
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Deferred compensation investment	11.2				12.8	11.2
Derivative Asset	0				0	0
Equity securities	0				27.9	0
Assets, Fair Value Disclosure	11.2				40.7	11.2
Deferred compensation liabilities	0				0	0
Derivative Liability	0				0	0
Liabilities, Fair Value Disclosure	0				0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt, Fair Value Disclosure	7,412				7,277.8	7,412
Deferred compensation investment	0				0	0
Derivative Asset	23.2					23.2
Asset Derivatives:	23.2				14.7	23.2
Equity securities	0				0	0
Assets, Fair Value Disclosure	23.2				14.7	23.2
Deferred compensation liabilities	31				29.7	31
Derivative Liability	418.1					418.1
Liability Derivatives:	418.1				543.1	418.1
Liabilities, Fair Value Disclosure	449.1				572.8	449.1
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of assets held-for-sale	$ 9.9				7.3	9.9	$ 290.9
(Losses) gains related to assets and liabilities held for sale					(2.7)	124.6
Proceeds from Sale of Assets and Liabilities Held for Sale					(2.4)	(276.6)
Investment in 8th Avenue, working capital and other adjustments						(138.9)
Transfers into assets held for sale					$ 2.5	$ 9.9

Leases (Details)

Leases (Details) - USD ($) $ in Millions	Oct. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Lessee, Lease, Description [Line Items]
Adoption of accounting standards updates			$ (0.9)	$ 1.4
Operating ROU Assets		$ 116.3	$ 0
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]		us-gaap:LiabilitiesCurrentAbstract	us-gaap:LiabilitiesCurrentAbstract
Operating lease liabilities - current		$ 23.6
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]		us-gaap:LiabilitiesNoncurrentAbstract	us-gaap:LiabilitiesNoncurrentAbstract
Operating lease liabilities - non-current		$ 103	$ 0
Operating Lease, Liability		126.6
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year		28.7
Lessee, Operating Lease, Liability, Payments, Due Year Two		27.7
Lessee, Operating Lease, Liability, Payments, Due Year Three		24.4
Lessee, Operating Lease, Liability, Payments, Due Year Four		17.7
Lessee, Operating Lease, Liability, Payments, Due Year Five		11.9
Lessee, Operating Lease, Liability, Payments, Due after Year Five		39.9
Lessee, Operating Lease, Liability, Payments, Due		150.3
Lessee, Operating Lease, Liability, Undiscounted Excess Amount		23.7
Operating Leases, Future Minimum Payments, Due Next Twelve Months			28.3
Operating Leases, Future Minimum Payments, Due in Two Years			29
Operating Leases, Future Minimum Payments, Due in Three Years			28.1
Operating Leases, Future Minimum Payments, Due in Four Years			25.4
Operating Leases, Future Minimum Payments, Due in Fine Years			19.2
Operating Leases, Future Minimum Payments, Due Thereafter			77.3
Operating Leases, Future Minimum Payments Due			207.3
De-recognition of right of use asset		23.1
Operating Lease, Cost		42
Variable Lease, Cost		5.1
Short-term Lease, Cost		7.5
Operating Leases, Rent Expense, Net			$ 40.1	$ 41.3
Operating Lease, Payments		29.6
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		$ 5.6
Operating Lease, Weighted Average Remaining Lease Term		7 years
Operating Lease, Weighted Average Discount Rate, Percent		4.40%
De-recognition of lease liability		$ 23.1
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]		us-gaap:OtherAssets	us-gaap:OtherAssets
Industrial Property
Lessee, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Due			$ 36
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract		1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract		56 years
Other Liabilities
Lessee, Lease, Description [Line Items]
Operating Lease, Liability		$ 126.6
Accounting Standards Update 2016-02 | Right-of-use assets
Lessee, Lease, Description [Line Items]
Adoption of accounting standards updates	$ 158.1
Accounting Standards Update 2016-02 | Lease liabilities
Lessee, Lease, Description [Line Items]
Adoption of accounting standards updates	$ 168.2

Long Term Debt (Details)

Long Term Debt (Details)	Oct. 21, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Oct. 11, 2019USD ($)	Oct. 01, 2018USD ($)
Debt Instrument
Capital lease			$ 0	$ 100,000								$ 0	$ 100,000
Long-term Debt and Capital Lease Obligations, Including Current Maturities			7,049,700,000	7,119,300,000								7,049,700,000	7,119,300,000
Current portion of long-term debt			64,900,000	13,500,000								64,900,000	13,500,000
Unamortized Debt Issuance Expense			62,600,000	69,000,000								62,600,000	69,000,000
Plus: Unamortized premium			36,800,000	29,200,000								36,800,000	29,200,000
Total long-term debt			$ 6,959,000,000	7,066,000,000								$ 6,959,000,000	7,066,000,000
Debt Covenant, Leverage Ratio			4.25									4.25
Debt Covenant, Percentage of Revolving Credit Commitments			30.00%									30.00%
Gross Repayments of Long-term debt												$ 4,349,100,000	923,100,000	$ 919,800,000
Loss on extinguishment of debt, net												72,900,000	6,100,000	31,100,000
Premium and Debt Extinguishment Costs Paid												49,800,000	0	33,700,000
Payments of Debt Issuance Costs												$ 45,300,000	16,300,000	24,900,000
Debt Instruments, Covenant Compliance, Percentage of Revolving Credit Commitments			30.00%									30.00%
Loss on extinguishment of debt												$ 2,700,000	(124,600,000)
Repayments of Long-term Debt												4,349,100,000	919,100,000	912,100,000
Refund of debt issuance costs												15,300,000	7,800,000	0
Senior Notes | 5.50% Senior Notes Maturing in December 2029
Debt Instrument
Long-term Debt			$ 750,000,000	750,000,000								$ 750,000,000	750,000,000
Senior Notes				750,000,000									750,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.50%									5.50%
Debt Instrument, Increase, Additional Borrowings				743,000,000
Payments of Debt Issuance Costs				7,000,000
Senior Notes | 5.625% Senior Notes Maturing January 2028
Debt Instrument
Long-term Debt			$ 940,900,000	940,900,000								$ 940,900,000	940,900,000
Senior Notes						$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.625%									5.625%
Gross Repayments of Long-term debt													20,000,000	39,100,000
Debt Instrument, Increase, Additional Borrowings						990,600,000
Payments of Debt Issuance Costs						$ 9,400,000
Senior Notes | 5.50% Senior Notes maturing March 2025
Debt Instrument
Long-term Debt			$ 0	1,000,000,000								$ 0	1,000,000,000
Senior Notes									$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.50%									5.50%
Gross Repayments of Long-term debt												$ 1,000,000,000
Senior Notes | 5.75% Senior Notes Maturing March 2027
Debt Instrument
Long-term Debt			$ 1,299,300,000	1,299,300,000								$ 1,299,300,000	1,299,300,000
Senior Notes									$ 750,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.75%						5.75%			5.75%
Gross Repayments of Long-term debt													27,000,000	173,700,000
Senior Notes | 8.00% Senior Notes Maturing in July 2025
Debt Instrument
Long-term Debt			$ 0	122,200,000								$ 0	122,200,000
Senior Notes											$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage			8.00%									8.00%
Gross Repayments of Long-term debt												$ 122,200,000		15,300,000
Debt Instrument, Increase, Additional Borrowings											396,000,000
Payments of Debt Issuance Costs											$ 4,000,000
Senior Notes | 5.50% and 5.75% Senior Notes
Debt Instrument
Debt Instrument, Increase, Additional Borrowings									$ 1,725,400,000
Payments of Debt Issuance Costs									$ 24,600,000
Senior Notes | Additional Issuance of 5.75% Senior Notes Maturing in March 2027
Debt Instrument
Senior Notes							$ 750,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.75%									5.75%
Debt Instrument, Issuance Price, Percentage of Par Value							105.50%
Debt Instrument, Increase, Additional Borrowings							$ 784,000,000
Payments of Debt Issuance Costs							7,200,000
Senior Notes | 5.00% Senior Notes Maturing in August 2026
Debt Instrument
Long-term Debt			$ 1,697,300,000	1,697,300,000								$ 1,697,300,000	1,697,300,000
Senior Notes										$ 1,750,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.00%									5.00%
Gross Repayments of Long-term debt													13,000,000	39,700,000
Debt Instrument, Increase, Additional Borrowings										1,725,700,000
Payments of Debt Issuance Costs										$ 24,300,000
Payment of debt modification costs in connection with debt consents													8,400,000
Senior Notes | 4.625% Senior Notes Maturing in April 2030
Debt Instrument
Long-term Debt			$ 1,650,000,000	0								$ 1,650,000,000	0
Debt Instrument, Interest Rate, Stated Percentage			4.625%									4.625%
Senior Notes | Original Issuance of 4.625% Senior Notes Maturing in April 2030
Debt Instrument
Long-term Debt			$ 1,250,000,000									$ 1,250,000,000
Debt Instrument, Increase, Additional Borrowings												1,241,000,000
Payments of Debt Issuance Costs												9,000,000
Senior Notes | Additional Issuance of 4.625% Senior Notes Maturing in April 2030
Debt Instrument
Long-term Debt			$ 400,000,000									400,000,000
Debt Instrument, Issuance Price, Percentage of Par Value			105.50%
Debt Instrument, Increase, Additional Borrowings												417,500,000
Payments of Debt Issuance Costs												4,500,000
Senior Notes | 6.00% Senior Notes
Debt Instrument
Gross Repayments of Long-term debt														630,000,000
Capital Lease Obligations
Debt Instrument
Gross Repayments of Long-term debt													100,000
Revolving Credit Facility
Debt Instrument
Debt Covenant, Maximum Undischarged Judgments			$ 100,000,000									100,000,000
Gross Repayments of Long-term debt												$ 500,000,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage												0.25%
Line of Credit Facility, Current Borrowing Capacity			750,000,000									$ 750,000,000
Letters of Credit Outstanding, Amount			18,800,000									18,800,000
Line of Credit Facility, Remaining Borrowing Capacity			$ 731,200,000									731,200,000
Proceeds from Lines of Credit												$ 500,000,000
Revolving Credit Facility | High-End Ratio
Debt Instrument
Debt Covenant, Leverage Ratio			3									3
Revolving Credit Facility | Low-End Ratio
Debt Instrument
Debt Covenant, Leverage Ratio			1.50									1.50
Revolving Credit Facility | Minimum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage												0.25%
Revolving Credit Facility | Maximum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage												0.375%
Line of Credit
Debt Instrument
Line of Credit Facility, Current Borrowing Capacity			$ 75,000,000									$ 75,000,000
Credit Agreement
Debt Instrument
Gross Repayments of Long-term debt												0
Payments of Debt Issuance Costs												3,600,000
2020 Bridge Loan
Debt Instrument
Gross Repayments of Long-term debt												1,225,000,000
Payments of Debt Issuance Costs												19,100,000
Refund of debt issuance costs	$ 15,300,000
2018 Bridge Loan
Debt Instrument
Gross Repayments of Long-term debt													0
Loans Payable to Bank		$ 625,000,000			$ 625,000,000									625,000,000
Debt Instrument, Basis Spread on Variable Rate Debt		4.50
Term Loan
Debt Instrument
Long-term Debt	1,309,500,000		0	$ 1,309,500,000								0	1,309,500,000
Gross Repayments of Long-term debt												1,309,500,000	$ 863,000,000	22,000,000
Debt Instrument, Interest Rate, Effective Percentage				4.04%									4.04%
Term Loan | Joinder No. 1 Term Loan
Debt Instrument
Loans Payable to Bank								$ 1,200,000,000
Proceeds from issuance of unsecured debt								1,200,000,000
Term Loan | Joinder No. 2 Term Loan
Debt Instrument
Loans Payable to Bank								$ 1,000,000,000
Proceeds from issuance of unsecured debt							$ 1,000,000,000
Municipal Bonds
Debt Instrument
Long-term Debt			8,500,000	$ 0								8,500,000	$ 0
Gross Repayments of Long-term debt												1,100,000
Premium from issuance of long-term debt												2,200,000
BellRing term B Facility
Debt Instrument
Long-term Debt			673,700,000	0								673,700,000	0
BellRing Revolving Credit Facility
Debt Instrument
Long-term Debt			30,000,000	$ 0								$ 30,000,000	$ 0
Base Rate | Revolving Credit Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												0.50%
Base Rate | Revolving Credit Facility | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												0.50%
Base Rate | Revolving Credit Facility | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												1.00%
Base Rate | Revolving Credit Facility | Median
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												0.75%
Base Rate | Term Loan
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate													1.00%
Base Rate | BellRing term B Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												4.00%
Eurodollar | Revolving Credit Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												1.50%
Eurodollar | Revolving Credit Facility | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												1.50%
Eurodollar | Revolving Credit Facility | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												2.00%
Eurodollar | Revolving Credit Facility | Median
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												1.75%
Eurodollar | Term Loan
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate													2.00%
Federal Funds | Revolving Credit Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												0.50%
One-Month Eurodollar | Revolving Credit Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												1.00%
Long-term debt held for sale | 2018 Bridge Loan
Debt Instrument
Proceeds from issuance of unsecured debt					$ 625,000,000
Payments of Debt Issuance Costs														10,400,000
Unamortized Debt Issuance Expense to be Reimbursed																$ 7,800,000
BellRing Brands, LLC | 2020 Bridge Loan
Debt Instrument
Loans Payable to Bank															$ 1,225,000,000
Proceeds from issuance of unsecured debt												$ 1,225,000,000
BellRing
Debt Instrument
Debt Instrument, Redemption Price, Percentage												98.00%
Proceeds from Debt, Net of Issuance Costs												$ 776,400,000
Debt Instrument, Unamortized Discount	14,000,000
BellRing | 2020 Bridge Loan
Debt Instrument
Gross Repayments of Long-term debt												1,225,000,000
Interest Costs Incurred												2,200,000
BellRing | BellRing term B Facility
Debt Instrument
Gross Repayments of Long-term debt												26,300,000
Loans Payable to Bank			$ 700,000,000									$ 700,000,000
Debt Instrument, Interest Rate, Effective Percentage			6.00%									6.00%
Debt Instrument, Periodic Payment, Principal												$ 8,750,000
Debt Instrument, Mandatory Prepayment, Excess Cash Flow												$ 28,800,000
BellRing | BellRing Revolving Credit Facility
Debt Instrument
Debt Covenant, Leverage Ratio			6									6
Debt Covenant, Maximum Undischarged Judgments			$ 65,000,000									$ 65,000,000
Gross Repayments of Long-term debt	20,000,000											$ 165,000,000
Debt Instrument, Interest Rate, Effective Percentage			5.25%									5.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage												0.50%
Line of Credit Facility, Current Borrowing Capacity			$ 200,000,000									$ 200,000,000
Letters of Credit Outstanding, Amount	$ 100,000,000
Line of Credit Facility, Remaining Borrowing Capacity			170,000,000									170,000,000
Proceeds from Lines of Credit												195,000,000
Line of Credit Facility, Maximum Borrowing Capacity			$ 20,000,000									$ 20,000,000
BellRing | BellRing Revolving Credit Facility | Less than or equal to 3.35
Debt Instrument
Debt Covenant, Leverage Ratio			3.35									3.35
BellRing | BellRing Revolving Credit Facility | Minimum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage												0.25%
BellRing | BellRing Revolving Credit Facility | Maximum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage												0.50%
BellRing | Term B Facility and BellRing Revolving Credit Facility
Debt Instrument
Payments of Debt Issuance Costs												$ 9,600,000
BellRing | Base Rate | BellRing Revolving Credit Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												3.25%
BellRing | Base Rate | BellRing Revolving Credit Facility | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												2.75%
BellRing | Base Rate | BellRing Revolving Credit Facility | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												3.25%
BellRing | Base Rate | BellRing Revolving Credit Facility | Median
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												3.00%
BellRing | Eurodollar | BellRing term B Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												5.00%
BellRing | Eurodollar | BellRing Revolving Credit Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												4.25%
BellRing | Eurodollar | BellRing Revolving Credit Facility | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												3.75%
BellRing | Eurodollar | BellRing Revolving Credit Facility | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												4.25%
BellRing | Eurodollar | BellRing Revolving Credit Facility | Median
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												4.00%
BellRing | Federal Funds | BellRing term B Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												0.50%
BellRing | One-Month Eurodollar | BellRing term B Facility
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate												1.00%
Selling, general and administrative expenses | Senior Notes | 5.00% Senior Notes Maturing in August 2026
Debt Instrument
Expense incurred in connection with debt consents													$ 1,300,000
Loss on extinguishment of debt, net
Debt Instrument
Debt Repurchased at a Discount												$ 0	(4,000,000)	(7,700,000)
Premium and Debt Extinguishment Costs Paid												49,800,000	0	33,700,000
Write off of Deferred Debt Issuance Cost												23,100,000	10,800,000	9,700,000
Write-off of Unamortized Debt Discount/(Premium)												0	(700,000)	(4,600,000)
Loss on extinguishment of debt, net | Senior Notes | 5.625% Senior Notes Maturing January 2028
Debt Instrument
Debt Repurchased at a Discount													(1,300,000)	(2,100,000)
Premium and Debt Extinguishment Costs Paid													0	0
Write off of Deferred Debt Issuance Cost													200,000	400,000
Write-off of Unamortized Debt Discount/(Premium)													0	0
Loss on extinguishment of debt, net | Senior Notes | 5.50% Senior Notes maturing March 2025
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												41,300,000
Write off of Deferred Debt Issuance Cost												8,700,000
Write-off of Unamortized Debt Discount/(Premium)												0
Loss on extinguishment of debt, net | Senior Notes | 5.75% Senior Notes Maturing March 2027
Debt Instrument
Debt Repurchased at a Discount													(1,500,000)	(3,100,000)
Premium and Debt Extinguishment Costs Paid													0	0
Write off of Deferred Debt Issuance Cost													300,000	1,900,000
Write-off of Unamortized Debt Discount/(Premium)													(700,000)	(4,600,000)
Loss on extinguishment of debt, net | Senior Notes | 8.00% Senior Notes Maturing in July 2025
Debt Instrument
Debt Repurchased at a Discount												0		0
Premium and Debt Extinguishment Costs Paid												8,500,000		2,000,000
Write off of Deferred Debt Issuance Cost												700,000		100,000
Write-off of Unamortized Debt Discount/(Premium)												0		0
Loss on extinguishment of debt, net | Senior Notes | 5.00% Senior Notes Maturing in August 2026
Debt Instrument
Debt Repurchased at a Discount													(1,200,000)	(2,500,000)
Premium and Debt Extinguishment Costs Paid													0	0
Write off of Deferred Debt Issuance Cost													100,000	400,000
Write-off of Unamortized Debt Discount/(Premium)													0	0
Loss on extinguishment of debt, net | Senior Notes | 6.00% Senior Notes
Debt Instrument
Debt Repurchased at a Discount														0
Premium and Debt Extinguishment Costs Paid														30,800,000
Write off of Deferred Debt Issuance Cost														6,500,000
Write-off of Unamortized Debt Discount/(Premium)														0
Loss on extinguishment of debt, net | Capital Lease Obligations
Debt Instrument
Debt Repurchased at a Discount													0
Premium and Debt Extinguishment Costs Paid													0
Write off of Deferred Debt Issuance Cost													0
Write-off of Unamortized Debt Discount/(Premium)													0
Loss on extinguishment of debt, net | Revolving Credit Facility
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												0
Write off of Deferred Debt Issuance Cost												0
Write-off of Unamortized Debt Discount/(Premium)												0
Loss on extinguishment of debt, net | Credit Agreement
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												0
Write off of Deferred Debt Issuance Cost												800,000
Write-off of Unamortized Debt Discount/(Premium)												0
Loss on extinguishment of debt, net | 2020 Bridge Loan
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												0
Write off of Deferred Debt Issuance Cost												3,800,000
Write-off of Unamortized Debt Discount/(Premium)												0
Loss on extinguishment of debt, net | 2018 Bridge Loan
Debt Instrument
Debt Repurchased at a Discount													0
Premium and Debt Extinguishment Costs Paid													0
Write off of Deferred Debt Issuance Cost													2,600,000
Write-off of Unamortized Debt Discount/(Premium)													0
Loss on extinguishment of debt, net | Term Loan
Debt Instrument
Debt Repurchased at a Discount												0	0	0
Premium and Debt Extinguishment Costs Paid												0	0	900,000
Write off of Deferred Debt Issuance Cost												9,100,000	7,600,000	400,000
Write-off of Unamortized Debt Discount/(Premium)												0	0	$ 0
Loss on extinguishment of debt, net | Municipal Bonds
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												0
Write off of Deferred Debt Issuance Cost												0
Write-off of Unamortized Debt Discount/(Premium)												0
Loss on extinguishment of debt, net | BellRing | BellRing term B Facility
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												0
Write off of Deferred Debt Issuance Cost												0
Write-off of Unamortized Debt Discount/(Premium)												0
Loss on extinguishment of debt, net | BellRing | BellRing Revolving Credit Facility
Debt Instrument
Debt Repurchased at a Discount												0
Premium and Debt Extinguishment Costs Paid												0
Write off of Deferred Debt Issuance Cost												0
Write-off of Unamortized Debt Discount/(Premium)												$ 0
Write off of debt issuance costs and other expenses | 8th Avenue | Loss on extinguishment of debt, net
Debt Instrument
Write off of Debt Issuance Costs													$ 2,600,000

Commitments and Contingencies (

Commitments and Contingencies (Details)	Dec. 08, 2016USD ($)	Sep. 30, 2020USD ($)plaintiff_groupdefendant	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Jan. 12, 2018$ / shares
Loss Contingencies [Line Items]
Accrued legal settlements, current		$ 13,200,000	$ 16,100,000
Bob Evans Farms
Loss Contingencies [Line Items]
Business Acquisition, Share Price | $ / shares					$ 77
Payments to appraisal rights holders, including interest			257,600,000
Lease Guarantee, Number of Properties		143
Current annual rent of guaranteed leases		$ 13,900,000
Lease Guarantee, Interest rate increase		1.50%
Lease Guarantee, Remaining Lease Term		17 years
Michael Foods
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number		22
Loss Contingency, Pending Claims, Other Defendants | defendant		20
Loss Contingency, Pending Claims, Number of Plaintiff Groups | plaintiff_group		3
Litigation Settlement	$ 75,000,000
Accrued legal settlements, current		$ 3,500,000	6,200,000
Other Current Liabilities | Bob Evans Farms
Loss Contingencies [Line Items]
Accrued legal settlements, current			19,100,000
Selling, general and administrative expenses | Michael Foods
Loss Contingencies [Line Items]
Litigation Settlement, Expense			5,000,000	$ 8,300,000
SG&A and Interest expense, net | Bob Evans Farms
Loss Contingencies [Line Items]
Litigation Settlement, Expense			$ 9,700,000
Interest expense, net | Bob Evans Farms
Loss Contingencies [Line Items]
Litigation Settlement, Expense				$ 13,400,000

Pension and Other Postretirem_3

Pension and Other Postretirement Benefits - Change in Projected Benefit Obligation, Fair Value of Plan Assets, and Net Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Amounts recognized in assets or liabilities [Abstract]
Other liabilities	$ (77.7)	$ (66)
UNITED STATES
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	2.79%	3.20%
CANADA
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	2.78%	2.86%
Rate of compensation increase	2.75%	2.75%
Pension Benefits | UNITED STATES
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	3.01%	3.32%
Rate of compensation increase	3.00%	3.00%
Pension Benefits | Foreign Plan
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	$ 780.5	$ 691.2
Service cost	0	5.6	$ 6.7
Interest cost	14.7	18.9	19.6
Plan participants' contributions	0	2.2
Prior service cost	11.4	1.5
Actuarial (gain) loss	17.6	126.6
Benefits Paid	(25.9)	(26.2)
Currency translation	36.1	(39.3)
Benefit obligation at end of period	834.4	780.5	691.2
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	946.9	844.5
Actual return on plan assets	28.1	169.9
Employer contributions	0	4.8
Plan participants' contributions	0	2.2
Benefits Paid	(25.9)	(26.2)
Currency translation	44.1	(48.3)
Fair value of plan assets at end of period	993.2	946.9	844.5
Defined benefit plan, funded status of plan [Abstract]
Funded status	158.8	166.4
Amounts recognized in assets or liabilities [Abstract]
Other assets	158.8	166.4
Other liabilities	0	0
Net amount recognized	158.8	166.4
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	(32.3)	(46.5)
Prior service cost (credit)	11.5	0.1
Total	$ (20.8)	$ (46.4)
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	1.73%	1.84%
Rate of compensation increase	2.65%	2.55%
Pension Benefits | North America
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	$ 121.5	$ 100.9
Service cost	4.3	3.7	4.2
Interest cost	3.7	4.1	3.6
Plan participants' contributions	0.5	0.5
Prior service cost	0	0
Actuarial (gain) loss	6.6	17.3
Benefits Paid	(5.4)	(4.6)
Currency translation	(0.1)	(0.4)
Benefit obligation at end of period	131.1	121.5	100.9
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	119.7	114.1
Actual return on plan assets	6.4	9.8
Employer contributions	0.4	0.3
Plan participants' contributions	0.5	0.5
Benefits Paid	(5.4)	(4.6)
Currency translation	(0.1)	(0.4)
Fair value of plan assets at end of period	121.5	119.7	114.1
Defined benefit plan, funded status of plan [Abstract]
Funded status	(9.6)	(1.8)
Amounts recognized in assets or liabilities [Abstract]
Other assets	0.2	0.3
Other liabilities	(9.8)	(2.1)
Net amount recognized	(9.6)	(1.8)
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	28.2	23.4
Prior service cost (credit)	0.3	0.4
Total	28.5	23.8
Weighted-average assumptions used to determine benefit obligation [Abstract]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	$ 129.3	$ 119.7
Pension Benefits | CANADA
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	2.71%	2.84%
Rate of compensation increase	2.75%	2.75%
Pension Benefits | Other International
Weighted-average assumptions used to determine benefit obligation [Abstract]
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	$ 831.1	$ 776.4
Other Benefits | North America
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	66.4	55.2
Service cost	0.6	0.4	0.5
Interest cost	1.9	2.1	2.1
Actuarial (gain) loss	4.6	11.5
Benefits Paid	(2.7)	(2.6)
Currency translation	(0.1)	(0.2)
Benefit obligation at end of period	70.7	66.4	$ 55.2
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	0
Employer contributions	2.7	2.6
Benefits Paid	(2.7)	(2.6)
Fair value of plan assets at end of period	0	0
Defined benefit plan, funded status of plan [Abstract]
Funded status	(70.7)	(66.4)
Amounts recognized in assets or liabilities [Abstract]
Other current liabilities	(2.8)	(2.5)
Other liabilities	(67.9)	(63.9)
Net amount recognized	(70.7)	(66.4)
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	14.3	10.3
Prior service cost (credit)	(14.7)	(19.4)
Total	$ (0.4)	$ (9.1)

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	$ 36.8	$ 12.5	$ (5)
Pension Benefits | Foreign Plan
Components of net periodic benefit cost [Abstract]
Service cost	0	5.6	6.7
Interest cost	14.7	18.9	19.6
Expected return on plan assets	(24.6)	(28.8)	(31.7)
Recognized curtailment	0	1.5	0
Net periodic benefit cost	$ (9.9)	$ (2.8)	$ (5.4)
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	1.84%	2.81%	2.72%
Rate of compensation increase	2.55%	2.75%	2.70%
Expected return on plan assets	2.53%	3.51%	3.56%
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	$ 14.2	$ (14.4)	$ 8.2
Prior Service Cost	11.4	1.5	0
Recognized Curtailment	0	(1.5)	0
Total recognized in other comprehensive income or loss (before tax effects)	25.6	(14.4)	8.2
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	0
Pension Benefits | North America
Components of net periodic benefit cost [Abstract]
Service cost	4.3	3.7	4.2
Interest cost	3.7	4.1	3.6
Expected return on plan assets	(6.4)	(6.4)	(4.4)
Recognized net actuarial loss	1.8	0	1.1
Recognized prior service cost	0.1	0.1	0.1
Net periodic benefit cost	3.5	1.5	4.6
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	6.6	13.9	(3.7)
Recognized loss	(1.8)	0	(1.1)
Recognized prior service cost	(0.1)	(0.1)	(0.1)
Total recognized in other comprehensive income or loss (before tax effects)	4.7	$ 13.8	$ (4.9)
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0.2
Pension Benefits | CANADA
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	2.84%	3.53%	3.63%
Rate of compensation increase	2.75%	2.75%	2.69%
Expected return on plan assets	5.75%	5.75%	6.00%
Pension Benefits | UNITED STATES
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	3.32%	4.30%	3.86%
Rate of compensation increase	3.00%	3.00%	3.00%
Expected return on plan assets	5.53%	5.74%	5.46%
Other Benefits | North America
Components of net periodic benefit cost [Abstract]
Service cost	$ 0.6	$ 0.4	$ 0.5
Interest cost	1.9	2.1	2.1
Recognized net actuarial loss	0.6	0	0.3
Recognized prior service cost	(4.7)	(4.7)	(4.7)
Net periodic benefit cost	(1.6)	(2.2)	(1.8)
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	4.6	11.5	(9.9)
Recognized loss	(0.6)	0	(0.3)
Recognized prior service cost	4.7	4.7	4.7
Currency translation	0	0	0.4
Total recognized in other comprehensive income or loss (before tax effects)	$ 8.7	$ 16.2	$ (5.1)
Other Benefits | CANADA
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	2.86%	3.54%	3.69%
Rate of compensation increase	2.75%	2.75%	2.75%
Other Benefits | UNITED STATES
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	3.20%	4.27%	3.77%

Pension and Other Postretirem_5

Pension and Other Postretirement Benefits - Pension Plan Assets Measured at Fair Value on a Recurring Basis (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Foreign Plan
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Actual allocations, index funds	34.40%	33.70%
Pension plan's assets at fair value	$ 993.2	$ 946.9	$ 844.5
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	899.8	864.7
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	93.4	82.2
Foreign Plan | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	899.8	864.7
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	899.8	864.7
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	0	0
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	$ 0	$ 0
Foreign Plan | Fixed Income Funds and Bonds
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	67.10%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	69.60%	62.50%
Foreign Plan | Fixed Income Funds and Bonds | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 642.1	$ 554.8
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Fixed Income Funds and Bonds | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Fixed Income Funds and Bonds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	49.2	37
Foreign Plan | Fixed Income Funds and Bonds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 642.1	$ 554.8
Foreign Plan | Liability Hedging Instruments
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30.20%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	27.20%	30.10%
Foreign Plan | Liability Hedging Instruments | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 241.6	$ 258.6
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Liability Hedging Instruments | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Liability Hedging Instruments | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	28.6	26
Foreign Plan | Liability Hedging Instruments | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 241.6	$ 258.6
Foreign Plan | Real assets
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.50%	1.70%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.30%
Foreign Plan | Real assets | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	$ 0	$ 0
Foreign Plan | Real assets | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Real assets | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	$ 12.8	$ 16.5
Foreign Plan | Cash and Cash Equivalents
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.20%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.90%	5.70%
Foreign Plan | Cash and Cash Equivalents | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 16.1	$ 51.3
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Cash and Cash Equivalents | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Foreign Plan | Cash and Cash Equivalents | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	2.8	2.7
Foreign Plan | Cash and Cash Equivalents | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 16.1	$ 51.3
North America
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Actual allocations, index funds	99.50%	99.60%
Pension plan's assets at fair value	$ 121.5	$ 119.7	$ 114.1
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	17.3	16.4
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	104.2	103.3
North America | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	1.3	1.2
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	1.3	1.2
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
North America | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	16	15.2
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	16	15.2
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	$ 0	$ 0
North America | Equities
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	55.60%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	58.30%	46.40%
North America | Equities | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 0	$ 0
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
North America | Equities | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	10.5	9.9
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
North America | Equities | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	60.3	45.6
North America | Equities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 10.5	$ 9.9
North America | Fixed Income Funds and Bonds
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.80%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	40.60%	47.30%
North America | Fixed Income Funds and Bonds | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 0	$ 0
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
North America | Fixed Income Funds and Bonds | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	5.5	5.3
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
North America | Fixed Income Funds and Bonds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	43.8	51.3
North America | Fixed Income Funds and Bonds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 5.5	$ 5.3
North America | Real assets
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.60%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	0.10%	5.30%
North America | Real assets | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	$ 0	$ 0
North America | Real assets | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
North America | Real assets | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	$ 0.1	$ 6.4
North America | Cash and Cash Equivalents
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	1.00%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.00%	1.00%
North America | Cash and Cash Equivalents | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 1.3	$ 1.2
North America | Cash and Cash Equivalents | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
North America | Cash and Cash Equivalents | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 1.3	$ 1.2

Pension and Other Postretirem_6

Pension and Other Postretirement Benefits - Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates (Details) - Other Benefits	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%	5.00%
Participants Over and Under 65
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	6.10%	6.30%
CANADA
Defined Benefit Plan Disclosure
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.50%	4.50%
CANADA | Participants Over and Under 65
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	5.00%	5.50%

Pension and Other Postretirem_7

Pension and Other Postretirement Benefits - Expected Future Benefit Payments and Related Federal Subsidy Receipts (Details) $ in Millions	Sep. 30, 2020USD ($)
Pension Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Year 1	$ 25.2
Year 2	26.3
Year 3	27.3
Year 4	28.5
Year 5	29.8
Year 6 and thereafter	168.9
Other Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Year 1	2.9
Year 2	3.2
Year 3	3.5
Year 4	3.6
Year 5	3.6
Year 6 and thereafter	18.3
Disclosure of Expected Gross Prescription Drug Subsidy Receipts [Abstract]
Year 1	0.1
Year 2	0.1
Year 3	0.1
Year 4	0.2
Year 5	0.2
Years 6-10	$ 1

Pension and Other Postretirem_8

Pension and Other Postretirement Benefits - Defined contribution plan expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Retirement Benefits [Abstract]
401K Matching Contributions	$ 18.4	$ 17.9	$ 19.6

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans Narrative (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Award [Line Items]
Matching contribution on Director Deferred Compensation	33.30%
Post 2012 Long-Term Incentive Plan | Post Awards
Restricted Stock Awards [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	6.5
Post 2016 Long-Term Incentive Plan | Post Awards
Restricted Stock Awards [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2.4
Post 2019 Long Term Incentive Plan | Post Awards
Restricted Stock Awards [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	1.2
Post Long-Term Incentive Plans
Share-based Payment Award [Line Items]
Share-based Compensation Arrangement , Maximum Award Vesting Period	10 years
Stock Based Compensation Awards [Abstract]
Stock-based Compensation Expense	$ 47.1	$ 39.7	$ 33.8
Recognized deferred tax beneft	7	$ 6.6	$ 7.8
Compensation cost related to nonvested awards not yet recognized	$ 59.7
Awards not yet recognized. weighted average period to be recognized	1 year 8 months 12 days

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans - Stock Appreciation Rights Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Post Stock Settled
Stock Appreciation Rights
Outstanding	135,000	136,031
Granted	0
Exercised	(1,031)
Forfeited	0
Expired	0
Vested And Expected To Vest	135,000
Exercisable	135,000
Outstanding, Weighted Average Exercise Price	$ 42.12	$ 41.94
Granted, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	18.10
Forfeited, Weighted Average Exercise Price	0
Expired, Weighted Average Exercise Price	0
Vested And Expected To Vest, Weighted Average Exercise Price	42.12
Exercisable, Weighted Average Exercise Price	$ 42.12
Outstanding, Weighted Average Remaining Contractual Term	2 years 9 months
Vested And Expected To Vest, Outstanding, Weighted Average Remaining Contractual Term	2 years 9 months
Exercisable, Weighted Average Remaining Contractual Term	2 years 9 months
Outstanding, Intrinsic Value	$ 5.9
Vested And Expected To Vest, Outstanding, Aggregate Intrinsic Value	5.9
Exercisable, Aggregate Intrinsic Value	5.9
Exercised, Total Intrinsic Value	$ 0.1		$ 0.1
Post Cash Settled
Stock Appreciation Rights
Outstanding	0	2,500
Granted	0
Exercised	(2,500)
Forfeited	0
Expired	0
Vested And Expected To Vest	0
Exercisable	0
Outstanding, Weighted Average Exercise Price		$ 18.10
Granted, Weighted Average Exercise Price	$ 0
Exercised, Weighted Average Exercise Price	18.10
Forfeited, Weighted Average Exercise Price	0
Expired, Weighted Average Exercise Price	$ 0
Expected Term		0 years	0 years
Expected Volatility Rate		24.80%	21.50%
Risk Free Interest Rate		1.80%	2.60%
Expected Dividend Rate		0.00%	0.00%
Fair Value Of Awards, Per Share		$ 87.84	$ 79.94
Exercised, Total Intrinsic Value	$ 0.2		$ 5

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans - Stock Option award activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Award [Line Items]
Proceeds from Stock Options Exercised	$ 3.9	$ 112.6	$ 5.7
Post Stock Options
Share-based Payment Award [Line Items]
Exercised, Total Intrinsic Value	$ 5.5	$ 148.2	$ 4.7
Outstanding	1,699,280	1,758,026
Granted	30,504
Exercised	(89,250)
Forfeited	0
Expired	0
Vested and Expected to Vest	1,699,280
Exercisable	1,509,246
Outstanding, Weighted Average Exercise Price	$ 59.63	$ 58.03
Granted, Weighted Average Exercise Price	106.51
Exercised, Weighted Average Exercise Price	44.11
Forfeited, Weighted Average Exercise Price	0
Expired, Weighted Average Exercise Price	0
Vested and Expected to Vest, Weighted Average Exercise Price	59.63
Exercisable, Weighted Average Exercise Price	$ 55.91
Outstanding, Weighted Average Remaining Contractual Term	5 years 2 months 15 days
Vested and Expected to Vest, Weighted Average Remaining Contractual Term	5 years 2 months 15 days
Exercisable, Weighted Average Remaining Contractual Term	4 years 10 months 17 days
Outstanding, Intrinsic Value	$ 46.1
Vested and Expected to Vest, Aggregate Intrinsic Value	46.1
Exercisable, Intrinsic Value	$ 45.6
Expected Term	6 years 6 months	6 years 6 months	6 years 6 months
Expected Volatility Rate	29.20%	29.70%	30.70%
Risk Free Interest Rate	1.80%	3.10%	2.20%
Expected Dividend Rate	0.00%	0.00%	0.00%
Fair value per option	$ 35.32	$ 33.82	$ 28.52
Proceeds from Stock Options Exercised	$ 3.9	$ 112.6	$ 5.7

Stock-Based Compensation Plan_5

Stock-Based Compensation Plans - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Post Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	929,933	1,013,939
Granted	351,786
Vested	(413,820)
Forfeited	(21,972)
Grant date value per share	$ 89.14	$ 81.27	$ 71.94
Granted, Weighted Average Exercise Price	103.97
Vested, Weighted Average Exercise Price	82.16
Forfeited, Weighted Average Exercise Price	$ 95.08
Fair value of restricted stock awards vested	$ 42.1	$ 24.9	$ 17.4
Post Cash Settled
Share-based Payment Award [Line Items]
Grant date price of restricted stock units valued at greater of current stock price or grant price	$ 51.43
Nonvestsed restricted stock awards	39,200	49,000
Granted	0
Vested	(9,800)
Forfeited	0
Grant date value per share	$ 51.43	$ 51.43
Granted, Weighted Average Exercise Price	0
Vested, Weighted Average Exercise Price	51.43
Forfeited, Weighted Average Exercise Price	$ 0
Total Share-based Liabilities Paid	$ 0.9	$ 1.1	$ 3.2
BOD Grant
Share-based Payment Award [Line Items]
Granted			13,300
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number			11,400
Non-employee director share-based compensation			$ 0.9

Stock-Based Compensation Plan_6

Stock-Based Compensation Plans Performance Restricted Stock Units (Details) - $ / shares	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Post Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	173,707	82,871
Granted	90,836
Granted, Weighted Average Exercise Price	$ 138.10	$ 122.34	$ 97.74
Vested	0
Vested, Weighted Average Exercise Price	$ 0
Forfeited, Weighted Average Exercise Price	$ 0
Forfeited	0
Grant date value per share	$ 126	$ 112.75
Minimum
Share-based Payment Award [Line Items]
Total Award Range	0.00%
Maximum
Share-based Payment Award [Line Items]
Total Award Range	200.00%
Performance-Based Restricted Stock Units
Share-based Payment Award [Line Items]
Expected Term	3 years	3 years	3 years
Expected Volatility Rate	22.20%	24.20%	31.80%
Risk Free Interest Rate	1.60%	2.90%	1.80%

Stock-Based Compensation Plan_7

Stock-Based Compensation Plans - BellRing (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
BRBR Stock Options
Share-based Payment Award [Line Items]
Outstanding	96,000	0
Outstanding, Weighted Average Exercise Price	$ 19.31	$ 0
Granted	96,000
Granted, Weighted Average Exercise Price	$ 19.31
Exercised	0
Exercised, Weighted Average Exercise Price	$ 0
Forfeited	0
Forfeited, Weighted Average Exercise Price	$ 0
Expired	0
Expired, Weighted Average Exercise Price	$ 0
Outstanding, Weighted Average Remaining Contractual Term	9 years 1 month 24 days
Outstanding, Intrinsic Value	$ 0.1
Vested and Expected to Vest	96,000
Vested and Expected to Vest, Weighted Average Exercise Price	$ 19.31
Vested and Expected to Vest, Weighted Average Remaining Contractual Term	9 years 1 month 24 days
Vested and Expected to Vest, Aggregate Intrinsic Value	$ 0.1
Exercisable	0
Expected Term	6 years 6 months
Expected Volatility Rate	38.50%
Risk Free Interest Rate	1.60%
Expected Dividend Rate	0.00%
Fair value per option	$ 7.92
BRBR Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	385,232	0
Grant date value per share	$ 19.39	$ 0
Granted	395,232
Granted, Weighted Average Exercise Price	$ 19.39
Vested	0
Vested, Weighted Average Exercise Price	$ 0
Forfeited	(10,000)
Forfeited, Weighted Average Exercise Price	$ 19.31
BellRing 2019 Long-Term Incentive Plan [Member]
Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2,000,000
Stock-based Compensation Expense	$ 2.5
Recognized deferred tax beneft	0.6
Compensation cost related to nonvested awards not yet recognized	$ 5.7
Awards not yet recognized. weighted average period to be recognized	2 years 8 months 12 days
Share-based Compensation Arrangement , Maximum Award Vesting Period	10 years

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Purchases of treasury stock	$ 587.8	$ 330.8	$ 218.7
Cash paid for share repurchase contracts	46.4	$ 0	$ 0
Share Repurchase Contracts, Shares Expected to be Repurchased, Next Fiscal Period	0.6
Share Repurchase Contracts, Cash Expected to be Received, Next Fiscal Period	$ 47.5
Preferred Stock
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired	0
Common Stock
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired	6.1	3.3	2.8
Treasury Stock Acquired, Average Cost Per Share	$ 97.67	$ 98.78	$ 76.21
Purchases of treasury stock	$ 587.8	$ 330.8	$ 218.7
Payments for accrued repurchases of common stock	$ 7.4	$ 8.7

Segments (Details)

Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Entity-Wide Revenue, Major Customer, Percentage									20.90%	20.90%	17.60%
Net Sales	$ 1,411.3	$ 1,336.4	$ 1,494.2	$ 1,456.8	$ 1,442.8	$ 1,439.2	$ 1,387.8	$ 1,411.3	$ 5,698.7	$ 5,681.1	$ 6,257.2
Operating Profit									700.5	781	573.5
Gain on sale of business					0.7	0	(2.6)	(124.7)	0	(126.6)	0
Impairment of goodwill and other intangible assets					63.3	$ 0	$ 0	$ 0	0	63.3	124.9
Interest expense, net									388.6	322.4	387.3
Loss on extinguishment of debt, net									72.9	6.1	31.1
Expense (income) on swaps, net									187.1	306.6	(95.6)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									63.4	159.1	264.7
Property, Plant and Equipment, Additions									234.6	273.9	225
Depreciation and amortization									370.3	379.6	398.4
Assets	12,146.7				11,951.6				$ 12,146.7	$ 11,951.6	$ 13,057.5
Non-US
Segment Reporting Information [Line Items]
Sales to Foreign Countries as a Percentage of Total Net Sales									13.90%	12.80%	12.90%
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries	294.2				279				$ 294.2	$ 279
Operating Segments
Segment Reporting Information [Line Items]
Net Sales									5,698.7	5,681.1	$ 6,257.2
Operating Profit									821	900.5	849.2
Depreciation and amortization									366.3	363.6	390.2
Operating Segments | Post Consumer Brands Segment
Segment Reporting Information [Line Items]
Net Sales									1,949.1	1,875.9	1,831.7
Operating Profit									393.5	337.1	329.2
Property, Plant and Equipment, Additions									67.4	62.1	51.5
Depreciation and amortization									112.4	117.4	122
Assets	3,291.7				3,296.3				3,291.7	3,296.3	3,391.7
Operating Segments | Weetabix Segment
Segment Reporting Information [Line Items]
Net Sales									440.4	418.2	423.4
Operating Profit									112.3	94.8	87.2
Property, Plant and Equipment, Additions									24.6	37.7	26.3
Depreciation and amortization									35.9	35	38.1
Assets	1,864.5				1,779.1				1,864.5	1,779.1	1,853.3
Operating Segments | Foodservice and Refrigerated Retail
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Additions									139.5	162.3	114.6
Assets	5,022				5,033.8				5,022	5,033.8	5,132.4
Operating Segments | Foodservice Segment
Segment Reporting Information [Line Items]
Net Sales									1,361.8	1,627.4	1,548.2
Operating Profit									25.6	198.4	157.6
Depreciation and amortization									119.6	111.8	105.4
Operating Segments | Refrigerated Retail Segment
Segment Reporting Information [Line Items]
Net Sales									961.2	907.3	790.9
Operating Profit									125.6	95.1	90
Depreciation and amortization									73.1	74.1	57.9
Operating Segments | BellRing Brands
Segment Reporting Information [Line Items]
Net Sales									988.3	854.4	827.5
Operating Profit									164	175.1	124.4
Property, Plant and Equipment, Additions									2.1	3.2	5
Depreciation and amortization									25.3	25.3	25.9
Assets	653.5				594				653.5	594	559.3
Operating Segments | Private Brands segment
Segment Reporting Information [Line Items]
Net Sales									0	0	848.9
Operating Profit									0	0	60.8
Property, Plant and Equipment, Additions									0	0	26.6
Depreciation and amortization									0	0	40.9
Assets	0				0				0	0	1,055.3
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Other Expenses									109	169.6	136.8
Property, Plant and Equipment, Additions									1	8.6	1
Depreciation and amortization									4	16	8.2
Assets	$ 1,315				$ 1,248.4				1,315	1,248.4	1,065.5
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Sales									(2.1)	(2.1)	(13.4)
Cereal and granola | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									2,388.7	2,293.3	2,351.2
Eggs and egg products | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									1,307.8	1,578.4	1,542.8
Side dishes (including potato products) | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									536.6	519.6	398.2
Cheese and dairy | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									253.2	234.6	248.6
Sausage | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									168.1	149.6	96
Protein-based products and supplements | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									988.7	854.7	827.5
Nut butters and dried fruit and nut | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									0	0	487.5
Pasta | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									0	0	258.4
Other | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									57.3	52.5	53
Product Eliminations
Segment Reporting Information [Line Items]
Net Sales									$ (1.7)	$ (1.6)	$ (6)

Summary Quarterly Financial I_2

Summary Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Quarterly Financial Information [Abstract]
Net Sales	$ 1,411.3	$ 1,336.4	$ 1,494.2	$ 1,456.8	$ 1,442.8	$ 1,439.2	$ 1,387.8	$ 1,411.3	$ 5,698.7	$ 5,681.1	$ 6,257.2
Gross Profit	440.3	436.8	438.8	471.5	452.2	462.1	451.3	426.5	1,787.4	1,792.1	1,854
(Gain) loss on sale of business					0.7	0	(2.6)	(124.7)	0	(126.6)	0
Impairment of goodwill and other intangible assets					63.3	0	0	0	0	63.3	124.9
Net earnings	57	36	(191.4)	99.2	(61.1)	16.2	44	125.6	0.8	124.7	467.3
Net Earnings (Loss) Available to Common Stockholders	$ 57	$ 36	$ (191.4)	$ 99.2	$ (61.1)	$ 16.2	$ 43	$ 123.6	$ 0.8	$ 121.7	$ 457.3
Basic earnings per common share (in usd per share)	$ 0.85	$ 0.53	$ (2.76)	$ 1.40	$ (0.84)	$ 0.22	$ 0.61	$ 1.85	$ 0.01	$ 1.72	$ 6.87
Diluted earnings per common share (in usd per share)	$ 0.83	$ 0.52	$ (2.76)	$ 1.38	$ (0.84)	$ 0.21	$ 0.58	$ 1.67	$ 0.01	$ 1.66	$ 6.16