Post (POST) 10-K 17 Nov 23 2023 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Sep. 30, 2023	Nov. 13, 2023	Mar. 31, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2023
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			$ 4,743,630,588
Entity Common Stock, Shares Outstanding (in shares)		60,354,354
Documents Incorporated by Reference	Certain portions of the registrant’s definitive proxy statement for its 2024 annual meeting of shareholders, to be filed with the Securities and Exchange Commission within 120 days after September 30, 2023, 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	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Financial Statement Error Correction [Flag]	false

Audit Information

Audit Information	12 Months Ended
	Sep. 30, 2023
Auditor [Abstract]
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Net Sales	$ 6,991	$ 5,851.2	$ 4,980.7
Cost of goods sold	5,109.3	4,383.7	3,552.6
Gross Profit	1,881.7	1,467.5	1,428.1
Selling, general and administrative expenses	1,078.4	904.7	807
Amortization of intangible assets	160.7	146	143.2
Impairment of goodwill	42.2	0	0
Other operating expense (income), net	1.5	1.2	(9.8)
Operating Profit	598.9	415.6	487.7
Interest expense, net	279.1	317.8	332.6
(Gain) loss on extinguishment of debt, net	(40.5)	(72.6)	93.2
Income on swaps, net	(39.9)	(268)	(122.8)
Gain on investment in BellRing	(5.1)	(437.1)	0
Other income, net	(7.6)	(19.8)	(29.3)
Earnings before Income Taxes and Equity Method Loss	412.9	895.3	214
Income tax expense	99.7	85.7	58.2
Equity method loss, net of tax	0.3	67.1	43.9
Net Earnings from Continuing Operations, Including Noncontrolling Interests	312.9	742.5	111.9
Less: Net earnings attributable to noncontrolling interests from continuing operations	11.6	7.5	7
Net Earnings from Continuing Operations	301.3	735	104.9
Net earnings from discontinued operations, net of tax and noncontrolling interest	0	21.6	61.8
Net Earnings	$ 301.3	$ 756.6	$ 166.7
Earnings per Common share:
Earnings (Loss) from Continuing Operations, Per Basic Share	$ 5.21	$ 12.07	$ 1.46
Earnings (Loss) from Continuing Operations, Per Diluted Share	4.82	11.75	1.44
Discontinued Operation, Earnings (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	0	0.35	0.96
Discontinued Operation, Earnings (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	0	0.34	0.94
Basic earnings per common share (in usd per share)	5.21	12.42	2.42
Diluted earnings per common share (in usd per share)	$ 4.82	$ 12.09	$ 2.38
Weighted-Average Common Shares Outstanding:
Weighted-average shares for basic earnings per share	60	60.9	64.2
Weighted-average shares for diluted earnings per share	67	62.7	65.3

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net Earnings	$ 301.3	$ 756.6	$ 166.7
Net earnings attributable to noncontrolling interests from continuing operations	11.6	7.5	7
Net earnings attributable to noncontrolling interest from discontinued operations	0	11.8	33
Net Earnings Including Noncontrolling Interests	312.9	775.9	206.7
Pension and postretirement benefits adjustments:
Unrealized pension and postretirement benefit obligations	3.4	(24)	(8.1)
Reclassifications to net earnings	(4.8)	(1.9)	(0.6)
Hedging adjustments:
Reclassifications to net earnings	0	7.1	2.3
Foreign currency translation adjustments:
Unrealized foreign currency translation adjustments	126.4	(293.9)	77.4
Tax benefit (expense) on pension and postretirement benefits adjustments:
Unrealized pension and postretirement benefit obligations	(0.3)	6.7	1.9
Reclassifications to net earnings	1.1	0.4	0.2
Tax benefit (expense) on hedging adjustments:
Reclassifications to net earnings	0	(1.8)	(0.6)
Total Other Comprehensive Income (Loss) Including Noncontrolling Interests	125.8	(307.4)	72.5
Less: Comprehensive income attributable to noncontrolling interests	9.6	20	40.3
Total Comprehensive Income	$ 429.1	$ 448.5	$ 238.9

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Current Assets
Cash and cash equivalents	$ 93.3	$ 586.5
Restricted cash	23.9	3.6
Receivables, net	512.4	544.2
Inventories	789.9	549.1
Investment in BellRing	0	94.8
Investments held in trust	0	346.8
Prepaid expenses and other current assets	59	98.4
Total Current Assets	1,478.5	2,223.4
Property, net	2,021.4	1,751.9
Goodwill	4,574.4	4,349.6
Other intangible assets, net	3,212.4	2,712.2
Other assets	360	270.9
Total Assets	11,646.7	11,308
Current Liabilities
Current portion of long-term debt	1.1	1.1
Accounts payable	368.8	452.7
Other current liabilities	435.4	370
Total Current Liabilities	805.3	823.8
Long-term debt	6,039	5,956.6
Deferred income taxes	674.4	688.4
Other liabilities	276.7	266.9
Total Liabilities	7,795.4	7,735.7
Commitments and Contingencies
Redeemable noncontrolling interest	0	306.6
Shareholders’ Equity
Preferred stock, $0.01 par value, 50.0 shares authorized; zero shares outstanding in each year	0	0
Common stock, $0.01 par value, 300.0 shares authorized; 60.4 and 58.7 shares outstanding, respectively	0.9	0.9
Additional paid-in capital	5,288.1	4,748.2
Retained earnings	1,416.5	1,109
Accumulated other comprehensive loss	(135.1)	(262.9)
Treasury stock, at cost, 31.3 and 26.9 shares, respectively	(2,728.3)	(2,341.2)
Total Shareholders’ Equity Excluding Noncontrolling Interests	3,842.1	3,254
Noncontrolling interests	9.2	11.7
Total Shareholders’ Equity	3,851.3	3,265.7
Total Liabilities and Shareholders’ Equity	$ 11,646.7	$ 11,308

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheet (Parentheticals) - $ / shares shares in Millions	Sep. 30, 2023	Sep. 30, 2022
Preferred Stock
Par value of preferred stock	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	50	50
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, Outstanding	60.4	58.7
Treasury Stock
Treasury Stock, Shares	31.3	26.9

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Cash Flows from Operating Activities:
Net earnings from continuing operations, including noncontrolling interests	$ 312.9	$ 742.5	$ 111.9
Adjustments to reconcile net earnings including noncontrolling interest to net cash provided by operating activities:
Depreciation and amortization	407.1	380.2	366.5
(Gain) loss on extinguishment of debt, net	(40.5)	(72.6)	93.2
Impairment of goodwill	42.2	0	0
Unrealized gain on interest rate swaps, foreign exchange contracts and warrant liabilities, net	(44.3)	(296.2)	(170.5)
Gain on investment in BellRing	(5.1)	(437.1)	0
Non-cash stock-based compensation expense	77.2	65.8	48.7
Equity method loss, net of tax	0.3	67.1	43.9
Deferred income taxes	(22.9)	(9.7)	68.2
Non-cash gain on write-off of deferred underwriting commissions	10.7	0	0
Other, net	24.6	0.9	(8.8)
Other changes in operating assets and liabilities, net of business acquisitions, divestitures and held for sale assets and liabilities:
Decrease (increase) in receivables, net	30.6	(102)	(117.1)
(Increase) decrease in inventories	(31.9)	(86.8)	22.1
Decrease (increase) in prepaid expenses and other current assets	50.2	0.3	(68.4)
(Increase) decrease in other assets	(17)	28.8	5.9
(Decrease) increase in accounts payable and other current liabilities	(29.9)	106.4	(48.7)
Increase (decrease) in non-current liabilities	7.5	(3.4)	15.2
Net Cash Provided by Operating Activities - continuing operations	750.3	384.2	362.1
Net Cash (Used In) Provided by Operating Activities - discontinued operations	0	(1.6)	226.1
Net Cash Provided by Operating Activities	750.3	382.6	588.2
Cash Flows from Investing Activities
Business acquisitions, net of cash acquired	(715.2)	(24.8)	(290.3)
Return of subsidiary investments held in trust account	345	0	0
Additions to property	(303)	(255.3)	(190.9)
Proceeds from sale of property and assets held for sale	1.3	18	19.4
Proceeds from sale of business	4.6	50.5	0
Sale of equity securities	0	0	34.2
Investments in partnerships	(1.7)	(9)	(22.1)
Investment of subsidiary initial public offering proceeds into trust account	0	0	(345)
Other, net	(0.3)	0.4	2.7
Net Cash Used in Investing Activities - continuing operations	(669.3)	(220.2)	(792)
Net Cash Used in Investing Activities - discontinued operations	0	(0.8)	(1.6)
Net Cash Used in Investing Activities	(669.3)	(221)	(793.6)
Cash Flows from Financing Activities
Proceeds from issuance of debt	530	2,365	1,800
Repayments of debt, net of discounts	(306.9)	(1,563.3)	(1,698.3)
Purchases of treasury stock	(387.1)	(443)	(397.1)
Proceeds from subsidiary initial public offering	0	0	305
Premium from issuance of debt	0	17.5	0
Payments of debt issuance costs, deferred financing fees and tender fees	(3.1)	(26.4)	(16.8)
Payments of debt premiums	0	(24.1)	(74.3)
Redemption of Post Holdings Partnering Corporation Series A common stock	(312.5)	0	0
Financing portion of cash paid for rate-lock interest rate swaps	(43.5)	0	0
Cash received from share repurchase contracts	0	0	47.5
Distributions (to) from BellRing Brands, Inc., net	0	(547.2)	24.6
Other, net	(32.6)	(15.7)	(37.2)
Net Cash Used in Financing Activities - continuing operations	(555.7)	(237.2)	(46.6)
Net Cash Used in Financing Activities - discontinued operations	0	(149.5)	(120.9)
Net Cash Used in Financing Activities	(555.7)	(386.7)	(167.5)
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	1.8	(9)	3.7
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(472.9)	(234.1)	(369.2)
Cash, Cash Equivalents and Restricted Cash, Beginning of Year	590.1	671.6	1,144.7
Cash, Cash Equivalents and Restricted Cash from discontinued operations, Beginning of Year	0	152.6	48.7
Cash, Cash Equivalents and Restricted Cash from discontinued operations, End of Year	0	0	152.6
Cash, Cash Equivalents and Restricted Cash, End of Year	$ 117.2	$ 590.1	$ 671.6

Consolidated Statement of Share

Consolidated Statement of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Preferred Stock	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	Noncontrolling Interest	Stockholders Equity, excluding Mezzanine Equity	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares			0
Common Stock, Shares, Outstanding		66.4
Balance at beginning of period at Sep. 30, 2020				$ 0	$ 0.8	$ 4,182.9	$ 208.6	$ (4.3)	$ 70.3	$ (95.3)	$ (25.5)	$ 2,829	$ (1,508.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Earnings	$ 166.7						166.7					166.7
Post Holdings Partnering Corporation deemed dividend							(28)					(28)
Activity under stock and deferred compensation plans					0.1	(28.1)					(0.8)	(28.8)
Activity under stock and deferred compensation plans (shares)		0.7	0
Non-cash stock-based compensation expense						51.2					4.6	55.8
Purchases of treasury stock (shares)		(4)
Purchases of treasury stock		$ (393.7)				0						(393.7)	(393.7)
Net earnings attributable to noncontrolling interest	7										34.2	34.2
Cash paid for share repurchase contracts						47.5						47.5
Distribution to noncontrolling interest	(1)						0				(1)
Net change in retirement benefits, net of tax								(6.6)				(6.6)
Net change in hedges, net of tax									1.1		0.6	1.7
Foreign currency translation adjustments										77.7	(0.3)	77.4
Balance at the end of period at Sep. 30, 2021				0	0.9	4,253.5	347.3	(10.9)	71.4	(17.6)	11.8	2,754.2	(1,902.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares			0
Common Stock, Shares, Outstanding		63.1
Net Earnings	756.6						756.6					756.6
Post Holdings Partnering Corporation deemed dividend							5.1					5.1
Activity under stock and deferred compensation plans					0	(14.3)					(0.9)	(15.2)
Activity under stock and deferred compensation plans (shares)		0.5	0
Non-cash stock-based compensation expense						66.5					2.9	69.4
Purchases of treasury stock (shares)		(4.9)
Purchases of treasury stock		$ (439)				0					(18.1)	(457.1)	(439)
Net earnings attributable to noncontrolling interest	7.5										12.6	12.6
Net change in retirement benefits, net of tax								(18.8)				(18.8)
Net change in hedges, net of tax									3.4		1.9	5.3
Foreign currency translation adjustments										(292.7)	(1.2)	(293.9)
BellRing Spin-Off						442.5				2.3	2.7	447.5
Balance at the end of period at Sep. 30, 2022	3,265.7			0	0.9	4,748.2	1,109	(29.7)	74.8	(308)	11.7	3,265.7	(2,341.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares			0
Common Stock, Shares, Outstanding		58.7
Net Earnings	301.3						301.3					301.3
Post Holdings Partnering Corporation deemed dividend							6.2					6.2
Activity under stock and deferred compensation plans		$ 0				(29.6)					0	(29.6)
Activity under stock and deferred compensation plans (shares)		0	0
Non-cash stock-based compensation expense						77.2					0	77.2
Issuance of common stock, shares		6.1
Issuance of common stock						492.3						492.3
Purchases of treasury stock (shares)		(4.4)	0
Purchases of treasury stock		$ (387.1)									0	(387.1)	(387.1)
Net earnings attributable to noncontrolling interest	11.6										(0.5)	(0.5)
Net change in retirement benefits, net of tax								(0.6)				(0.6)
Foreign currency translation adjustments										128.4	(2)	126.4
Balance at the end of period at Sep. 30, 2023	$ 3,851.3			$ 0	$ 0.9	$ 5,288.1	$ 1,416.5	$ (30.3)	$ 74.8	$ (179.6)	$ 9.2	$ 3,851.3	$ (2,728.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Shares			0
Common Stock, Shares, Outstanding		60.4

Background

Background	12 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background	BACKGROUND Post is a consumer packaged goods holding company operating in the center-of-the-store, refrigerated, foodservice and food ingredient categories. 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, 2023, Post operates in four reportable segments: Post Consumer Brands, Weetabix, Foodservice and Refrigerated Retail. The Post Consumer Brands segment includes North American ready-to-eat (“RTE”) cereal, pet food and nut butters products; the Weetabix segment includes primarily United Kingdom (“U.K.”) RTE cereal, muesli and protein-based shake products; the Foodservice segment includes primarily egg and potato products; and the Refrigerated Retail segment includes primarily side dish, egg, cheese and sausage products. 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 subsidiaries. On March 10, 2022, the Company completed its distribution of 80.1% of its ownership interest in BellRing Brands, Inc. (formerly known as BellRing Distribution, LLC) (“BellRing”) to Post’s shareholders (the “BellRing Distribution,” and such transaction, as well as the BellRing Contribution, the BellRing Merger (as such terms are defined in Note 4), the Debt-for-Debt Exchange (as such term is defined in Note 16) and the related transactions described in Note 4, the “BellRing Spin-off”). The BellRing Spin-off represented a strategic shift that had a major effect on the Company’s operations and consolidated financial results. Accordingly, the historical results of BellRing Intermediate Holdings, Inc. (formerly known as BellRing Brands, Inc.) (“Old BellRing”) and BellRing Distribution, LLC prior to the BellRing Spin-off have been presented as discontinued operations in the Company’s Consolidated Statements of Operations and Consolidated Statements of Cash Flows. The Notes to Consolidated Financial Statements reflect continuing operations only, unless otherwise indicated. See Note 4 for additional information regarding the BellRing Spin-off and discontinued operations. The Company completed its acquisitions of the Egg Beaters liquid egg brand (“Egg Beaters”) and the Peter Pan nut butter brand (“Peter Pan”) on May 27, 2021 and January 25, 2021, respectively. The year-end close date for both Egg Beaters and Peter Pan was September 26, 2021. As the amounts associated with the additional four days were immaterial, results of these entities were not adjusted to conform with Post’s fiscal calendar in fiscal 2021. Certain reclassifications have been made to previously reported financial information to conform to the Company’s current period presentation.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Sep. 30, 2023
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 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, allowance for trade promotions, business combinations, pension and benefit plan assumptions, valuation assumptions of goodwill and other intangible assets and income taxes. Actual results could differ from those estimates. Business Combinations — The Company uses the acquisition method of accounting for acquired businesses. Under the acquisition method, the Company’s financial statements reflect the operations of an acquired business starting from the date of acquisition. The assets acquired and liabilities assumed are recorded at their respective estimated fair values at the date of the acquisition. Useful lives of identified tangible and intangible assets are determined based on the expected time period in which the cash flows of the related assets are expected to be realized. 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 acquired over the purchase price is recorded as a gain on bargain purchase. The Company utilizes various valuation methodologies (and depending on the size and complexity of an acquisition, assistance from third-party specialists) to estimate the fair value of assets acquired and liabilities assumed based on the nature of the underlying asset or liability. These methodologies include but are not limited to utilizing replacement cost, comparative sales and market- and income-based approaches. The income approach utilizes significant unobservable inputs, including revenue growth rates, discount rates, attrition rates and royalty rates. These fair value measurements fall within Level 3 of the fair value hierarchy as described in Note 14. During the measurement period, up to twelve months from the date of acquisition, subsequent changes may be made to adjust the preliminary amounts recognized at the acquisition date to their subsequently determined acquisition-date fair values. Cash Equivalents — Cash equivalents include all highly liquid investments with original maturities of less than three months. Restricted Cash — Restricted cash includes cash deposits which serve as collateral for certain commodity and energy hedging contracts as well as the Company’s high deductible workers’ compensation insurance program. Receivables — Receivables are reported net of appropriate allowances for credit losses, cash discounts and other amounts which the Company does not ultimately expect to collect. To calculate an allowance for credit losses, the Company estimates uncollectible amounts based on a review of past due balances, historical loss information and expectations regarding potential future losses. 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. As of September 30, 2023 and 2022, the Company did not have off-balance sheet credit exposure related to its customers. The Weetabix segment sells certain receivables to a third-party institution without recourse. Receivables sold during the years ended September 30, 2023 and 2022 were $92.5 and $111.7, respectively. See Note 6 for information regarding the Company’s monthly settlement of receivables and payables with a third party in connection with its fiscal 2023 acquisition. Inventories — Inventories, other than flocks, are generally valued at the lower of cost (determined on a first-in, first-out basis) or net realizable value. Reported amounts have been reduced by an allowance for excess and 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 and related charges principally consist of one-time termination benefits, severance, contract termination benefits, accelerated stock compensation and other employee separation costs. 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. 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 30 years for machinery and equipment; 1 to 35 years for buildings, building improvements and leasehold improvements; and 1 to 7 years for software. Total depreciation expense was $245.3, $232.9 and $222.2 in fiscal 2023, 2022 and 2021, respectively. Any gains and losses incurred on the sale or disposal of assets are included in “Other operating expense (income), net” in the Consolidated Statements of Operations. Ordinary repair and maintenance costs are accounted for under the direct expensing method. Property consisted of: September 30, 2023 2022 Land and land improvements $ 109.9 $ 92.2 Buildings and leasehold improvements 1,042.9 932.7 Machinery and equipment 2,312.2 1,951.1 Software 113.3 110.6 Construction in progress 191.1 182.7 3,769.4 3,269.3 Accumulated depreciation (1,748.0) (1,517.4) $ 2,021.4 $ 1,751.9 Goodwill — Goodwill is calculated as the excess of the purchase price of acquired businesses over the fair market value of their identifiable net assets and represents the value the Company expects to achieve through the implementation of operational synergies, the expansion of the business into new or growing segments of the industry and the addition of new employees. The Company conducts a goodwill impairment 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 assessment performed may be either qualitative or quantitative; however, 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 2023, 2022 and 2021, the Company performed a quantitative impairment test for all reporting units. The Company has six reporting units, which have been identified at either the operating segment level, or in the case of certain reporting units, at a level below the operating segment. The estimated fair value of each reporting unit 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 for comparable peers. These fair value measurements fall within Level 3 of the fair value hierarchy as described in Note 14. See Note 8 for additional information on goodwill and the annual goodwill impairment assessments for the years ended September 30, 2023, 2022 and 2021. Other Intangible Assets — Other intangible assets consist primarily of customer relationships, trademarks, brands and licensing agreements 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 $160.7, $146.0 and $143.2 in fiscal 2023, 2022 and 2021, respectively. For the definite-lived intangible assets recorded as of September 30, 2023, amortization expense of $179.9, $178.7, $178.7, $178.7 and $173.5 is expected for fiscal 2024, 2025, 2026, 2027 and 2028, respectively. Other intangible assets consisted of: September 30, 2023 September 30, 2022 Carrying Accum. Net Carrying Accum. Net Subject to amortization: Customer relationships $ 2,535.5 $ (940.7) $ 1,594.8 $ 2,129.7 $ (816.4) $ 1,313.3 Trademarks, brands and licensing agreements 885.8 (301.3) 584.5 647.7 (260.4) 387.3 3,421.3 (1,242.0) 2,179.3 2,777.4 (1,076.8) 1,700.6 Not subject to amortization: Trademarks and brands 1,033.1 — 1,033.1 1,011.6 — 1,011.6 $ 4,454.4 $ (1,242.0) $ 3,212.4 $ 3,789.0 $ (1,076.8) $ 2,712.2 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 and right-of-use (“ROU”) assets. Trademarks and brands 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 or brand may be impaired. The trademark and brand impairment test performed may either be qualitative or quantitative; however, if adverse qualitative trends are identified that could negatively impact the fair value of the trademark or brand, a quantitative impairment test is performed. In fiscal 2023, 2022 and 2021, the Company performed a quantitative impairment test. The quantitative trademark and brand impairment tests require the Company to compare the calculated fair value of the trademark or brand to its carrying value. If the carrying value of the intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. The fair value is determined using an income-based approach, 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 fiscal 2023, 2022 and 2021, the Company performed a quantitative impairment test for all indefinite-lived intangible assets and concluded for each year there were no impairments. The estimated fair value of all indefinite-lived trademarks exceeded book value by 11% or greater, 23% or greater and 22% or greater at September 30, 2023, 2022 and 2021, respectively . These fair value measurements fall within Level 3 of the fair value hierarchy as described in Note 14. In addition, definite-lived assets (groups) are tested for recoverability when events or changes in circumstances indicate that the carrying value of an asset (group) may not be recoverable or the estimated useful life is no longer appropriate. The Company groups assets at the lowest level for which cash flows are separately identifiable. In general, an asset (group) is deemed impaired and written down to its fair value if the estimated related undiscounted future cash flows are less than its carrying amount. There were no impairments recorded on the Company’s definite-lived assets (groups) in fiscal 2023, 2022 or 2021. Software Implementation Costs — For hosting arrangements that are service contracts, the Company capitalizes certain implementation costs incurred during the development stage of the related project . Capitalized software implementation costs are expensed on a straight-line basis over the term of the hosting service arrangement, beginning when the software is ready for its intended use. Total capitalized software implementation costs for hosting service arrangements are recorded in “Prepaid expenses and other current assets” and “Other assets” on the Consolidated Balance Sheets and were $20.4 and $7.6 as of September 30, 2023 and 2022, respectively. There were no material capitalized software implementation costs expensed in fiscal 2023, 2022 or 2021. Deferred Compensation Investments — The Company funds a portion of its deferred compensation liability by investing in certain mutual funds in substantially 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 are stated at fair value in “Prepaid expenses and other current assets” and “Other assets” on the Consolidated Balance Sheets (see Note 14). Both realized and unrealized gains and losses on these assets are generally 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 purchases of raw materials and supplies, interest rate risks 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 may 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. Gains and losses on derivatives designated as cash flow hedges are recorded in other comprehensive income or loss (“OCI”) and are reclassified to the Consolidated Statements of Operations in conjunction with the recognition of the underlying hedged item. If a derivative is designated as a hedge of a net investment in a foreign operation, its changes in fair value are recorded in OCI and subsequently recognized in earnings when the foreign operation is liquidated. Changes in the fair value of derivatives that are not designated for hedge accounting are recognized immediately in the Consolidated Statements of Operations. The Company does not have any derivatives currently designated as hedging instruments under Accounting Standards Codification (“ASC”) Topic 815, “Derivatives and Hedging.” Cash flows associated with all derivatives are reported as cash flows from operating activities in the Consolidated Statements of Cash Flows, unless the derivative contains an other-than-insignificant financing element, in which case its cash flows are reported as cash flows from financing activities. Leases — The Company leases office space, certain warehouses and equipment primarily through operating lease agreements. The Company has no material finance lease agreements. 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. For lease arrangements that 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 Sheets. 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 do not have a material impact on the Company’s financial statements. Revenue — 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. Cost of Goods Sold — Cost of goods sold includes, among other things, inbound and outbound freight costs (including for the Company-owned fleets) 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 $263.2, $204.0 and $167.7 in fiscal 2023, 2022 and 2021, respectively. Advertising — Advertising costs are expensed as incurred except for costs of producing media advertising, such as television commercials or magazine or 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 $1.4 as of September 30, 2023 and 2022, 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 the equity or liability award. For liability awards, the fair market value is remeasured at each quarterly reporting period. The cost for equity and liability awards is recognized ratably 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. Income Taxes — Income tax expense 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 established against the related deferred tax assets to the extent that it is more likely than not that the future benefits will not be realized. Reserves are recorded for estimated exposures associated with the Company’s tax filing positions, which are subject to periodic audits by governmental taxing authorities. Interest incurred due to an underpayment of income taxes is classified as income tax expense. The Company considers the undistributed earnings of its foreign subsidiaries to be permanently invested, so no United States (“U.S.”) taxes have been recorded in relation to the Company’s investment in its foreign subsidiaries. Earnings per Share — The Company has presented basic and diluted earnings per share for both continuing and discontinued operations. Basic earnings per share is based on the average number of shares of common stock outstanding during the year. 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 and restricted stock units using the “treasury stock” method and convertible senior notes using the “if-converted” method. Remeasurements to the redemption value of the redeemable noncontrolling interest (“NCI”) (see Note 5) were recognized as a deemed dividend. The Company made an election to treat the portion of the deemed dividend that exceeded fair value as an adjustment to income available to common shareholders for basic and diluted earnings from continuing operations per share. In

Recently Issued and Adopted Acc

Recently Issued and Adopted Accounting Standards	12 Months Ended
	Sep. 30, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
New Accounting Pronouncements and Changes in Accounting Principles	RECENTLY ISSUED AND ADOPTED ACCOUNTING STANDARDSThe Company has considered all new accounting pronouncements and has concluded there are no new pronouncements that had or will have a material impact on the Company’s results of operations, comprehensive income, financial condition, cash flows, shareholders’ equity or related disclosures based on current information.

Discontinued Operations and Dis

Discontinued Operations and Disposal Groups	12 Months Ended
	Sep. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations, Disclosure	BELLRING SPIN-OFF AND DISCONTINUED OPERATIONS BellRing Spin-off On March 9, 2022, pursuant to the Transaction Agreement and Plan of Merger, dated as of October 26, 2021 (as amended by Amendment No. 1 to the Transaction Agreement and Plan of Merger, dated as of February 28, 2022, the “Spin-off Agreement”), by and among Post, Old BellRing, BellRing and BellRing Merger Sub Corporation, a wholly-owned subsidiary of BellRing (“BellRing Merger Sub”), Post contributed its share of Old BellRing Class B common stock, $0.01 par value per share, all of its BellRing Brands, LLC non-voting membership units and $550.4 of cash to BellRing in exchange for certain limited liability company interests of BellRing and the right to receive $840.0 in aggregate principal amount of BellRing’s 7.00% senior notes maturing in 2030 (the “BellRing Notes,” and such transactions, collectively, the “BellRing Contribution”). On March 10, 2022, BellRing converted into a Delaware corporation and changed its name to “BellRing Brands, Inc.”, and Post consummated the BellRing Distribution, distributing an aggregate of 78.1 million, or 80.1%, of its shares of BellRing common stock, $0.01 par value per share (“BellRing Common Stock”), to Post shareholders of record as of the close of business, Central Time, on February 25, 2022 (the “Record Date”) in a pro-rata distribution. Post shareholders received 1.267788 shares of BellRing Common Stock for every one share of Post common stock held as of the Record Date. No fractional shares of BellRing Common Stock were issued, and instead, cash in lieu of any fractional shares was paid to Post shareholders. Upon completion of the BellRing Distribution, BellRing Merger Sub merged with and into Old BellRing (the “BellRing Merger”), with Old BellRing continuing as the surviving corporation and becoming a wholly-owned subsidiary of BellRing. The Company’s equity interest in BellRing subsequent to the BellRing Spin-off (its “Investment in BellRing”) was 14.2% immediately following the BellRing Spin-off. As a result of the BellRing Spin-off, the dual class voting structure in the BellRing business was eliminated. The BellRing Distribution was structured in a manner intended to qualify as a tax-free distribution to Post shareholders for U.S. federal income tax purposes, except to the extent of any cash received in lieu of fractional shares of BellRing Common Stock. The Company incurred separation-related expenses related to the BellRing Spin-off and subsequent divestment of its Investment in BellRing (see Note 5) of $0.1, $29.9 and $1.6 during the years ended September 30, 2023, 2022 and 2021, respectively, which were included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. These expenses generally included third-party costs for advisory services, fees charged by other service providers and government filing fees. On March 17, 2022, the Company utilized proceeds received in connection with the BellRing Spin-off to redeem a portion of Post’s existing 5.75% senior notes (see Note 16). The following is a summary of BellRing’s net assets as of March 10, 2022. Total Assets $ 633.0 Less: Total Liabilities 1,064.6 BellRing Net Assets $ (431.6) As a result of the BellRing Spin-off, the Company recorded a $442.5 adjustment to additional paid-in capital, which included BellRing net assets of $(431.6). The BellRing Spin-off also resulted in a reduction of accumulated OCI associated with BellRing’s foreign currency translation adjustments. The total adjustment to accumulated OCI was $2.3. The Company’s Investment in BellRing immediately following the BellRing Spin-off did not represent a controlling interest in BellRing. As such, the Company’s remaining proportionate share of BellRing’s net assets was recorded at a zero carrying value on March 10, 2022, as the BellRing net assets were negative. See Note 14 for additional information regarding the Company’s subsequent remeasurement of its Investment in BellRing to fair value for the periods subsequent to the BellRing Spin-off. Discontinued Operations The BellRing Spin-off represented a strategic shift that had a major effect on the Company’s operations and consolidated financial results. Accordingly, the historical results of Old BellRing and BellRing Distribution, LLC prior to the BellRing Spin-off have been presented as discontinued operations in the Company’s Consolidated Statements of Operations and Consolidated Statements of Cash Flows. The following table presents the components of net earnings from discontinued operations. The year ended September 30, 2022 represents the period ending March 10, 2022, the completion date of the BellRing Spin-off. Year Ended September 30, 2022 2021 Net Sales $ 541.9 $ 1,246.0 Cost of goods sold 390.3 859.8 Gross Profit 151.6 386.2 Selling, general and administrative expenses 68.5 167.1 Amortization of intangible assets 8.7 51.2 Other operating income, net — (0.1) Operating Profit 74.4 168.0 Interest expense, net 13.1 43.2 Loss on extinguishment and refinancing of debt, net 17.6 1.6 Earnings from Discontinued Operations before Income Taxes 43.7 123.2 Income tax expense 10.3 28.4 Net Earnings from Discontinued Operations, Including Noncontrolling Interest 33.4 94.8 Less: Net earnings attributable to noncontrolling interest from discontinued operations 11.8 33.0 Net Earnings from Discontinued Operations, net of tax and noncontrolling interest $ 21.6 $ 61.8

Noncontrolling Interests, Equit

Noncontrolling Interests, Equity Interests and Related Party Transactions	12 Months Ended
	Sep. 30, 2023
Equity Method Investments and Joint Ventures [Abstract]
Noncontrolling Interests, Equity Interests and Related Party Transactions	NONCONTROLLING INTERESTS, EQUITY INTERESTS AND RELATED PARTY TRANSACTIONS
Equity Method Investments and Joint Ventures Disclosure - PHPC	Post Holdings Partnering Corporation In May and June 2021, the Company and Post Holdings Partnering Corporation (“PHPC”), a special purpose acquisition company, consummated the initial public offering of 34.5 million units of PHPC (the “PHPC Units,” and such transaction, the “PHPC IPO”), of which a wholly-owned subsidiary of the Company (“PHPC Sponsor”) purchased 4.0 million PHPC Units. Each PHPC Unit consisted of one share of Series A common stock of PHPC (“PHPC Series A Common Stock”) and one-third of one redeemable warrant to purchase one share of PHPC Series A Common Stock at an exercise price of $11.50 per share (the “PHPC Warrants”). The PHPC Units were sold at a price of $10.00 per PHPC Unit, generating gross proceeds to PHPC of $345.0. The PHPC Units, PHPC Series A Common Stock and PHPC Warrants each traded on the New York Stock Exchange (the “NYSE”) under the ticker symbols “PSPC.U”, “PSPC” and “PSPC WS”, respectively. Under the terms of the PHPC IPO, PHPC was required to consummate a partnering transaction by May 28, 2023, which could have been extended to August 28, 2023 in certain circumstances (the “Combination Period”). Substantially concurrently with the closing of the PHPC IPO, PHPC completed the private sale of 1.1 million units of PHPC (the “PHPC Private Placement Units”), at a purchase price of $10.00 per PHPC Private Placement Unit, to PHPC Sponsor, generating proceeds to PHPC of $10.9 (the “PHPC Private Placement”). The PHPC Private Placement Units sold in the PHPC Private Placement were identical to the PHPC Units sold in the PHPC IPO, except that, with respect to the warrants underlying the PHPC Private Placement Units (the “PHPC Private Placement Warrants”) that were held by PHPC Sponsor or its permitted transferees, such PHPC Private Placement Warrants (i) could have been exercised for cash or on a cashless basis, (ii) were not subject to being called for redemption (except in certain circumstances if the PHPC Warrants were called for redemption and a certain price per share of PHPC Series A Common Stock threshold was met) and (iii) subject to certain limited exceptions, would have been subject to transfer restrictions until 30 days following the consummation of PHPC’s partnering transaction. If the PHPC Private Placement Warrants were held by holders other than PHPC Sponsor or its permitted transferees, the PHPC Private Placement Warrants would have been redeemable by PHPC in all redemption scenarios and exercisable by holders on the same basis as the PHPC Warrants. In addition, the Company, through PHPC Sponsor’s ownership of 8.6 million shares of Series F common stock of PHPC (the “PHPC Series F Common Stock”), had certain governance rights in PHPC relating to the election of PHPC directors and voting rights on amendments to PHPC’s amended and restated certificate of incorporation. In connection with the completion of the PHPC IPO, PHPC also entered into a forward purchase agreement with PHPC Sponsor (the “Forward Purchase Agreement”), which provided for the purchase by PHPC Sponsor, at the election of PHPC, of up to 10.0 million units of PHPC (the “PHPC Forward Purchase Units”), subject to the terms and conditions of the Forward Purchase Agreement, with each PHPC Forward Purchase Unit consisting of one share of PHPC’s Series B common stock and one-third of one warrant to purchase one share of PHPC Series A Common Stock, for a purchase price of $10.00 per PHPC Forward Purchase Unit, in an aggregate amount of up to $100.0 in a private placement to occur concurrently with the closing of PHPC’s partnering transaction. In determining the accounting treatment of the Company’s equity interest in PHPC, management concluded that PHPC was a variable interest entity (“VIE”) as defined by ASC Topic 810, “Consolidation.” A VIE is an entity in which equity investors at risk lack the characteristics of a controlling financial interest. VIEs are consolidated by the primary beneficiary, the party who has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance, as well as the obligation to absorb losses of the entity or the right to receive benefits from the VIE that could potentially be significant to the VIE. PHPC Sponsor was the primary beneficiary of PHPC as it had, through its equity interest, the right to receive benefits or the obligation to absorb losses from PHPC, as well as the power to direct a majority of the activities that significantly impacted PHPC’s economic performance, including partnering transaction target identification. As such, PHPC was fully consolidated into the Company’s financial statements until the time of its dissolution, as discussed below. Pr oceeds of $345.0 were deposited in a trust account established for the benefit of PHPC’s public stockholders, which consisted of certain proceeds from the PHPC IPO and certain proceeds from the PHPC Private Placement, net of underwriters’ discounts and commissions and other costs and expenses. A minimum balance of $345.0, which represented the number of PHPC Units sold at the offering price of $10.00 per PHPC Unit , was required by the underwriting agreement to be maintained in the trust account. These pr oceeds were invested only in U.S. treasury securities. At September 30, 2022, there was $346.8 held in the trust account, which was included in “Investments held in trust” on the Consolidated Balance Sheets. The public stockholders’ ownership of PHPC equity represented a NCI to the Company, which was classified outside of permanent shareholders’ equity as the PHPC Series A Common Stock was redeemable at the option of the public stockholders in certain circumstances. The carrying amount of the redeemable NCI was equal to the greater of (i) the initial carrying amount, increased or decreased for the redeemable NCI’s share of PHPC’s net earnings or loss, OCI and distributions or (ii) the redemption value. The redemption value represented the amount the public stockholders of PHPC Series A Common Stock would be entitled in certain circumstances to redeem their shares of PHPC Series A Common Stock for, which was a pro-rata portion of the amount in the trust account at $10.00 per share of PHPC Series A Common Stock held, plus any pro-rata interest earned on the funds held in the trust account (which interest was net of taxes payable, and less up to $0.1 of interest to pay dissolution expenses). As of September 30, 2022, the carrying amount of the redeemable NCI was recorded at its redemption value of $306.6 on the Consolidated Balance Sheets. Remeasurements to the redemption value of the redeemable NCI were recognized as a deemed dividend and were recorded to “Retained earnings” on the Consolidated Balance Sheets. In connection with the PHPC IPO, PHPC incurred offering costs of $17.9, of which $16.9 was recorded to the redeemable NCI and $1.0 was reported in “Selling, general and administrative expenses” in the Consolidated Statements of Operations for the year ended September 30, 2021. Of the $17.9 offering costs incurred, $10.7 were deferred underwriting commissions that would have become payable to the underwriters solely in the event that PHPC completed a partnering transaction and were included in “Other current liabilities” on the Consolidated Balance Sheets at September 30, 2022. As of September 30, 2022 and prior to the PHPC Redemption (as defined below), the Company beneficially owned 31.0% of the equity of PHPC and the net earnings and net assets of PHPC were consolidated within the Company’s financial statements. The remaining 69.0% of the consolidated net earnings and net assets of PHPC, which represented the percentage of economic interest in PHPC held by the public stockholders of PHPC through their ownership of PHPC equity, were allocated to redeemable NCI. All transactions between PHPC and PHPC Sponsor, as well as related financial statement impacts, eliminated in consolidation. On May 11, 2023, PHPC announced that it would not complete a partnering transaction within the Combination Period and that the entity would liquidate and dissolve in accordance with the terms of its amended and restated certificate of incorporation. Subsequent to the decision to liquidate and dissolve, PHPC completed certain winding-up activities, which included writing-off the deferred underwriting commissions as the underwriters agreed to waive their rights to these amounts should a partnering transaction not occur. The Company recorded a $10.7 gain in connection with this write-off, which was recorded in “Other income, net” on the Consolidated Statements of Operations during the year ended September 30, 2023. On May 28, 2023, the PHPC Warrants and the PHPC Private Placement Warrants expired worthless and the Forward Purchase Agreement terminated in accordance with its terms, as PHPC had not completed a partnering transaction before the expiration of the Combination Period. On May 30, 2023, PHPC redeemed all of the outstanding public shares of PHPC Series A Common Stock (the “PHPC Redemption”). Each share of PHPC Series A Common Stock was redeemed for approximately $10.24 per share, representing the per share price equal to the aggregate amount then on deposit in the trust account, including interest earned on the trust account not previously released to pay taxes or dissolution expenses, divided by the number of then outstanding shares of PHPC Series A Common Stock. In connection with the PHPC Redemption: • $353.4 of funds held in the trust account immediately prior to the PHPC Redemption were distributed to redeem all of the outstanding shares of PHPC Series A Common Stock, which reduced “Investments held in trust” on the Consolidated Balance Sheets to zero as of September 30, 2023. The Company received $40.9 from the PHPC Redemption related to its ownership of 4.0 million shares of PHPC Series A Common Stock; and • redeemable NCI of $312.5 immediately prior to the PHPC Redemption was reduced to zero on the Consolidated Balance Sheets as of September 30, 2023. Subsequent to the PHPC Redemption, PHPC delisted from the NYSE and dissolved in June 2023, and all classes of shares of PHPC equity were cancelled, including the PHPC Private Placement Units and the shares of the PHPC Series F Common Stock, which were surrendered by PHPC Sponsor for no consideration. PHPC Sponsor subsequently dissolved in August 2023. The following table summarizes the effects of changes in the Company’s redeemable NCI on the Company’s equity. The year ended September 30, 2021 represents the period that began May 28, 2021, the effective date of the PHPC IPO, and ended September 30, 2021. The year ended September 30, 2023 represents the period ended May 30, 2023, as the Company’s redeemable NCI was reduced to zero upon completion of the PHPC Redemption. Year Ended September 30, 2023 2022 2021 PHPC IPO offering costs $ — $ — $ (16.9) Initial valuation of PHPC Warrants — — (16.9) Net earnings attributable to redeemable NCI 12.1 6.7 5.8 Redemption value adjustment (5.9) (1.6) — PHPC deemed dividend $ 6.2 $ 5.1 $ (28.0) The following table summarizes the changes to the Company’s redeemable NCI. The period as of and for the year ended September 30, 2021 represents the period that began May 28, 2021, the effective date of the PHPC IPO, and ended September 30, 2021. The period as of and for the year ended September 30, 2023 represents the period ended May 30, 2023, as the Company’s redeemable NCI was reduced to zero upon completion of the PHPC Redemption. As of and for the Year Ended September 30, 2023 2022 2021 Balance, beginning of year $ 306.6 $ 305.0 $ — Impact of PHPC IPO (a) — — 271.2 Net earnings attributable to redeemable NCI 12.1 6.7 5.8 PHPC deemed dividend (6.2) (5.1) 28.0 Redemption of PHPC Series A Common Stock (312.5) — — Balance, end of year $ — $ 306.6 $ 305.0 (a) For the year ended September 30, 2021, the impact of the PHPC IPO included the value of PHPC Units owned by public stockholders of $305.0 less offering costs of $16.9 and the initial valuation of PHPC Warrants of $16.9.
Equity Method Investments and Joint Ventures Disclosure - 8th	8th Avenue The Company has a 60.5% common equity interest in 8th Avenue Food & Provisions, Inc. (“8th Avenue”) that is accounted for using the equity method. In determining the accounting treatment of the common equity interest, management concluded that 8th Avenue was not a VIE as defined by ASC Topic 810, 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 third parties 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. During the year ended September 30, 2022, 8th Avenue’s equity method loss attributable to Post exceeded the Company’s remaining investment in 8th Avenue. In accordance with ASC Topic 323, “Investments—Equity Method and Joint Ventures,” the Company did not recognize equity method losses in excess of its remaining investment in 8th Avenue, which was $66.6 as of September 30, 2021, and discontinued applying the equity method to the investment. As such, the Company’s investment in 8th Avenue was zero at both September 30, 2023 and 2022, and there was no equity method gain (loss) attributable to 8th Avenue recognized during the year ended September 30, 2023. The following table presents the calculation of the Company’s equity method loss attributable to 8th Avenue for the year ended September 30, 2021. Net loss attributable to 8th Avenue common shareholders $ (60.6) 60.5 % Equity method loss attributable to Post $ (36.7) Less: Amortization of basis difference, net of tax (a) 6.8 Equity method loss, net of tax $ (43.5) (a) The Company adjusted the historical basis of 8th Avenue’s assets and liabilities to fair value and recognized a basis difference of $70.3 upon the initial recording of its equity method investment in 8th Avenue. The basis difference related to property, plant and equipment and other intangible assets was initially amortized over the weighted-average useful lives of the assets. During the year ended September 30, 2022, the carrying value of the Company’s investment in 8th Avenue was reduced to zero, resulting in the termination of basis difference amortization in accordance with ASC Topic 323. The following table presents summarized financial information of 8th Avenue prior to the discontinuance of applying the equity method to the investment. Year Ended September 30, 2022 2021 Net sales $ 1,089.0 $ 900.8 Gross profit $ 159.9 $ 132.3 Net loss $ (210.9) $ (24.3) Less: Preferred stock dividend 40.4 36.3 Net loss attributable to 8th Avenue common shareholders $ (251.3) $ (60.6) The Company provides services to 8th Avenue under a master services agreement (the “MSA”), as well as certain advisory services for a fee. During the years ended September 30, 2023, 2022 and 2021, the Company recorded MSA and advisory income of $3.1, $3.2 and $3.5, respectively, which were recorded in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. During the years ended September 30, 2023, 2022 and 2021, the Company had net sales to 8th Avenue of $8.0, $8.1 and $6.7, respectively, and purchases from and royalties paid to 8th Avenue of $83.9, $102.9 and $54.1 respectively. Sales and purchases between the Company and 8th Avenue were all made at arm’s-length. The Company had current receivables and current payables with 8th Avenue of $3.9 and $13.3, respectively, at September 30, 2023, and $4.4 and $26.1, respectively, at September 30, 2022. The current receivables and current payables were included in “Receivables, net” and “Accounts payable,” respectively, on the Consolidated Balance Sheets and related to MSA fees, pass-through charges owed by 8th Avenue to the Company and related party sales and purchases. In addition, the Company has a long-term receivable and a long-term liability with 8th Avenue of $12.9 and $0.7, respectively, at September 30, 2023 and zero and $0.7, respectively, at September 30, 2022, which were included in “Other assets” and “Other liabilities,” respectively, on the Consolidated Balance Sheets and related to tax indemnifications.
Equity Method Investments and Joint Ventures Disclosure - BRBR	Investment in BellRing Immediately following the BellRing Spin-off, the Company’s Investment in BellRing represented 19.4 million shares of BellRing Common Stock, or a 14.2% equity interest in BellRing, which did not represent a controlling interest in BellRing and was accounted for as an equity security. On August 11, 2022, the Company transferred 14.8 million shares of its Investment in BellRing to repay certain outstanding debt obligations as part of the First Debt-for-Equity Exchange (as defined in Note 16). See Note 16 for additional information regarding the First Debt-for-Equity Exchange. As a result, the Company’s remaining Investment in BellRing as of September 30, 2022 represented 4.6 million shares of BellRing Common Stock, or 3.4% of the outstanding equity of BellRing. As of September 30, 2022, the Company’s Investment in BellRing was recorded at its fair value of $94.8 and was included in “Investment in BellRing” on the Consolidated Balance Sheets (see Note 14). On November 25, 2022, the Company transferred the remaining 4.6 million shares of its Investment in BellRing to repay certain outstanding debt obligations as part of the Second Debt-for-Equity Exchange (as defined in Note 16). See Note 16 for additional information regarding the Second Debt-for-Equity Exchange. The Company had no ownership of BellRing Common Stock as of September 30, 2023. The Company recognized a gain on its Investment in BellRing of $5.1 and $437.1 during the years ended September 30, 2023 and 2022, respectively, which was recorded in “Gain on investment in BellRing” in the Consolidated Statements of Operations. No deferred income taxes have been recorded with respect to the non-cash mark-to-market adjustments on the Company’s Investment in BellRing as of September 30, 2023 or 2022, as the Company fully divested its Investment in BellRing within 12 months of the BellRing Spin-off in a manner intended to qualify as tax-free for U.S. federal income tax purposes.
Equity Method Investments and Joint Ventures Disclosure - WBX	Weetabix East Africa and Alpen The Company holds a controlling equity interest in Weetabix East Africa Limited (“Weetabix East Africa”). Weetabix East Africa is a Kenyan-based company that produces RTE cereal and muesli. The Company owns 50.1% of Weetabix East Africa and holds a controlling voting and financial interest through its appointment of management and representation on Weetabix East Africa’s board of directors. Accordingly, Weetabix East Africa is fully consolidated into the Company’s financial statements and its assets and results of operations are reported in the Weetabix segment. The remaining interest in the consolidated net earnings and net assets of Weetabix East Africa is allocated to NCI. The Company holds an equity interest in Alpen Food Company South Africa (Pty) Limited (“Alpen”). 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, net of tax, attributable to Alpen was $0.3, $0.5 and $0.4 for the years ended September 30, 2023, 2022 and 2021, respectively, and was included in “Equity method loss, net of tax” in the Consolidated Statements of Operations. The investment in Alpen was $3.6 and $4.1 at September 30, 2023 and 2022, respectively, and was included in “Other assets” on the Consolidated Balance Sheets. The Company had a note receivable balance with Alpen of $0.4 at both September 30, 2023 and 2022, respectively, which was included in “Other assets” on the Consolidated Balance Sheets.

Business Combinations

Business Combinations	12 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
Business Combinations	BUSINESS COMBINATIONS Fiscal 2023 On April 28, 2023, the Company completed its acquisition of a portion of The J. M. Smucker Company’s (“Smucker”) pet food business, including brands such as Rachael Ray Nutrish , Nature’s Recipe , 9Lives , Kibbles ’n Bits and Gravy Train , private label pet food assets and certain manufacturing and distribution facilities (collectively, “Pet Food”), facilitating the Company’s entry into the pet food category. The purchase price of the Pet Food acquisition was $1,207.5 which included (i) $700.0 in cash, subject to inventory adjustments, resulting in a payment at closing of $715.5, (ii) 5.4 million shares of Post common stock, or $492.3, and (iii) immaterial working capital adjustments. The cash payment was made using cash on hand, including proceeds from the Fourth Incremental Term Loan (as defined in Note 16). Pet Food is reported in the Post Consumer Brands segment. Based upon the purchase price allocation, the Company recorded $235.0 of trademarks and licensing agreements and $391.0 of customer relationships, both of which are being amortized over a weighted-average useful life of 18 years. Net sales included in the Consolidated Statements of Operations attributable to Pet Food was $679.8 for the year ended September 30, 2023. Due to the level of integration of Pet Food within the Post Consumer Brands segment, it is impracticable to separately present net earnings included in the Consolidated Statements of Operations attributable to Pet Food. The goodwill generated by the Company’s Pet Food acquisition is expected to be deductible for U.S. income tax purposes. The following table presents the purchase price allocation, including immaterial measurement period adjustments, related to the Pet Food acquisition based upon the fair values of assets acquired and liabilities assumed as of September 30, 2023. Inventories $ 205.8 Prepaid expenses and other current assets 0.5 Property 192.9 Other intangible assets 626.0 Deferred tax asset 2.7 Other assets 0.3 Other current liabilities (14.7) Other liabilities (0.2) Total identifiable net assets 1,013.3 Goodwill 194.2 Fair value of total consideration transferred $ 1,207.5 In connection with the Pet Food acquisition, the Company and Smucker entered into a transition services agreement (the “TSA”) pursuant to which Smucker provides certain Pet Food support services to Post for a transition period of 18 months (or up to 24 months at Post’s election) following the close of the acquisition based on the terms set forth in the TSA. Pet Food support services include, but are not limited to, certain sales, marketing, finance, information technology, procurement and supply chain services. During the year ended September 30, 2023 , Post incurred $10.0 related to TSA fees, which were recorded within “Selling, general and administrative expenses” in the Consolidated Statements of Operations. In accordance with the terms of the TSA, Smucker collects sales receivables from and remits payments to customers and vendors, respectively, in accordance with Smucker’s existing contractual terms. Pet Food receivables and payables are settled between Post and Smucker monthly on a net basis per the terms of the TSA. As of September 30, 2023 , the Company had recorded a net receivable due from Smucker of $35.5, which was recorded within “Receivables, net” on the Consolidated Balance Sheets. Fiscal 2022 On April 5, 2022, the Company completed its acquisition of Lacka Foods Limited (“Lacka Foods”), a U.K.-based distributor and marketer of protein-based shakes and nutritional snacks, for £24.5 million (approximately $32.2), net of cash acquired, using cash on hand. The acquisition included earnings-based contingent consideration of £3.5 million (approximately $4.6), representing its initial fair value estimate, which may be paid to the seller in annual installments over three years with a maximum cash payout of £3.5 million. During the year ended September 30, 2023, the Company paid £1.5 million (approximately $1.9) related to the earnings-based contingent consideration, which was reported as a cash flow from financing activities in “Other, net” on the Consolidated Statements of Cash Flows. Lacka Foods is reported in the Weetabix segment. Fiscal 2021 On June 1, 2021, the Company completed its acquisition of the private label RTE cereal business from TreeHouse Foods, Inc. (the “PL RTE Cereal Business”) for $85.0, subject to inventory and other adjustments, resulting in a payment at closing of $88.0. The acquisition was completed using cash on hand. The PL RTE Cereal Business is reported in the Post Consumer Brands segment. Based on the purchase price allocation at September 30, 2021, the Company identified and recorded $99.5 of net assets, which exceeded the purchase price paid for the PL RTE Cereal Business. As a result, the Company recorded a gain of $ 11.5 On May 27, 2021, the Company completed its acquisition of Egg Beaters from Conagra Brands, Inc. for $50.0, subject to working capital and other adjustments, resulting in a payment at closing of $50.6. The acquisition was completed using cash on hand. Egg Beaters is a retail liquid egg brand and is reported in the Refrigerated Retail segment. On February 1, 2021, the Company completed its acquisition of the Almark Foods business and related assets (“Almark”) for $52.0, subject to working capital and other adjustments, resulting in a payment at closing of $51.3. The acquisition was completed using cash on hand. The Company reached a final settlement of net working capital in fiscal 2022, resulting in an amount received by the Company of $2.9. Almark is a provider of hard-cooked and deviled egg products, offering conventional, organic and cage-free products, and distributes its products to foodservice distributors, as well as across retail outlets, including in the perimeter-of-the-store and the deli counter. Almark is reported in the Foodservice and Refrigerated Retail segments. On January 25, 2021, the Company completed its acquisition of Peter Pan from Conagra Brands, Inc. for $102.0, subject to working capital and other adjustments, resulting in a payment at closing of $103.4. The acquisition was completed using cash on hand. The Company reached a final settlement of net working capital in fiscal 2021, resulting in an amount received by the Company of $2.0. Peter Pan is a nationally recognized brand with a diversified customer base across key channels and is reported in the Post Consumer Brands segment. All Peter Pan nut butter products are currently co-manufactured by 8th Avenue, in which the Company has a 60.5% common equity interest (see Note 5). Acquisition-Related Expenses The Company incurs acquisition-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, 2023, 2022 and 2021, the Company incurred acquisition-related expenses of $17.8, $3.2 and $6.4, 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 results of operations of the Company combined with the results of the fiscal 2023 Pet Food acquisition and the fiscal 2021 acquisitions. The results of operations for the fiscal 2022 acquisition of Lacka Foods were immaterial for presentation within the following unaudited pro forma information. The years ended September 30, 2023 and 2022 present a summary of the results of operations of the Company combined with the results of the fiscal 2023 Pet Food acquisition as if the fiscal 2023 Pet Food acquisition had occurred on October 1, 2021, along with certain pro forma adjustments. The year ended September 30, 2021 presents a summary of the results of operations of the Company combined with the the fiscal 2021 acquisitions as if the acquisitions had occurred on October 1, 2019, along with certain pro forma adjustments. The fiscal 2021 acquisitions did not affect the unaudited pro forma information presented for the years ended September 30, 2023 or 2022. The pro forma adjustments give effect to the amortization of certain definite-lived intangible assets, adjusted depreciation based upon fair value of assets acquired, acquisition-related costs, inventory revaluation adjustments, interest expense, TSA fees, gain on bargain purchase 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 acquisitions occurred on the assumed date, nor is it necessarily an indication of future operating results. Year Ended September 30, 2023 2022 2021 Pro forma net sales $ 7,902.9 $ 7,360.2 $ 5,184.3 Pro forma net earnings from continuing operations $ 354.2 $ 607.0 $ 96.9 Pro forma basic earnings from continuing operations per common share $ 5.78 $ 9.15 $ 1.51 Pro forma diluted earnings from continuing operations per common share $ 5.36 $ 8.93 $ 1.48

Divestitures and Amounts Held F

Divestitures and Amounts Held For Sale	12 Months Ended
	Sep. 30, 2023
Assets and Liabilities Held for Sale [Abstract]
Divestitures and Amounts Held For Sale	DIVESTITURES AND AMOUNTS HELD FOR SALE Divestiture On December 1, 2021, the Company sold the Willamette Egg Farms business (the “WEF Transaction”), which included the sale of $62.8 book value of assets, for total proceeds of $56.1. Of the $56.1, the Company had $6.0 in escrow, subject to certain contingencies, which was included in “Receivables, net” on the Consolidated Balance Sheets at September 30, 2022 . During the year ended September 30, 2023, the Company received $4.6 of the proceeds held in escrow, which reduced the amount in escrow to $1.4 as of September 30, 2023. As a result of the WEF Transaction, during the year ended September 30, 2022 , the Company recorded a net loss on sale of business of $6.3, which included a favorable working capital adjustment of $0.4, and was reported as “Other operating expense (income), net” in the Consolidated Statements of Operations. Subsequent to the WEF Transaction, Willamette Egg Farms was no longer consolidated in the Company’s financial statements. Prior to the WEF Transaction, Willamette Egg Farms’ operating results were reported in the Refrigerated Retail segment. There were no gains or losses on sale of business recorded during the years ended September 30, 2023 or 2021. Amounts Held For Sale In the year ended September 30, 2022, a net gain on assets held for sale of $ 9.4 9.8 0.4 Equipment was classified as held for sale and was reported as “Prepaid expenses and other current assets” on the Consolidated Balance Sheets. The Jefferson City Equipment sale closed in fiscal 2023. In the year ended September 30, 2021, a net gain on assets held for sale of $ 0.5 0.7 0.1 0.1 The above held for sale gains and losses were included in “Other operating expense (income), net” in the Consolidated Statements of Operations for the years ended September 30, 2022 and 2021. There were no held for sale gains or losses recorded in the year ended September 30, 2023.

Goodwill

Goodwill	12 Months Ended
	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL The changes in the carrying amount of goodwill by segment are presented in the following table. Post Consumer Brands Weetabix Foodservice Refrigerated Retail Total Balance, September 30, 2021 Goodwill (gross) $ 2,067.1 $ 929.4 $ 1,355.0 $ 807.9 $ 5,159.4 Accumulated impairment losses (609.1) — — (48.7) (657.8) Goodwill (net) $ 1,458.0 $ 929.4 $ 1,355.0 $ 759.2 $ 4,501.6 Goodwill from acquisitions (a) — 13.9 0.3 — 14.2 Sale of business (b) — — — (4.2) (4.2) Currency translation adjustment (0.3) (161.7) — — (162.0) Balance, September 30, 2022 Goodwill (gross) $ 2,066.8 $ 781.6 $ 1,355.3 $ 803.7 $ 5,007.4 Accumulated impairment losses (609.1) — — (48.7) (657.8) Goodwill (net) $ 1,457.7 $ 781.6 $ 1,355.3 $ 755.0 $ 4,349.6 Goodwill from acquisition 194.2 — — — 194.2 Impairment loss — — — (42.2) (42.2) Currency translation adjustment 0.1 72.7 — — 72.8 Balance, September 30, 2023 Goodwill (gross) $ 2,261.1 $ 854.3 $ 1,355.3 $ 803.7 $ 5,274.4 Accumulated impairment losses (609.1) — — (90.9) (700.0) Goodwill (net) $ 1,652.0 $ 854.3 $ 1,355.3 $ 712.8 $ 4,574.4 (a) In fiscal 2022, the Company recorded $13.9 of goodwill related to the Lacka Foods acquisition and also recorded a final measurement period adjustment of $0.3 related to the Almark acquisition. For additional information on the Company’s acquisitions, see Note 6. (b) In December 2021, the Company completed the WEF Transaction. For additional information on the WEF Transaction, see Note 7. During the year ended September 30, 2023 , the Company recorded a goodwill impairment charge of $42.2 related to its Cheese and Dairy reporting unit within the Refrigerated Retail segment, which was recorded in “Impairment of goodwill” in the Consolidated Statements of Operations. The goodwill impairment charge was driven primarily by narrowing of the pricing gap between branded and private label competitors, resulting in distribution losses and declining profitability. See Note 14 for additional information on the significant assumptions utilized in the estimate of the fair value of the Cheese and Dairy reporting unit. The Company did not record a goodwill impairment charge during the years ended September 30, 2022 or 2021, as all reporting units subjected to the quantitative test passed during each respective year. At September 30, 2023 , the Weetabix reporting unit fair value exceeded its carrying value by approximately 6.4% and was impacted by raw material and energy cost inflation as well as U.K. economic pressures negatively impacting consumer spending trends, both of which impacted near-term profitability. The Company expects these impacts to be transitory in nature; however, inherent risk to the reporting unit’s cash flows remains. Variances between the actual performance of the reporting unit and the assumptions that were used in developing the estimate of fair value could result in impairment charges in future periods. The estimated fair values of all other reporting units exceeded their carrying values by at least 13% at September 30, 2023 . At September 30, 2022, the Cheese and Dairy reporting unit and the Refrigerated Retail reporting unit fair values exceeded their carrying values by approximately 6.5% and 8.5%, respectively, and the estimated fair values of all other reporting units exceeded their carrying values by at least 10%. At September 30, 2021, the estimated fair values of all reporting units exceeded

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income taxes	INCOME TAXES The components of “Earnings before Income Taxes and Equity Method Loss” in the Consolidated Statements of Operations and other summary information is presented in the following table. Year Ended September 30, 2023 2022 2021 Domestic $ 397.2 $ 799.9 $ 105.9 Foreign 15.7 95.4 108.1 Earnings before Income Taxes and Equity Method Loss $ 412.9 $ 895.3 $ 214.0 Income tax expense $ 99.7 $ 85.7 $ 58.2 Effective income tax rate 24.1 % 9.6 % 27.2 % Income tax expense consisted of the following: Year Ended September 30, 2023 2022 2021 Current: Federal $ 96.4 $ 71.1 $ (20.3) State 21.0 11.1 (0.2) Foreign 5.2 13.2 10.5 122.6 95.4 (10.0) Deferred: Federal (10.7) (9.7) 22.6 State (11.8) — 3.4 Foreign (0.4) — 42.2 (22.9) (9.7) 68.2 Income tax expense $ 99.7 $ 85.7 $ 58.2 The following table presents the reconciliation of income tax expense with amounts computed at the U.S. federal statutory tax rate. Year Ended September 30, 2023 2022 2021 Computed tax at federal statutory rate (21%) $ 86.7 $ 188.0 $ 44.9 State income tax, net of effect on federal tax 12.2 10.3 1.7 Non-deductible goodwill impairment charge 8.9 — — Non-deductible compensation 7.0 5.9 5.4 Valuation allowances 1.0 1.4 2.9 Enacted tax law and changes in deferred tax rates (5.8) 0.9 40.0 Excess tax benefits for share-based payments (5.7) (3.6) (6.1) Income tax credits (2.4) (1.9) (1.5) Enhanced deduction for food donations (1.6) (1.0) (0.8) Gain on investment in BellRing (a) (1.1) (91.8) — Rate differential on foreign income (0.2) (10.2) (11.0) Return-to-provision and changes in prior year accruals (0.1) (0.5) (2.8) Net losses and basis difference attributable to equity method investment — (14.1) (9.2) Gain on bargain purchase — — (2.4) Other, net (none in excess of 5% of statutory tax) 0.8 2.3 (2.9) Income tax expense $ 99.7 $ 85.7 $ 58.2 (a) No income taxes have been recorded with respect to the non-cash realized and unrealized book gains on the Company’s Investment in BellRing during the years ended September 30, 2023 or 2022, as the Company fully divested its Investment in BellRing within 12 months of the BellRing Spin-off in a manner intended to qualify as tax-free for U.S. federal income tax purposes. For additional information on our Investment in BellRing, refer to Notes 4, 5 and 16. 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. Non-current deferred tax assets (liabilities) were as follows: September 30, 2023 September 30, 2022 Assets Liabilities Net Assets Liabilities Net Disallowed interest carryforwards $ 53.9 $ — $ 53.9 $ 55.4 $ — $ 55.4 Lease liabilities 49.1 — 49.1 35.8 — 35.8 Derivatives, equity securities and investment adjustments 41.0 — 41.0 34.9 — 34.9 Net operating loss and credit carryforwards 20.9 — 20.9 24.1 — 24.1 Stock-based and deferred compensation 20.6 — 20.6 19.9 — 19.9 Inventory 16.0 — 16.0 8.8 — 8.8 Capitalized research and development 11.2 — 11.2 — — — Accrued liabilities 10.8 — 10.8 7.0 — 7.0 Accrued vacation, incentive and severance 10.3 — 10.3 6.2 — 6.2 Basis difference attributable to equity method investment 4.7 — 4.7 4.6 — 4.6 Intangible assets — (592.2) (592.2) — (611.4) (611.4) Property — (226.1) (226.1) — (197.6) (197.6) ROU assets — (46.2) (46.2) — (32.9) (32.9) Pension and other postretirement benefits — (16.2) (16.2) — (11.4) (11.4) Other items 6.9 (2.7) 4.2 5.5 (1.8) 3.7 Total gross deferred income taxes 245.4 (883.4) (638.0) 202.2 (855.1) (652.9) Valuation allowance (36.4) — (36.4) (35.5) — (35.5) Total deferred income taxes $ 209.0 $ (883.4) $ (674.4) $ 166.7 $ (855.1) $ (688.4) As of September 30, 2023, the Company’s $20.9 deferred tax asset for net operating loss (“NOL”) and credit carryforwards is comprised of state NOLs of $11.5, foreign tax loss carryforwards of $5.1, state credit carryforwards of $2.6 and U.S. federal NOL carryforwards of $1.7. The expiration for the majority of these carryforwards are either greater than 10 years or are able to be carried forward indefinitely. The Company has offset approximately $11.4 of the $11.5 state NOLs and all of the $5.1 of foreign tax loss carryforwards 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. In addition, as of September 30, 2023, the Company had a deferred tax asset for disallowed U.S. interest expense of $53.9 subject to Internal Revenue Code Section 163(j) limitations, which may be carried forward indefinitely. Based on management’s judgement, with the exception of a $6.0 valuation allowance recorded for state-related disallowed interest carryforwards, it is more likely than not that the Company will recognize the benefit of this deferred tax asset in the future. As of September 30, 2023 and 2022, the Company had a valuation allowance of $36.4 and $35.5, respectively, based on management’s judgment that it is more likely than not that the benefits of its deferred tax assets will not be realized in the future. The changes in the valuation allowance during the years ended September 30, 2023, 2022 and 2021 were $0.9, $(6.1) and $0.5, respectively. These changes primarily relate to valuation allowances on state carryforwards. The Company generally repatriates a portion of current year earnings from select non-U.S. subsidiaries only if the economic cost of the repatriation is not considered material. No provision has been made for income taxes on the Company’s undistributed earnings of consolidated foreign subsidiaries of $106.2 as of September 30, 2023, as it is the Company’s intention to indefinitely reinvest undistributed earnings of its foreign subsidiaries to, amongst other things, fund local operations, fund debt service payments, fund pension and other post-retirement obligations, fund capital projects and support foreign growth initiatives, including potential acquisitions. If the Company repatriated any of the earnings, it could be subject to withholding tax and the impact of foreign currency movements. 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. Applicable income and withholding taxes will be provided on these earnings in the periods in which they are no longer considered reinvested. U.K. Tax Law Changes In fiscal 2021, the effective income tax rate was impacted by enacted tax law changes in the U.K., which included a provision to increase the U.K.’s corporate income tax rate from 19% to 25%, effective April 1, 2023. During the years ended September 30, 2023, 2022 and 2021, the Company measured its existing deferred tax assets and liabilities considering the 25% U.K. corporate income tax rate for future periods and recorded tax expense of $0.7, $0.9 and $40.0, respectively. Other changes made to the U.K.’s tax laws did not have a material impact on the Company’s financial statements during the years ended September 30, 2023, 2022 or 2021. 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 is presented in the following table. As of and for the Year Ended September 30, 2023 2022 2021 Balance, beginning of year $ 11.7 $ 12.5 $ 8.3 Additions for tax positions taken in current year and acquisitions 0.8 0.1 0.3 Additions for tax positions taken in prior years 0.4 — 5.2 Settlements with tax authorities/statute expirations (0.1) (0.9) (1.3) Balance, end of year $ 12.8 $ 11.7 $ 12.5 The amount of the net unrecognized tax benefits that, if recognized, would directly affect the effective income tax rate was $7.6 at September 30, 2023. 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 $5.3 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 expense (benefit). The Company recorded income tax expense (benefit) of $0.5, $0.1 and $(0.5) related to interest and penalties in the years ended September 30, 2023, 2022 and 2021, respectively. The Company had accrued interest and penalties of $1.1 and $0.6 at September 30, 2023 and 2022, 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, 2020 through September 30, 2022 are generally open and subject to examination by the tax authorities in each respective jurisdiction.

Earnings per Share

Earnings per Share	12 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Earnings per Share	EARNINGS PER SHARE The following table sets forth the computation of basic and diluted earnings per share for both continuing and discontinued operations. Year Ended September 30, 2023 2022 2021 Net Earnings from Continuing Operations Net earnings from continuing operations $ 301.3 $ 735.0 $ 104.9 Impact of redeemable NCI 11.0 — (11.0) Net earnings from continuing operations for basic earnings per share $ 312.3 $ 735.0 $ 93.9 Impact of interest expense, net of tax, related to convertible senior notes 10.9 1.5 — Net earnings from continuing operations for diluted earnings per share $ 323.2 $ 736.5 $ 93.9 Net Earnings from Discontinued Operations Net earnings from discontinued operations for basic earnings per share $ — $ 21.6 $ 61.8 Dilutive impact of Old BellRing net earnings from discontinued operations — — (0.1) Net earnings from discontinued operations for diluted earnings per share $ — $ 21.6 $ 61.7 Net Earnings Net earnings for basic earnings per share $ 312.3 $ 756.6 $ 155.7 Net earnings for diluted earnings per share $ 323.2 $ 758.1 $ 155.6 shares in millions Weighted-average shares for basic earnings per share 60.0 60.9 64.2 Effect of dilutive securities: Stock options 0.4 0.3 0.6 Stock appreciation rights — 0.1 0.1 Restricted stock units 0.5 0.5 0.3 Market-based performance restricted stock units 0.6 0.1 0.1 Earnings-based performance restricted stock units 0.1 0.1 — Shares issuable upon conversion of convertible senior notes 5.4 0.7 — Total dilutive securities 7.0 1.8 1.1 Weighted-average shares for diluted earnings per share 67.0 62.7 65.3 Earnings from Continuing Operations per Common Share: Basic $ 5.21 $ 12.07 $ 1.46 Diluted $ 4.82 $ 11.75 $ 1.44 Earnings from Discontinued Operations per Common Share: Basic $ — $ 0.35 $ 0.96 Diluted $ — $ 0.34 $ 0.94 Earnings per Common Share: Basic $ 5.21 $ 12.42 $ 2.42 Diluted $ 4.82 $ 12.09 $ 2.38 The following table details the securities that have been excluded from the calculation of weighted-average shares for diluted earnings per share for both continuing and discontinued operations as they were anti-dilutive. Year Ended September 30, 2023 2022 2021 Restricted stock units 0.1 0.3 — Market-based performance restricted stock units 0.1 0.1 —

Supplemental Operations Stateme

Supplemental Operations Statement and Cash Flow Information	12 Months Ended
	Sep. 30, 2023
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, 2023 2022 2021 Advertising expenses $ 124.1 $ 93.2 $ 112.3 Research and development expenses 22.9 18.9 21.9 Interest income (20.9) (4.4) (0.6) Interest paid 300.2 320.0 348.2 Income taxes paid 114.7 45.8 45.6 Accrued additions to property 37.9 36.4 38.3

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	12 Months Ended
	Sep. 30, 2023
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	SUPPLEMENTAL BALANCE SHEET INFORMATION September 30, 2023 2022 Receivables, net Trade $ 451.0 $ 499.4 Pet Food net receivable (see Note 6) 35.5 — Income tax receivable 8.3 17.4 Related party 6.9 4.4 Other 13.2 25.3 514.9 546.5 Allowance for credit losses (2.5) (2.3) $ 512.4 $ 544.2 Inventories Raw materials and supplies $ 155.9 $ 130.9 Work in process 24.4 21.1 Finished products 573.6 361.9 Flocks 36.0 35.2 $ 789.9 $ 549.1 Other Assets Pension asset $ 110.3 $ 93.9 Operating ROU assets 176.2 122.9 Other investments 6.1 26.9 Derivative assets 11.3 3.0 Software implementation costs 18.0 — Other 38.1 24.2 $ 360.0 $ 270.9 Accounts Payable Trade $ 339.7 $ 362.1 Book cash overdrafts 1.3 53.3 Related party 13.8 26.1 Other 14.0 11.2 $ 368.8 $ 452.7 Other Current Liabilities Advertising and promotion $ 74.0 $ 47.2 Accrued interest 67.0 69.5 Accrued compensation 128.2 63.4 Derivative liabilities 16.1 25.9 Operating lease liabilities 22.8 25.5 Accrued freight 16.4 25.1 Other accrued taxes 21.4 19.1 Other 89.5 94.3 $ 435.4 $ 370.0 Other Liabilities Pension and other postretirement benefit obligations $ 42.8 $ 45.6 Derivative liabilities — 49.1 Deferred compensation 36.2 33.1 Operating lease liabilities 169.6 113.7 Other 28.1 25.4 $ 276.7 $ 266.9

Derivative Financial Instrument

Derivative Financial Instruments and Hedging	12 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Hedging	DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGINGAt September 30, 2023, the Company’s derivative instruments, none of which were designated as hedging instruments under ASC Topic 815, 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 (the “FX contracts”) maturing in the next year that have the effect of hedging currency fluctuations between the Euro and the Pound Sterling; • pay-fixed, receive-variable interest rate swaps maturing in June 2033 that require monthly settlements and have the effect of hedging interest payments on debt expected to be issued but not yet priced; and • pay-fixed, receive-variable interest rate swaps maturing in April 2026 that require monthly settlements and have the effect of hedging forecasted interest payments on the Company’s Fourth Incremental Term Loan (as defined in Note 16). Interest rate swaps In fiscal 2023, the Company paid $55.1 in connection with the termination of $849.3 notional value of its rate-lock swap contracts, of which $43.5 related to the termination of rate-lock swap contracts that contained other-than-insignificant financing elements and were reported as cash flows from financing activities in the Consolidated Statements of Cash Flows. The Company also paid $2.1 in connection with the termination of $332.6 notional value of its interest rate swap option, and received cash proceeds of $6.7 in connection with the termination of its interest rate swap contract with a $200.0 notional value. In fiscal 2022, the Company paid $17.0 in connection with the termination of $700.0 notional value of its rate-lock swap contracts. The Company also restructured two of its rate-lock swap contracts, which contained other-than-insignificant financing elements. There were no cash settlements paid or received in connection with these restructurings. In fiscal 2021, the Company restructured four of its rate-lock swap contracts, which contained non-cash, off-market financing elements. There were no cash settlements paid or received in connection with these restructurings. The following table presents the notional amounts of derivative instruments held. September 30, 2023 2022 Commodity contracts $ 215.0 $ 145.0 Energy contracts 48.9 23.7 FX contracts 3.0 3.2 Interest rate swap 700.0 200.0 Interest rate swaps - Rate-lock swaps — 849.3 Interest rate swaps - Option — 332.6 PHPC Warrants — 16.9 The following table presents the balance sheet location and fair value of the Company’s derivative instruments. The Company does not offset derivative assets and liabilities within the Consolidated Balance Sheets. September 30, Balance Sheet Location 2023 2022 Asset Derivatives: Commodity contracts Prepaid expenses and other current assets $ 1.2 $ 12.9 Energy contracts Prepaid expenses and other current assets 2.5 13.6 Interest rate swaps Prepaid expenses and other current assets 10.6 3.4 Commodity contracts Other assets — 0.5 Interest rate swaps Other assets 11.3 2.5 $ 25.6 $ 32.9 Liability Derivatives: Commodity contracts Other current liabilities $ 14.1 $ 1.5 Energy contracts Other current liabilities 2.0 1.8 FX contracts Other current liabilities — 0.1 Interest rate swaps Other current liabilities — 22.5 Interest rate swaps Other liabilities — 48.1 PHPC Warrants Other liabilities — 1.0 $ 16.1 $ 75.0 The following table presents the statement of operations location and loss (gain) recognized related to the Company’s derivative instruments. Derivative Instruments Statement of Operations Location Year Ended September 30, 2023 2022 2021 Commodity contracts Cost of goods sold $ 28.5 $ (32.2) $ (11.3) Energy contracts Cost of goods sold 6.7 (28.5) (43.1) FX contracts Selling, general and administrative expenses (0.1) 0.1 0.1 Interest rate swaps Income on swaps, net (39.9) (268.0) (122.8) PHPC Warrants Other income, net (1.0) (8.2) (7.7) At September 30, 2023 and 2022, the Company had pledged collateral of $23.4 and $2.8, 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, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The following table presents the Company’s 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, 2023 September 30, 2022 Total Level 1 Level 2 Total Level 1 Level 2 Assets: Deferred compensation investments $ 13.0 $ 13.0 $ — $ 12.0 $ 12.0 $ — Derivative assets 25.6 — 25.6 32.9 — 32.9 Equity securities 0.2 0.2 — 32.1 32.1 — Investment in BellRing — — — 94.8 94.8 — $ 38.8 $ 13.2 $ 25.6 $ 171.8 $ 138.9 $ 32.9 Liabilities: Deferred compensation liabilities $ 36.8 $ — $ 36.8 $ 33.7 $ — $ 33.7 Derivative liabilities 16.1 — 16.1 75.0 1.0 74.0 $ 52.9 $ — $ 52.9 $ 108.7 $ 1.0 $ 107.7 Deferred Compensation The deferred compensation investments are primarily invested in mutual funds, and their fair value is measured using the market approach. These investments are in the same funds, or funds that employ a similar investment strategy, and are purchased in substantially the same amounts, as the participants’ selected notional 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 notional investment options (excluding certain Post common stock equivalents to be distributed in shares) using the market approach. Derivatives 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. FX 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 13 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. As of September 30, 2022, the PHPC Warrants were valued using the market approach based on quoted prices and were categorized as Level 1. The fair value of the PHPC Warrants was zero as of September 30, 2023, as the PHPC Warrants expired worthless in connection with the PHPC Redemption. For additional information on the PHPC Warrants, see Notes 5 and 13. Equity Securities and Investment in BellRing The Company uses the market approach to measure the fair value of its equity securities. The Investment in BellRing represented the Company’s 3.4% equity interest in BellRing as of September 30, 2022, which was measured at its fair value of $94.8 based on the trading value of the BellRing Common Stock on September 30, 2022. As of September 30, 2023, the Company did not hold an equity interest in BellRing. For additional information on the Investment in BellRing, see Notes 4 and 5. Other Fair Value Measurements Investments held in trust held prior to the PHPC Redemption were invested in a fund consisting entirely of U.S. treasury securities. The fund was valued at net asset value (“NAV”) per share, and as such, in accordance with ASC Topic 820, the investments were not classified in the fair value hierarchy. Investments held in trust were reported at fair value on the Consolidated Balance Sheets as of September 30, 2022. In connection with the PHPC Redemption, the investments held in trust were liquidated and the proceeds were disbursed to PHPC’s public stockholders, including $40.9 to the Company, during fiscal 2023. For additional information, see Note 5. 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 any outstanding borrowings under the municipal bond as of September 30, 2023 and 2022 approximated their carrying values. Based on current market rates, the fair value (Level 2) of the Company’s debt, excluding outstanding borrowings under the muni cipal bond (which are also categorized as Level 2), was $5,491.5 and $5,171.0 as of September 30, 2023 and 2022, respectively, which included $572.6 and $566.1 related to the Company’s convertible senior notes, respectively. Certain assets and liabilities, including property, goodwill, other intangible assets and assets held for sale, are measured at fair value on a non-recurring basis using Level 3 inputs. During the year ended September 30, 2023, the Company recorded a goodwill impairment charge of $42.2 related to its Cheese and Dairy reporting unit within the Refrigerated Retail segment, which was recorded in “Impairment of goodwill” in the Consolidated Statements of Operations. There were no goodwill impairment charges recorded during the years ended September 30, 2022 or 2021. For additional information on goodwill, see Notes 2 and 8. During fiscal 2022, the Company sold the Klingerstown Equipment and entered into an agreement to sell the Jefferson City Equipment, which subsequently closed in fiscal 2023. The Klingerstown Equipment and the Jefferson City Equipment were reported in the Foodservice segment. For additional information on assets held for sale, see Note 7. The fair value of assets held for sale was measured on a non-recurring basis based on the lower of the carrying amount or fair value less cost to sell. When applicable, the fair value is adjusted to reflect an offer to purchase the assets. The fair value measurements were categorized as Level 3, as the fair values utilize significant unobservable inputs. The following table summarizes the Level 3 activity. Balance, September 30, 2021 $ — Net gain related to assets held for sale 9.4 Proceeds from the sale of assets held for sale (10.3) Transfers of assets into held for sale 1.0 Balance, September 30, 2022 $ 0.1 Proceeds from the sale of assets held for sale (0.1) Balance, September 30, 2023 $ —

Leases

Leases	12 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Lessee, Operating Leases	LEASES The Company leases office space, certain warehouses, manufacturing facilities and equipment primarily through operating lease agreements. The Company has no material finance lease agreements. Leases have remaining terms which range from less than 1 to 53 years and most leases provide the Company with the option to exercise one or more renewal terms. The following table presents the balance sheet location of the Company’s operating leases. September 30, 2023 2022 ROU assets: Other assets $ 176.2 $ 122.9 Lease liabilities: Other current liabilities $ 22.8 $ 25.5 Other liabilities 169.6 113.7 Total lease liabilities $ 192.4 $ 139.2 Future minimum payments of the Company’s operating lease liabilities as of September 30, 2023 are presented in the following table. Fiscal 2024 $ 33.5 Fiscal 2025 37.1 Fiscal 2026 36.9 Fiscal 2027 32.8 Fiscal 2028 27.1 Thereafter 75.2 Total future minimum payments $ 242.6 Less: Implied interest 50.2 Total lease liabilities $ 192.4 The following table presents supplemental information related to the Company’s operating leases. Year Ended September 30, 2023 2022 2021 Total operating lease expense $45.8 $45.5 $40.1 Variable lease expense 5.3 5.2 4.8 Short-term lease expense 7.7 9.4 7.5 Weighted-average remaining lease term 8 years 9 years 9 years Weighted-average IBR 5.99% 5.26% 4.70%

Long Term Debt

Long Term Debt	12 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Long-term Debt	LONG-TERM DEBT The components of “Long-term debt” on the Consolidated Balance Sheets are presented in the following table. September 30, 2023 2022 2.50% convertible senior notes maturing August 2027 $ 575.0 $ 575.0 4.50% senior notes maturing September 2031 1,049.7 1,270.5 4.625% senior notes maturing April 2030 1,385.4 1,482.2 5.50% senior notes maturing December 2029 1,235.0 1,235.0 5.625% senior notes maturing January 2028 939.9 940.9 5.75% senior notes maturing March 2027 459.3 459.3 Fourth Incremental Term Loan 400.0 — Municipal bond 5.3 6.4 $ 6,049.6 $ 5,969.3 Less: Current portion of long-term debt 1.1 1.1 Debt issuance costs, net 42.0 50.1 Plus: Unamortized premium, net 32.5 38.5 Total long-term debt $ 6,039.0 $ 5,956.6
Long-Term Debt - BRBR	Debt Transactions in Connection with BellRing On March 8, 2022, the Company entered into a Joinder Agreement No. 1 (the “First Joinder Agreement”) by and among the Company, as borrower, certain of the Company’s subsidiaries, as guarantors, the institutions constituting the Funding Incremental Term Loan Lenders (as defined in the First Joinder Agreement, referred to herein as the “First Funding Incremental Term Loan Lenders”), Barclays Bank PLC, as administrative agent, and JPMorgan Chase Bank, N.A., as sub-agent to the administrative agent. The First Joinder Agreement provided for an incremental term loan (the “First Incremental Term Loan”) of $840.0 under the Company’s Credit Agreement (as defined below), which the Company borrowed in full on March 8, 2022. The First Joinder Agreement permitted the Company to repay the First Incremental Term Loan, in whole or in part, in cash or, with the prior written consent of the First Funding Incremental Term Loan Lenders, in lieu of cash, to exchange its obligations under the First Incremental Term Loan with the First Funding Incremental Term Loan Lenders for the BellRing Notes. On March 10, 2022, the Company and the First Funding Incremental Term Loan Lenders entered into an exchange agreement (the “First Exchange Agreement”) pursuant to which the Company repaid the First Incremental Term Loan and all accrued and unpaid interest and expenses owed thereunder through a combination of (i) with respect to the principal amount owed under the First Incremental Term Loan, the assignment and transfer by the Company of all $840.0 of the BellRing Notes to the First Funding Incremental Term Loan Lenders and (ii) with respect to accrued and unpaid interest and fees and expenses owed under the First Incremental Term Loan, cash on hand (collectively, the “Debt-for-Debt Exchange”). As provided in the First Exchange Agreement, upon completion of the transfer of the BellRing Notes to the First Funding Incremental Term Loan Lenders and payment of interest, fees and expenses, the First Incremental Term Loan was deemed satisfied and paid in full. For additional information, see “Repayments of Debt” below. On March 17, 2022, the Company redeemed $840.0 in aggregate principal amount, or approximately 65%, of the outstanding 5.75% senior notes maturing in March 2027 using the proceeds from the First Incremental Term Loan. The 5.75% senior notes were redeemed at a redemption price of 102.875% of the aggregate principal amount of the 5.75% senior notes being redeemed, plus accrued and unpaid interest for each day from March 1, 2022 to, but excluding, March 17, 2022. For additional information, see “Repayments of Debt” below. On July 25, 2022, the Company entered into a Joinder Agreement No. 2 (the “Second Joinder Agreement”) by and among the Company, as borrower, certain of the Company’s subsidiaries, as guarantors, the institutions constituting the Funding Incremental Term Loan Lenders (as defined in the Second Joinder Agreement, referred to herein as the “Second Funding Incremental Term Loan Lenders”), Barclays Bank PLC, as administrative agent, and JPMorgan Chase Bank, N.A., as sub-agent to the administrative agent. The Second Joinder Agreement provided for an incremental term loan (the “Second Incremental Term Loan”) of $450.0 under the Company’s Credit Agreement, which the Company borrowed in full on July 25, 2022. The Second Joinder Agreement permitted the Company to repay the Second Incremental Term Loan, in whole or in part, in cash or, with the prior written consent of the Second Funding Incremental Term Loan Lenders, with an alternative form of consideration in lieu of cash. On August 8, 2022, the Company and the Second Funding Incremental Term Loan Lenders entered into an exchange agreement (the “Second Exchange Agreement”) pursuant to which the Company transferred on August 11, 2022 14.8 million shares of its Investment in BellRing to the Second Funding Incremental Term Loan Lenders to repay $342.3 in aggregate principal amount of the Second Incremental Term Loan, excluding accrued interest, which was paid with cash (such exchange, the “First Debt-for-Equity Exchange”). On September 14, 2022, the Company repaid the remaining principal balance of $107.7 of the Second Incremental Term Loan using cash on hand. For additional information, see “Repayments of Debt” below. On November 18, 2022, the Company entered into a Joinder Agreement No. 3 (the “Third Joinder Agreement”) by and among the Company, as borrower, certain of the Company’s subsidiaries, as guarantors, J.P. Morgan Securities LLC (“J.P. Morgan”), as lender, Barclays Bank PLC, as administrative agent, and JPMorgan Chase Bank, N.A., as sub-agent to the administrative agent. The Third Joinder Agreement provided for an incremental term loan (the “Third Incremental Term Loan”) of $130.0 under the Company’s Credit Agreement, which the Company borrowed in full on November 18, 2022. Interest on the Third Incremental Term Loan accrued at the adjusted term secured overnight financing rate (“SOFR”) (as defined in the Credit Agreement) plus a margin of 1.50% per annum, and the maturity date for the Third Incremental Term Loan was December 19, 2022. The Third Joinder Agreement permitted the Company to repay the Third Incremental Term Loan, in whole or in part, in cash or, with the prior written consent of J.P. Morgan, with an alternative form of consideration in lieu of cash. On November 21, 2022, the Company and J.P. Morgan entered into an exchange agreement (the “Third Exchange Agreement”) pursuant to which the Company transferred, on November 25, 2022, the remaining 4.6 million shares of its Investment in BellRing to J.P. Morgan to repay $99.9 in aggregate principal amount of the Third Incremental Term Loan, excluding accrued interest, which was paid with cash (such exchange, the “Second Debt-for-Equity Exchange”). Following the completion of the Second Debt-for-Equity Exchange, the Company no longer held shares of BellRing Common Stock. On
Long-Term Debt - Convertible Sr Note	Convertible Senior Notes On August 12, 2022, the Company issued $575.0 principal value of 2.50% convertible senior notes maturing in August 2027. The 2.50% convertible senior notes were issued at par, and the Company received $559.1 after incurring investment banking and other fees and expenses of $15.9, which were deferred and are being amortized to interest expense over the term of the 2.50% convertible senior notes. Interest payments on the 2.50% convertible senior notes are due semi-annually each February 15 and August 15, which began on February 15, 2023. The initial conversion rate of the 2.50% convertible senior notes is 9.4248 shares of the Company’s common stock per one thousand dollars principal amount of the 2.50% convertible senior notes, which represents an initial conversion price of approximately $106.10 per share of common stock. The conversion rate, and thus the conversion price, may be adjusted under certain circumstances as described in the indenture governing the 2.50% convertible senior notes (the “Convertible Notes Indenture”). The Company may settle conversions by paying or delivering, as applicable, cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election. If a “make-whole fundamental change” (as defined in the Convertible Notes Indenture) occurs, then the Company must in certain circumstances increase the conversion rate for a specified period of time. The 2.50% convertible senior notes may be converted at the holder’s option up to the second scheduled trading day immediately before the maturity date of August 15, 2027 under the following circumstances: • during any calendar quarter (and only during such calendar quarter) commencing after the calendar quarter ended September 30, 2022, if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter; • during the five consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “Measurement Period”) in which the trading price per one thousand dollars principal amount of the 2.50% convertible senior notes for each trading day of the Measurement Period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; • upon the occurrence of certain corporate events or distributions on the Company’s common stock described in the Convertible Notes Indenture; • if the Company calls the 2.50% convertible senior notes for redemption; and • at any time from, and including, May 15, 2027 until the close of business on the second scheduled trading day immediately before the August 15, 2027 maturity date. If a “fundamental change” (as defined in the Convertible Notes Indenture) occurs, then, except as described in the Convertible Notes Indenture, holders of the 2.50% convertible senior notes may require the Company to repurchase their 2.50% convertible senior notes at a cash repurchase price equal to the principal amount of the 2.50% convertible senior notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the “fundamental change repurchase date” (as defined in the Convertible Notes Indenture). The 2.50% convertible senior notes may be redeemed, in whole or in part (subject to the partial redemption limitation described in the Convertible Notes Indenture), at the Company’s option at any time, and from time to time, on or after August 20, 2025 and on or before the 35th scheduled trading day immediately before August 15, 2027, at a cash redemption price equal to the principal amount of the 2.50% convertible senior notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, only if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on (i) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice, and (ii) the trading day immediately before the date the Company sends such notice. As of both September 30, 2023 and 2022 , none of the conditions permitting holders to convert their 2.50% convertible senior notes had been satisfied, and no shares of the Company’s common stock had been issued in connection with any conversions of the 2.50% convertible senior notes. The 2.50% convertible senior notes have no embedded features that required separate bifurcation under ASC Topic 815. As such, the 2.50% convertible senior notes were recorded at the principal amount, net of unamortized issuance costs, on the Company’s Consolidated Balance Sheets as of both September 30, 2023 and 2022. As of September 30, 2023 and 2022, the net carrying value of the 2.50% convertible senior notes was $562.4 and $559.5, respectively, which included $12.6 and $15.5, respectively, of unamortized debt issuance costs.
Long-Term Debt - Other Sr Notes	Other Senior Notes On February 14, 2017, the Company issued $750.0 principal value of 5.75% senior notes maturing in March 2027. The 5.75% senior notes were issued at par, and the Company received $739.5 after incurring investment banking and other fees and expenses of $10.5, which were deferred and are being amortized to interest expense over the term of the 5.75% senior notes. On August 10, 2017, the Company issued an additional $750.0 principal value of 5.75% senior notes. The additional 5.75% senior notes were issued at a price of 105.5% of par value, and the Company received $784.0 after incurring investment banking and other fees and expenses 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 additional 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 5.75% senior 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 incurring investment banking and other fees and expenses of $9.4, which were deferred and are being amortized to interest expense over the term of the 5.625% senior 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 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 5.50% senior notes. On December 22, 2021, the Company issued an additional $500.0 principal value of 5.50% senior notes. The additional 5.50% senior notes were issued at a price of 103.5% of par value, and the Company received $514.0 after incurring investment banking and other fees and expenses of $3.5, which were deferred and are being amortized to interest expense over the term of the 5.50% senior notes. The premium related to the additional 5.50% senior notes was recorded as an unamortized premium and is being amortized as a reduction to interest expense over the term of the 5.50% senior notes. Interest payments on the 5.50% senior notes 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 4.625% senior notes. On August 14, 2020, the Company issued an additional $400.0 principal value of 4.625% senior notes. The additional 4.625% senior notes were issued at a price of 105.5% of 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 4.625% senior notes. The premium related to the additional 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 4.625% senior notes. Interest payments on the 4.625% senior notes are due semi-annually each April 15 and October 15. On March 10, 2021, th e Company issued $1,800.0 principal value of 4.50% senior notes maturing i n September 2 031. The 4.50% senior n otes were issued at par, and the Company receive d $1,783.2 after incurring investment banking and other fees and expenses of $16.8, which were d eferred and are being amortized to interest expense over the term of the 4.50% senior notes. Interest payments on the 4.50% senior notes are du e semi-annually each March 15 and September 15. With the net proceeds received from the issuance, the Company redeemed the outstanding principal balance of the Company’s previously held 5.00% senior notes maturing in August 2026. For additional information, see “Repayments of Debt” below. 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 and subsidiaries the Company designated as unrestricted subsidiaries, which such unrestricted subsidiaries includes 8th Avenue and its subsidiaries. These guarantees are subject to release in certain circumstances.
Long-Term Debt - Credit Agreement	Credit Agreement On March 18, 2020, the Company entered into a second amended and restated credit agreement (a s amended, including by the First Joinder Agreement, the Second Joinder Agreement, the Third Joinder Agreement and the Fourth Joinder Agreement (as defined below), restated or amended and restated, the “Credit Agreement”). The 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 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 initial Credit Agreement, which were deferred and are being amortized to interest expense over the term of the Credit Agreement. As of both September 30, 2023 and 2022 , t he Revolving Credit Facility had outstanding letters of credit of $19.7 , which reduced the available borrowing capacity under the Revolving Credit Facility to $730.3 . Any outstanding amounts under the Revolving Credit Facility must be repaid on or before March 18, 2025. The 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 specified in the Credit Agreement. The 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 Credit Agreement. The Company’s obligations under the Credit Agreement are unconditionally guaranteed by its existing and subsequently acquired or organized domestic subsidiaries (other than immaterial subsidiaries, certain excluded subsidiaries and subsidiaries the Company designates as unrestricted subsidiaries, which include 8th Avenue 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. On September 3, 2021, the Company entered into an amendment to the Credit Agreement to change the reference interest rate applicable to revolving loan borrowings in Pounds Sterling from a Eurodollar rate-based rate to a rate based on the Sterling Overnight Index Average. On December 17, 2021, the Company entered into a second amendment to the Credit Agreement to, among other provisions, facilitate the BellRing Spin-off. The amendment also amended the Credit Agreement to change the reference interest rate applicable to revolving loan borrowings in U.S. Dollars from the London Interbank Offered Rate (“LIBOR”) to a rate based on the adjusted term SOFR rate (as defined in the Credit Agreement). During the y ear ended September 30, 2022, the Company paid $0.4 of deferred financing fees in connection with the amendment. Borrowings in U.S. Dollars under the Revolving Credit Facility bear interest, at the option of the Company, at an annual rate equal to either (a) the adjusted term SOFR 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 adjusted term SOFR rate plus 1.00% per annum, in each case plus an applicable margin, which is determined by reference to the secured net leverage ratio (as defined in the Credit Agreement), with the applicable margin for adjusted term SOFR 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 accrue at a rate of 0.375% if the Company’s secured net leverage ratio is greater than 3.00:1.00, and 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 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 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 Credit Agreement may accelerate and the agent and lenders under the 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 Credit Agreement.
Long-Term Debt - Term Loan	Fourth Incremental Term Loan On April 26, 2023, the Company entered into a Joinder Agreement No. 4 (the “Fourth Joinder Agreement”) by and among the Company, as borrower, certain of the Company’s subsidiaries, as guarantors, the institutions party to the Fourth Joinder Agreement as lenders (the “Fourth Incremental Term Loan Lenders”) and Barclays Bank PLC, as the administrative agent. The Fourth Joinder Agreement provided for an incremental term loan (the “Fourth Incremental Term Loan”) of $400.0 under the Credit Agreement, which the Company borrowed in full on April 26, 2023. The Company incurred $1.9 of debt issuance costs in connection with the Fourth Incremental Term Loan, which were deferred and are being amortized to interest expense over the term of the Fourth Incremental Term Loan. Interest on the Fourth Incremental Term Loan accrues, at the Company’s option, at the base rate (as defined in the Credit Agreement) plus 1.25% per annum or the adjusted term SOFR rate plus 2.25% per annum. Interest is payable quarterly for loans bearing interest based upon the base rate and either monthly or every three months (depending on the applicable interest period) for loans bearing interest based upon the adjusted term SOFR rate. As of September 30, 2023, t he interest rate on the Fourth Incremental Term Loan was 7.67%. The maturity date for the Fourth Incremental Term Loan is April 26, 2026. The Company may prepay the Fourth Incremental Term Loan in whole or in part, without premium or penalty (subject to reimbursement of the Fourth Incremental Term Loan Lenders’ breakage costs under certain circumstances). The Fourth Joinder Agreement also contains mandatory prepayment provisions, including provisions for prepayment (a) from the net cash proceeds of certain debt incurrences, (b) of consolidated excess cash flow (as defined in the Credit Agreement) with certain adjustments for fiscal years beginning with the fiscal year ending September 30, 2024, which percentage shall be 50%, 25% or 0% depending on the Company’s secured net leverage ratio (as defined in the Credit Agreement) at the end of such fiscal year and (c) from the net cash proceeds of certain asset dispositions in excess of a specified threshold to the extent that the Company has not reinvested such proceeds in its business within a period of time described in the Fourth Joinder Agreement. The mandatory prepayments also are subject to certain adjustments and credits described in the Fourth Joinder Agreement.
Long-Term Debt - Muni Bond	Municipal Bond In connection with the construction of a filtration system at the Company’s potato plant in Chaska, Minnesota, the Company incurred debt that guarantees the repayment of certain industrial revenue bonds used to finance the construction of the project. 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.
Long-Term Debt - Repayments & Other	Repayments of Debt On June 27, 2022, the Company commenced a modified “Dutch Auction” tender offer to purchase up to $450.0 in aggregate cash consideration (excluding accrued interest) of its (i) 4.625% senior notes at a bid range of 81% to 88% of par and (ii) 4.50% senior notes at a bid range of 80% to 87% of par (collectively, the “Tender Offer”). The Tender Offer included a tender premium of 5% of par for holders who tendered their senior notes prior to 5:00 p.m., New York City time, on July 11, 2022 (the “Tender Premium”). On July 26, 2022, the Company settled the Tender Offer and purchased $139.8 in aggregate principal amount, or approximately 8%, of its outstanding 4.625% senior notes at 87% of par, including the Tender Premium, and $381.8 in aggregate principal amount, or approximately 22%, of its outstanding 4.50% senior notes at 86% of par, including the Tender Premium, for aggregate cash consideration of $450.0, excluding accrued interest and fees. The Company paid tender fees of $1.7 in connection with the Tender Offer, which were included in “(Gain) loss on extinguishment of debt, net” in the Consolidated Statements of Operations for the year ended September 30, 2022. The following table presents the Company’s (i) principal repayments of debt, which, net of discounts, were included in the Consolidated Statements of Cash Flows, (ii) principal amounts of debt exchanged (refer to “Debt Transactions in Connection with BellRing” above), which were not included in the Consolidated Statements of Cash Flows and (iii) the associated (gain) loss related to such repayments and exchanges included in “(Gain) loss on extinguishment of debt, net” in the Consolidated Statements of Operations. (Gain) Loss on Extinguishment of Debt, net Debt Instrument Principal Amount Repaid Principal Amount Exchanged Debt Discounts (Received) / Premiums Paid Write-off of Debt Issuance Costs / Write-off of Unamortized Premiums Year Ended September 30, 2023 4.50% senior notes $ 220.8 $ — $ (31.5) $ 1.7 $ — 4.625% senior notes 96.8 — (11.4) 0.5 (0.9) 5.625% senior notes 1.0 — — — — Third Incremental Term Loan 30.1 99.9 — 1.1 — Municipal bond 1.1 — — — — Total $ 349.8 $ 99.9 $ (42.9) $ 3.3 $ (0.9) Year Ended September 30, 2022 4.50% senior notes $ 529.5 $ — $ (74.7) $ 6.0 $ — 4.625% senior notes 167.8 — (21.9) 1.1 (1.8) 5.50% senior notes 15.0 — (1.2) 0.1 (0.2) 5.75% senior notes 840.0 — 24.1 5.0 (13.3) First Incremental Term Loan — 840.0 — 3.5 — Second Incremental Term Loan 107.7 342.3 — 0.7 — Municipal bond 1.1 — — — — Total $ 1,661.1 $ 1,182.3 $ (73.7) $ 16.4 $ (15.3) Year Ended September 30, 2021 5.00% senior notes $ 1,697.3 $ — $ 74.3 $ 18.9 $ — Municipal bond 1.0 — — — — Total $ 1,698.3 $ — $ 74.3 $ 18.9 $ — As of September 30, 2023, expected principal payments on the Company’s debt for the next five fiscal years were: Fiscal 2024 $ 1.1 Fiscal 2025 1.2 Fiscal 2026 401.2 Fiscal 2027 (a) 1,035.6 Fiscal 2028 940.4 (a) Includes principal payments of $575.0 related to the Company’s 2.50% convertible senior notes. Estimated future interest payments on the Company’s debt through fiscal 2028 are expected to be $1,367.1 (with $305.9 expected in fiscal 2024) based on interest rates as of September 30, 2023. Debt Covenants Under the terms of the Credit Agreement, the Company is required to comply with a financial covenant consisting of a secured net leverage ratio (as defined in the Credit Agreement) not to exceed 4.25:1.00, 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 Credit Agreement) exceeds 30% of the Company’s revolving credit commitments. In addition to the foregoing, under the terms of the Fourth Joinder Agreement, so long as any principal or accrued interest remains outstanding with respect to the Fourth Incremental Term Loan, the Company is required to comply with financial covenants consisting of the foregoing secured net leverage ratio as of the last day of each fiscal quarter and a minimum consolidated interest coverage ratio (as defined in the Credit Agreement) of not less than 2.00 to 1.00 measured as of the last day of each fiscal quarter. As of September 30, 2023, the Company was in compliance with these financial covenants. The 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 Credit Agreement.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2023
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 (the “opt-out plaintiffs”); and (iii) indirect purchasers of shell eggs (the “indirect purchaser plaintiffs”). Resolution of this matter : (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; (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; and (v) in September 2022, MFI settled the remaining pending claims for this matter, which had sought damages based on purchases of egg products by three opt-out plaintiffs, on confidential terms. MFI has at all times denied liability in this matter, and no settlement contains any admission of liability by MFI. During the year ended September 30, 2022, the Company expensed $13.8 related to the September 2022 settlement, which was included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. No expense was recorded in the years ended September 30, 2023 or 2021 related to these matters and the Company had no accruals related to these matters as of September 30, 2023 or 2022. 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 U.S. federal income tax purposes. 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 Farms, Inc. (“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 2018, but have subsequently been adjusted to apply only to 130 properties. 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 terms of the leases subsequent to September 30, 2023, 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 $13.1 and will increase up to 1.5% annually based on indexed inflation. The lease terms for the majority of the leases extend for approximately 14 years from September 30, 2023, and the Guarantees would remain in effect in the event the leases are extended for a renewal

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	12 Months Ended
	Sep. 30, 2023
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 accrual is 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, the plans are closed to new entrants and the benefit accrual is frozen with respect to existing 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, 2023 and a statement of the funded status and amounts recognized on the Consolidated Balance Sheets as of September 30, 2023 and 2022. North America Other International As of and for the Year Ended September 30, As of and for the Year Ended September 30, 2023 2022 2023 2022 Change in benefit obligation Benefit obligation at beginning of year $ 95.5 $ 133.3 $ 421.1 $ 821.3 Service cost 2.2 4.3 — — Interest cost 5.3 3.5 23.3 15.7 Plan participants’ contributions 0.3 0.4 — — Net actuarial gain (5.4) (38.9) (37.5) (251.6) Benefits paid (5.4) (5.9) (25.9) (28.4) Currency translation 0.1 (1.2) 41.0 (135.9) Benefit obligation at end of year $ 92.6 $ 95.5 $ 422.0 $ 421.1 Change in fair value of plan assets Fair value of plan assets at beginning of year $ 102.9 $ 136.6 $ 507.3 $ 970.9 Actual return on plan assets 10.1 (27.1) (14.3) (273.0) Employer contributions 0.1 0.4 — — Plan participants’ contributions 0.3 0.4 — — Benefits paid (5.4) (5.9) (25.9) (28.4) Currency translation 0.2 (1.5) 49.4 (162.1) Other — — (0.1) (0.1) Fair value of plan assets at end of year 108.2 102.9 516.4 507.3 Funded status $ 15.6 $ 7.4 $ 94.4 $ 86.2 Amounts recognized in assets or liabilities Other assets $ 15.9 $ 7.7 $ 94.4 $ 86.2 Other liabilities (0.3) (0.3) — — Net amount recognized $ 15.6 $ 7.4 $ 94.4 $ 86.2 Amounts recognized in accumulated OCI Net actuarial (gain) loss $ (2.7) $ 5.0 $ 47.7 $ 40.2 Prior service cost 0.4 0.6 10.3 10.7 Total $ (2.3) $ 5.6 $ 58.0 $ 50.9 Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 6.06 % 5.65 % n/a n/a Discount rate — Canadian plans 5.68 % 5.12 % n/a n/a Discount rate — Other international plans n/a n/a 5.67 % 5.15 % 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 3.02 % 3.85 % The fair value of plan assets for the North America and Other International pension plans exceeded the accumulated benefit obligation at September 30, 2023 and 2022. The aggregate accumulated benefit obligation for the North America pension plans was $91.8 and $94.6 at September 30, 2023 and 2022, respectively. The aggregate accumulated benefit obligation for the Other International pension plans was $422.0 and $418.9 at September 30, 2023 and 2022, respectively. The following tables present the components of net periodic benefit (income) cost for the pension plans including amounts recognized in OCI. Service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit (income) cost were reported in “Other income, net” in the Consolidated Statements of Operations. North America Year Ended September 30, 2023 2022 2021 Components of net periodic benefit (income) cost Service cost $ 2.2 $ 4.3 $ 3.9 Interest cost 5.3 3.5 3.2 Expected return on plan assets (7.5) (7.0) (6.4) Recognized net actuarial (gain) loss (0.2) 1.6 2.4 Recognized prior service cost 0.1 0.1 0.1 Net periodic benefit (income) cost $ (0.1) $ 2.5 $ 3.2 Weighted-average assumptions used to determine net benefit (income) cost Discount rate — U.S. plans 5.65 % 3.05 % 3.01 % Discount rate — Canadian plans 5.12 % 3.32 % 2.71 % Rate of compensation increase — U.S. plans 3.00 % 3.00 % 3.00 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Expected return on plan assets — U.S. plans 6.50 % 5.75 % 5.40 % Expected return on plan assets — Canadian plans 5.75 % 5.25 % 5.25 % Changes in plan assets and benefit obligation recognized in OCI Net gain $ (8.0) $ (4.7) $ (14.5) Recognized gain (loss) 0.2 (1.6) (2.4) Prior service cost (a) — — 0.5 Recognized prior service cost (0.1) (0.1) (0.1) Total recognized in OCI (before tax effects) $ (7.9) $ (6.4) $ (16.5) (a) Amounts reported for the year ended September 30, 2021 represent the impact of fiscal 2020 union negotiations that were ratified subsequent to September 30, 2020. Other International Year Ended September 30, 2023 2022 2021 Components of net periodic benefit income Interest cost $ 23.3 $ 15.7 $ 15.2 Expected return on plan assets (30.8) (24.8) (24.9) Recognized net actuarial loss 0.1 — — Recognized prior service cost 0.4 0.4 0.5 Net periodic benefit income $ (7.0) $ (8.7) $ (9.2) Weighted-average assumptions used to determine net benefit income Discount rate 5.15 % 2.05 % 1.73 % Rate of compensation increase 3.85 % 3.45 % 2.65 % Expected return on plan assets 5.63 % 2.73 % 2.38 % Changes in plan assets and benefit obligation recognized in OCI Net loss $ 7.6 $ 46.2 $ 26.4 Recognized loss (0.1) — — Recognized prior service cost (0.4) (0.4) (0.5) Total recognized in OCI (before tax effects) $ 7.1 $ 45.8 $ 25.9 The Company expects to make contributions of $0.3 and zero to its defined benefit North America and Other International pension plans, respectively, during fiscal 2024. The expected return on North America 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 57.7% equity securities, 38.0% fixed income and bonds, 3.3% real assets and 1.0% cash and cash equivalents. At September 30, 2023, equity securities were 64.7%, fixed income and bonds were 30.2%, real assets were 1.3% and cash and cash equivalents were 3.8% of the fair value of total plan assets, 96.8% of which was invested in passive index funds. At September 30, 2022, equity securities were 54.5%, fixed income and bonds were 33.9%, real assets were 2.9% and cash and cash equivalents were 8.7% of the fair value of total plan assets, 91.9% 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 71.6% fixed income and bonds, 27.7% liability driven investments, 0.6% real assets and 0.1% cash and cash equivalents. At September 30, 2023, fixed income and bonds were 75.2%, liability driven investments were 21.4% and cash and cash equivalents were 3.4% of the fair value of total plan assets, 23.7% of which was invested in passive index funds. At September 30, 2022, fixed income and bonds were 78.8%, liability driven investments were 18.7%, real assets were 0.4% and cash and cash equivalents were 2.1% of the fair value of total plan assets, 20.2% 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 America 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 NAV per share held by the plans at year end. North America September 30, 2023 September 30, 2022 Total Level 1 Level 2 Total Level 1 Level 2 Equities $ 11.9 $ — $ 11.9 $ 11.0 $ — $ 11.0 Fixed income and bonds 5.2 — 5.2 5.0 — 5.0 Cash and cash equivalents 4.1 4.1 — 8.9 8.9 — Fair value of plan assets in the fair value hierarchy 21.2 4.1 17.1 24.9 8.9 16.0 Equities 58.1 — — 45.1 — — Fixed income and bonds 27.6 — — 29.9 — — Real assets 1.3 — — 3.0 — — Investments measured at NAV (a) 87.0 — — 78.0 — — Total plan assets $ 108.2 $ 4.1 $ 17.1 $ 102.9 $ 8.9 $ 16.0 Other International September 30, 2023 September 30, 2022 Total Level 1 Level 2 Total Level 1 Level 2 Fixed income and bonds $ 280.4 $ 280.4 $ — $ 321.3 $ 321.3 $ — Liability driven instruments 91.6 91.6 — 77.9 77.9 — Cash and cash equivalents 17.4 17.4 — 10.6 10.6 — Fair value of plan assets in the fair value hierarchy 389.4 389.4 — 409.8 409.8 — Fixed income and bonds 107.8 — — 78.5 — — Liability driven instruments 19.2 — — 16.9 — — Real assets — — — 2.1 — — Investments measured at NAV (a) 127.0 — — 97.5 — — Total plan assets $ 516.4 $ 389.4 $ — $ 507.3 $ 409.8 $ — (a) In accordance with ASC Topic 820, certain investments were measured at NAV. In cases where the fair value was measured at NAV using the practical expedient provided for in ASC Topic 820, 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 America other postretirement benefit obligations over the two year period ended September 30, 2023 and a statement of the funded status and amounts recognized on the Consolidated Balance Sheets as of September 30, 2023 and 2022. Besides the North America plans, the Company does not maintain any other postretirement benefit plans. As of and for the Year Ended September 30, 2023 2022 Change in benefit obligation Benefit obligation at beginning of year $ 48.3 $ 66.5 Service cost 0.3 0.5 Interest cost 2.5 1.5 Net actuarial gain (3.0) (17.4) Benefits paid (2.3) (2.3) Currency translation — (0.5) Benefit obligation at end of year $ 45.8 $ 48.3 Change in fair value of plan assets Employer contributions 2.3 2.3 Benefits paid (2.3) (2.3) Fair value of plan assets at end of year — — Funded status $ (45.8) $ (48.3) Amounts recognized in assets or liabilities Other current liabilities (3.3) (3.0) Other liabilities (42.5) (45.3) Net amount recognized $ (45.8) $ (48.3) Amounts recognized in accumulated OCI Net actuarial loss $ (11.7) $ (9.2) Prior service credit (0.7) (5.4) Total $ (12.4) $ (14.6) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 6.01 % 5.62 % Discount rate — Canadian plans 5.67 % 5.12 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % The following table presents the components of net periodic benefit income for the other postretirement benefit plans including amounts recognized in OCI. Service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit income were reported in “Other income, net” in the Consolidated Statements of Operations. Year Ended September 30, 2023 2022 2021 Components of net periodic benefit income Service cost $ 0.3 $ 0.5 $ 0.5 Interest cost 2.5 1.5 1.5 Recognized net actuarial (gain) loss (0.5) 0.6 1.1 Recognized prior service credit (4.7) (4.6) (4.7) Net periodic benefit income $ (2.4) $ (2.0) $ (1.6) Weighted-average assumptions used to determine net benefit income Discount rate — U.S. plans 5.62 % 2.89 % 2.79 % Discount rate — Canadian plans 5.12 % 3.45 % 2.78 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Changes in benefit obligation recognized in OCI Net gain $ (3.0) $ (17.5) $ (4.3) Recognized net actuarial gain (loss) 0.5 (0.6) (1.1) Recognized prior service credit 4.7 4.6 4.7 Total recognized in OCI (before tax effects) $ 2.2 $ (13.5) $ (0.7) For September 30, 2023 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to domestic plans for fiscal 2024 was 6.5% for participants both under the age of 65 and over the age of 65, declining gradually to an ultimate rate of 5.0% for fiscal 2030 and beyond. For September 30, 2022 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to domestic plans for fiscal 2023 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 fiscal 2028 and beyond. For both September 30, 2023 and 2022 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 4.5%, and will remain at this rate for 2024 and beyond . Additional Information As of September 30, 2023, expected future benefit payments and related federal subsidy receipts (Medicare Part D) in the next ten fiscal years were: Pension Benefits Other Benefits Subsidy Receipts Fiscal 2024 $ 26.7 $ 3.5 $ 0.1 Fiscal 2025 27.6 3.5 0.1 Fiscal 2026 28.9 3.5 0.1 Fiscal 2027 30.1 3.5 0.2 Fiscal 2028 30.7 3.5 0.2 Fiscal 2029 - 2033 172.2 17.8 1.1

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION Long-Term Incentive Plans The Company’s employees participate in various Company long-term incentive plans (the “Long-Term Incentive Plans”). On January 27, 2022, the Company’s shareholders approved the 2021 Long-Term Incentive Plan (the “2021 Plan”), which permits the issuance of stock-based compensation awards of up to 2.4 million shares, plus shares remaining to be issued under the 2019 Long-Term Incentive Plan (including any shares assumed thereunder from the 2016 and 2012 Long-Term Incentive Plans) which were transferred to the 2021 Plan upon its effectiveness as well as shares underlying awards previously issued under any of the Long-Term Incentive Plans which awards are later forfeited. Awards issued under the Long-Term Incentive Plans have a maximum term of 10 years. Total compensation cost for the Company’s cash and non-cash stock-based compensation awards recognized in the years ended September 30, 2023, 2022 and 2021 was $77.8, $66.4 and $49.7, respectively, and the related recognized deferred tax benefit for each of those periods was approximately $10.5, $9.1 and $5.8, respectively. As of September 30, 2023, the total compensation cost related to Post’s non-vested awards not yet recognized was $77.2, which is expected to be recognized over a weighted-average period of 1.3 years. BellRing Spin-off In connection with the BellRing Spin-off, adjustments were made to the terms of outstanding equity-based awards (the “Equity Awards”) to preserve the intrinsic value of the Equity Awards and to participants’ accounts under the deferred compensation plans maintained by the Company with respect to notional investments in Post common stock (the “Deferred Compensation Accounts”). The adjustments to the Equity Awards and Deferred Compensation Accounts were based on the volume weighted average price of a share of Post common stock during the five trading day period prior to and including March 10, 2022 and the volume weighted average price of a share of Post common stock during the five trading day period immediately following March 10, 2022. The adjustments to the Equity Awards and Deferred Compensation Accounts had an immaterial impact on the Company’s Consolidated Statements of Operations for the years ended September 30, 2023 and 2022. Stock Appreciation Rights (“SARs”) $ in millions, except price per share SARs Weighted- Average Exercise Price Per Share Weighted- Aggregate Outstanding at September 30, 2022 81,554 $ 33.42 Granted — Exercised (29,656) 28.28 Forfeited — Expired — Outstanding at September 30, 2023 51,898 36.35 1.23 $ 2.6 Vested and expected to vest as of September 30, 2023 51,898 36.35 1.23 2.6 Exercisable at September 30, 2023 51,898 36.35 1.23 2.6 Upon exercise of each SAR, 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 SARs exercised was $1.9, $3.0 and $3.2 during the years ended September 30, 2023, 2022 and 2021, respectively. There were no SARs granted during the years ended September 30, 2023, 2022 or 2021. Stock Options $ in millions, except price per share Stock Options Weighted- Average Exercise Price Per Share Weighted- Aggregate Outstanding at September 30, 2022 1,011,315 $ 48.75 Granted — — Exercised (262,607) 39.57 Forfeited — — Expired — — Outstanding at September 30, 2023 748,708 51.96 3.63 $ 25.3 Vested and expected to vest as of September 30, 2023 748,708 51.96 3.63 25.3 Exercisable at September 30, 2023 748,708 51.96 3.63 25.3 The fair value of each stock option was estimated on the grant date using the Black-Scholes Model. The Company used the simplified method for estimating a stock option term as it did not have sufficient historical stock option exercise experience upon which to estimate an expected term. The expected term was estimated based on the award’s vesting period and contractual term. Expected volatilities were based on historical volatility trends and other factors. The risk-free rate was the interpolated U.S. Treasury rate for a term equal to the expected term. There were no stock options granted during the years ended September 30, 2023, 2022 or 2021. The total intrinsic value of stock options exercised was $14.1, $14.1 and $46.4 in the years ended September 30, 2023, 2022 and 2021, respectively. The Company received proceeds from the exercise of stock options of $3.9, $4.9 and $7.6 during the years ended September 30, 2023, 2022 and 2021, respectively. Restricted Stock Units (“RSUs”) RSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 1,348,806 $ 68.38 Granted 526,035 90.85 Vested (763,124) 67.34 Forfeited (51,485) 74.06 Nonvested at September 30, 2023 1,060,232 79.99 The grant date fair value of each 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 RSUs was $79.99, $68.38 and $97.23 at September 30, 2023, 2022 and 2021, respectively. The total vest date fair value of RSUs that vested during fiscal 2023, 2022 and 2021 was $68.9, $35.1 and $49.8, respectively. Cash-Settled Restricted Stock Units (“Cash RSUs”) Cash RSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 29,063 $ 34.68 Granted — — Vested (16,015) 34.68 Forfeited — — Nonvested at September 30, 2023 13,048 34.68 At September 30, 2023, the 13,048 nonvested Cash RSUs were valued at the greater of the Company’s closing stock price or the grant price of $34.68. Cash used by the Company to settle Cash RSUs was $1.4, $1.1 and $1.1 for the years ended September 30, 2023, 2022 and 2021, respectively. Earnings-Based Performance Restricted Stock Units (“Earnings PRSUs”) Earnings PRSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 272,427 $ 70.46 Granted 142,939 94.09 Vested (148,531) 70.36 Forfeited (7,293) 83.83 Nonvested at September 30, 2023 259,542 83.20 During the years ended September 30, 2023, 2022 and 2021, the Company granted Earnings PRSUs to certain employees. These awards will be earned based on reaching certain earnings-based targets over a period ranging from one to three years. The grant date fair value of each Earnings PRSU award was determined based upon the closing price of the Company’s common stock on the date of grant and the assumption that the Company would meet the full earnings-based targets. The Company reassesses the probability of achieving the earnings-based targets each quarterly reporting period and adjusts compensation cost accordingly. The weighted-average grant date fair value of nonvested Earnings PRSUs was $83.20, $70.46 and $98.33 at September 30, 2023, 2022 and 2021, respectively. The total vest date fair value of Earnings PRSUs that vested during the year ended September 30, 2023 was $14.1. No Earnings PRSUs vested during the years ended September 30, 2022 or 2021. Market-Based Performance Restricted Stock Units (“Market PRSUs”) Market PRSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 374,402 $ 106.10 Granted 142,843 156.05 Vested — — Forfeited (23,140) 102.95 Nonvested at September 30, 2023 494,105 120.69 The total vest date fair value of Market PRSUs that vested during fiscal 2022 and 2021 was $6.6 and $3.9, respectively. No Market PRSUs vested during the year ended September 30, 2023. During the years ended September 30, 2023, 2022 and 2021, the Company granted Market PRSUs to certain employees, which 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 a Market PRSU grant may earn a total award ranging from 0% to 260% of the target award. The fair value of each Market PRSU was estimated on the grant date using a Monte Carlo simulation. The weighted-average assumptions for Market PRSUs granted during the years ended September 30, 2023, 2022 and 2021 are summarized in the table below. 2023 2022 2021 Expected term (in years) 3.0 3.0 3.0 Expected stock price volatility 29.1% 27.7% 28.3% Risk-free interest rate 4.1% 0.9% 0.2% Expected dividends 0% 0% 0% Fair value (per Market PRSU) $156.05 $163.63 $152.58 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, and, 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 and director 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 the Equity Option. Deferrals into the Equity Option are generally distributed in Post common 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 regarding deferred compensation, see Note 14.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Sep. 30, 2023
Equity, Attributable to Parent [Abstract]
Shareholders' Equity	SHAREHOLDERS’ EQUITY The following table summarizes the Company’s repurchases of its common stock. Year Ended September 30, 2023 2022 2021 Shares repurchased (in millions) 4.4 4.9 4.0 Average price per share (a) $ 87.13 $ 90.02 $ 98.37 Total share repurchase costs (b) $ 387.1 $ 439.0 $ 393.7 (a) Average price per share excludes broker’s commissions, which are included in “Total share repurchase costs” within this table. Average price per share during the year ended September 30, 2022 was $103.79 prior to the BellRing Spin-off and $81.53 subsequent to the BellRing Spin-off. (b) “Purchases of treasury stock” in the Consolidated Statements of Cash Flows for the year ended September 30, 2022 included $4.0 of repurchases of common stock that were accrued in fiscal 2021 but did not settle until fiscal 2022. “Purchases of treasury stock” in the Consolidated Statements of Cash Flows for the year ended September 30, 2021 included $7.4 of repurchases of common stock that were accrued in fiscal 2020 but did not settle until fiscal 2021. On April 28, 2023, the Company completed the Pet Food acquisition (see Note 6). The purchase price included the issuance of 5.4 million shares of Post common stock to Smucker. The shares of Post common stock were valued based on the price of Post’s common stock for total stock consideration of $492.3. The Company did not receive any cash proceeds from the issuance of the shares of Post common stock to Smucker. 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. The Company settled a structured share repurchase arrangement during the year ended September 30, 2021 and received cash payments of $47.5, which were recorded as “Cash received from share repurchase contracts” in the Consolidated Statements of Cash Flows for the year ended September 30, 2021.

Segments

Segments	12 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Segments	SEGMENTS At September 30, 2023, the Company managed and reported operating results through the following four reportable segments: • Post Consumer Brands: North American RTE cereal, pet food and nut butters; • Weetabix: primarily U.K. RTE cereal, muesli and protein-based shakes; • Foodservice: primarily egg and potato products; and • Refrigerated Retail: primarily side dish, egg, cheese and sausage products. 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. Amounts reported for Corporate in the table below include any amounts attributable to PHPC prior to the PHPC Redemption (see Note 5). Management evaluates each segment’s performance based on its segment profit, which for all segments is its earnings/loss 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 sale of businesses and facilities, gain on/adjustment to bargain purchase, interest expense and other unallocated corporate income and expenses. In fiscal 2023, 2022 and 2021, Post’s revenues were primarily generated by sales within the U.S.; foreign sales were 11.0%, 12.5% and 14.3% of total net sales, respectively. The largest concentration of foreign sales was within the U.K., which accounted for 54.0%, 52.9% and 54.6% of total foreign sales in fiscal 2023, 2022 and 2021, respectively. Sales are attributed to individual countries based on the address to which the product is shipped. As of September 30, 2023 and 2022, 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 $280.9 and $253.6, respectively. In the years ended September 30, 2023, 2022 and 2021, one customer, including its affiliates, accounted for 17.3%, 14.4% and 15.9%, respectively, of Post’s 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. Note that additions to property and intangibles exclude additions through business acquisitions (see Note 6). Year Ended September 30, 2023 2022 2021 Net Sales Post Consumer Brands $ 3,033.1 $ 2,242.7 $ 1,915.3 Weetabix 512.1 477.3 477.5 Foodservice 2,425.9 2,095.0 1,615.6 Refrigerated Retail 1,019.7 1,036.6 974.5 Eliminations and Corporate 0.2 (0.4) (2.2) Total $ 6,991.0 $ 5,851.2 $ 4,980.7 Segment Profit Post Consumer Brands $ 378.8 $ 314.6 $ 316.6 Weetabix 73.9 109.5 115.4 Foodservice 349.5 151.0 61.7 Refrigerated Retail 69.2 57.1 75.9 Total segment profit 871.4 632.2 569.6 General corporate expenses and other 222.7 196.8 52.6 Impairment of goodwill 42.2 — — Interest expense, net 279.1 317.8 332.6 (Gain) loss on extinguishment of debt, net (40.5) (72.6) 93.2 Income on swaps, net (39.9) (268.0) (122.8) Gain on investment in BellRing (5.1) (437.1) — Earnings before income taxes and equity method loss $ 412.9 $ 895.3 $ 214.0 Net sales by product Cereal $ 2,730.8 $ 2,595.0 $ 2,333.3 Eggs and egg products 2,304.0 2,026.1 1,556.1 Side dishes (including potato products) 732.0 652.4 575.0 Pet food 679.8 — — Cheese and dairy 191.5 214.3 223.0 Sausage 163.6 171.2 165.9 Nut butters 100.5 111.7 58.7 Protein-based products 34.1 12.9 — Other 55.4 68.5 70.9 Eliminations (0.7) (0.9) (2.2) Total $ 6,991.0 $ 5,851.2 $ 4,980.7 Additions to property and intangibles Post Consumer Brands $ 112.8 $ 91.2 $ 81.2 Weetabix 30.1 26.7 19.6 Foodservice and Refrigerated Retail 144.0 136.1 89.7 Corporate (a) 24.2 20.8 0.4 Total $ 311.1 $ 274.8 $ 190.9 Depreciation and amortization Post Consumer Brands $ 157.3 $ 133.1 $ 122.0 Weetabix 35.9 37.5 39.0 Foodservice 128.7 127.5 126.0 Refrigerated Retail 76.1 78.4 75.5 Total segment depreciation and amortization 398.0 376.5 362.5 Corporate 9.1 3.7 4.0 Total $ 407.1 $ 380.2 $ 366.5 September 30, 2023 2022 Assets Post Consumer Brands $ 4,782.2 $ 3,529.1 Weetabix 1,737.8 1,591.3 Foodservice and Refrigerated Retail 4,921.6 5,022.7 Corporate 205.1 1,164.9 Total assets $ 11,646.7 $ 11,308.0 (a) During the years ended September 30, 2023 and 2022, the Company had non-cash exchanges of fixed assets of $8.1 and $19.5, respectively, which were included in the Corporate additions to property and intangibles.

Subsequent Events

Subsequent Events	12 Months Ended
	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTSOn October 7, 2023, the Company entered into a definitive agreement to acquire substantially all of the assets of Perfection Pet Foods, LLC (“Perfection”) for $235.0, subject to working capital adjustments. Perfection is a manufacturer and packager of private label and co-manufactured pet food and baked treat products. The acquisition is expected to close in Post’s first quarter of fiscal 2024. Upon closing, the financial results of Perfection are expected to be reported in the Post Consumer Brands segment.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Pay vs Performance Disclosure
Net Earnings	$ 301.3	$ 756.6	$ 166.7

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		OTHER INFORMATION Rule 10b5-1 and Non-Rule 10b5-1 Trading Arrangements During the three months ended September 30, 2023, no director or “officer,” as defined in Rule 16a-1(f) under the Exchange Act, of the Company adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Regulation S-K.
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation — The consolidated financial statements include the operations of Post and its 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, allowance for trade promotions, business combinations, pension and benefit plan assumptions, valuation assumptions of goodwill and other intangible assets and income taxes. Actual results could differ from those estimates.
Business Combinations	Business Combinations — The Company uses the acquisition method of accounting for acquired businesses. Under the acquisition method, the Company’s financial statements reflect the operations of an acquired business starting from the date of acquisition. The assets acquired and liabilities assumed are recorded at their respective estimated fair values at the date of the acquisition. Useful lives of identified tangible and intangible assets are determined based on the expected time period in which the cash flows of the related assets are expected to be realized. 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 acquired over the purchase price is recorded as a gain on bargain purchase. The Company utilizes various valuation methodologies (and depending on the size and complexity of an acquisition, assistance from third-party specialists) to estimate the fair value of assets acquired and liabilities assumed based on the nature of the underlying asset or liability. These methodologies include but are not limited to utilizing replacement cost, comparative sales and market- and income-based approaches. The income approach utilizes significant unobservable inputs, including revenue growth rates, discount rates, attrition rates and royalty rates. These fair value measurements fall within Level 3 of the
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 cash deposits which serve as collateral for certain commodity and energy hedging contracts as well as the Company’s high deductible workers’ compensation insurance program.
Receivables	Receivables — Receivables are reported net of appropriate allowances for credit losses, cash discounts and other amounts which the Company does not ultimately expect to collect. To calculate an allowance for credit losses, the Company estimates uncollectible amounts based on a review of past due balances, historical loss information and expectations regarding potential future losses. 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. As of September 30, 2023 and 2022, the Company did not have off-balance sheet credit exposure related to its customers.
Inventories	Inventories — Inventories, other than flocks, are generally valued at the lower of cost (determined on a first-in, first-out basis) or net realizable value. Reported amounts have been reduced by an allowance for excess and 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 and related charges principally consist of one-time termination benefits, severance, contract termination benefits, accelerated stock compensation and other employee separation costs. 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.
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 30 years for machinery and equipment; 1 to 35 years for buildings, building improvements and leasehold improvements; and 1 to 7 years for software. Total depreciation expense was $245.3, $232.9 and $222.2 in fiscal 2023, 2022 and 2021, respectively. Any gains and losses incurred on the sale or disposal of assets are included in “Other operating expense (income), net” in the Consolidated Statements of Operations. Ordinary repair and maintenance costs are accounted for under the direct expensing method.
Goodwill	Goodwill is calculated as the excess of the purchase price of acquired businesses over the fair market value of their identifiable net assets and represents the value the Company expects to achieve through the implementation of operational synergies, the expansion of the business into new or growing segments of the industry and the addition of new employees. The Company conducts a goodwill impairment 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 assessment performed may be either qualitative or quantitative; however, 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 2023, 2022 and 2021, the Company performed a quantitative impairment test for all reporting units. The Company has six reporting units, which have been identified at either the operating segment level, or in the case of certain reporting units, at a level below the operating segment. The estimated fair value of each reporting unit 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 for comparable peers. These fair value measurements fall within Level 3 of the fair value hierarchy as described in Note 14.
Other Intangible Assets	Other Intangible Assets — Other intangible assets consist primarily of customer relationships, trademarks, brands and licensing agreements 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 and right-of-use (“ROU”) assets. Trademarks and brands 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 or brand may be impaired. The trademark and brand impairment test performed may either be qualitative or quantitative; however, if adverse qualitative trends are identified that could negatively impact the fair value of the trademark or brand, a quantitative impairment test is performed. In fiscal 2023, 2022 and 2021, the Company performed a quantitative impairment test. The quantitative trademark and brand impairment tests require the Company to compare the calculated fair value of the trademark or brand to its carrying value. If the carrying value of the intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. The fair value is determined using an income-based approach, 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 fiscal 2023, 2022 and 2021, the Company performed a quantitative impairment test for all indefinite-lived intangible assets and concluded for each year there were no impairments. The estimated fair value of all indefinite-lived trademarks exceeded book value by 11% or greater, 23% or greater and 22% or greater at September 30, 2023, 2022 and 2021, respectively . These fair value measurements fall within Level 3 of the fair value hierarchy as described in Note 14. In addition, definite-lived assets (groups) are tested for recoverability when events or changes in circumstances indicate that the carrying value of an asset (group) may not be recoverable or the estimated useful life is no longer appropriate. The Company groups assets at the lowest level for which cash flows are separately identifiable. In general, an asset (group) is deemed impaired and written down to its fair value if the estimated related undiscounted future cash flows are less than its carrying amount. There were no impairments recorded on the Company’s definite-lived assets (groups) in fiscal 2023, 2022 or 2021.
Internal Use Software, Policy	Software Implementation Costs — For hosting arrangements that are service contracts, the Company capitalizes certain implementation costs incurred during the development stage of the related project .
Deferred Compensation Investments	Deferred Compensation Investments — The Company funds a portion of its deferred compensation liability by investing in certain mutual funds in substantially 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 are stated at fair value in “Prepaid expenses and other current assets” and “Other assets” on the Consolidated Balance Sheets (see Note 14). Both realized and unrealized gains and losses on these assets are generally 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 purchases of raw materials and supplies, interest rate risks 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 may 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. Gains and losses on derivatives designated as cash flow hedges are recorded in other comprehensive income or loss (“OCI”) and are reclassified to the Consolidated Statements of Operations in conjunction with the recognition of the underlying hedged item. If a derivative is designated as a hedge of a net investment in a foreign operation, its changes in fair value are recorded in OCI and subsequently recognized in earnings when the foreign operation is liquidated. Changes in the fair value of derivatives that are not designated for hedge accounting are recognized immediately in the Consolidated Statements of Operations. The Company does not have any derivatives currently designated as hedging instruments under Accounting Standards Codification (“ASC”) Topic 815, “Derivatives and Hedging.” Cash flows associated with all derivatives are reported as cash flows from operating activities in the Consolidated Statements of Cash Flows, unless the derivative contains an other-than-insignificant financing element, in which case its cash flows are reported as cash flows from financing activities.
Leases	Leases — The Company leases office space, certain warehouses and equipment primarily through operating lease agreements. The Company has no material finance lease agreements. 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. For lease arrangements that 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 Sheets. 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 do not have a material impact on the Company’s financial statements.
Revenue	Revenue — 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.
Cost of Good Sold	Cost of Goods Sold —
Advertising Cost	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 the equity or liability award. For liability awards, the fair market value is remeasured at each quarterly reporting period. The cost for equity and liability awards is recognized ratably 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.
Income Tax (Benefit) Expense	Income Taxes — Income tax expense 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 established against the related deferred tax assets to the extent that it is more likely than not that the future benefits will not be realized. Reserves are recorded for estimated exposures associated with the Company’s tax filing positions, which are subject to periodic audits by governmental taxing authorities. Interest incurred due to an underpayment of income taxes is classified as income tax expense. The Company considers the undistributed earnings of its foreign subsidiaries to be permanently invested, so no United States (“U.S.”) taxes have been recorded in relation to the Company’s investment in its foreign subsidiaries.
Earnings Per Share	Earnings per Share — The Company has presented basic and diluted earnings per share for both continuing and discontinued operations. Basic earnings per share is based on the average number of shares of common stock outstanding during the year. 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 and restricted stock units using the “treasury stock” method and convertible senior notes using the “if-converted” method. Remeasurements to the redemption value of the redeemable noncontrolling interest (“NCI”) (see Note 5) were recognized as a deemed dividend. The Company made an election to treat the portion of the deemed dividend that exceeded fair value as an adjustment to income available to common shareholders for basic and diluted earnings from continuing operations per share. In

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Property	September 30, 2023 2022 Land and land improvements $ 109.9 $ 92.2 Buildings and leasehold improvements 1,042.9 932.7 Machinery and equipment 2,312.2 1,951.1 Software 113.3 110.6 Construction in progress 191.1 182.7 3,769.4 3,269.3 Accumulated depreciation (1,748.0) (1,517.4) $ 2,021.4 $ 1,751.9
Other intangible assets	September 30, 2023 September 30, 2022 Carrying Accum. Net Carrying Accum. Net Subject to amortization: Customer relationships $ 2,535.5 $ (940.7) $ 1,594.8 $ 2,129.7 $ (816.4) $ 1,313.3 Trademarks, brands and licensing agreements 885.8 (301.3) 584.5 647.7 (260.4) 387.3 3,421.3 (1,242.0) 2,179.3 2,777.4 (1,076.8) 1,700.6 Not subject to amortization: Trademarks and brands 1,033.1 — 1,033.1 1,011.6 — 1,011.6 $ 4,454.4 $ (1,242.0) $ 3,212.4 $ 3,789.0 $ (1,076.8) $ 2,712.2

Discontinued Operations and D_2

Discontinued Operations and Disposal Groups (Tables)	12 Months Ended
	Sep. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations, Net Assets	The following is a summary of BellRing’s net assets as of March 10, 2022. Total Assets $ 633.0 Less: Total Liabilities 1,064.6 BellRing Net Assets $ (431.6)
Net Earnings from Discontinued Operations	The following table presents the components of net earnings from discontinued operations. The year ended September 30, 2022 represents the period ending March 10, 2022, the completion date of the BellRing Spin-off. Year Ended September 30, 2022 2021 Net Sales $ 541.9 $ 1,246.0 Cost of goods sold 390.3 859.8 Gross Profit 151.6 386.2 Selling, general and administrative expenses 68.5 167.1 Amortization of intangible assets 8.7 51.2 Other operating income, net — (0.1) Operating Profit 74.4 168.0 Interest expense, net 13.1 43.2 Loss on extinguishment and refinancing of debt, net 17.6 1.6 Earnings from Discontinued Operations before Income Taxes 43.7 123.2 Income tax expense 10.3 28.4 Net Earnings from Discontinued Operations, Including Noncontrolling Interest 33.4 94.8 Less: Net earnings attributable to noncontrolling interest from discontinued operations 11.8 33.0 Net Earnings from Discontinued Operations, net of tax and noncontrolling interest $ 21.6 $ 61.8

Noncontrolling Interests, Equ_2

Noncontrolling Interests, Equity Interests and Related Party Transactions (Tables)	12 Months Ended
	Sep. 30, 2023
Equity Method Investments and Joint Ventures [Abstract]
Effects of changes in ownership of PHPC on Post equity	Year Ended September 30, 2023 2022 2021 PHPC IPO offering costs $ — $ — $ (16.9) Initial valuation of PHPC Warrants — — (16.9) Net earnings attributable to redeemable NCI 12.1 6.7 5.8 Redemption value adjustment (5.9) (1.6) — PHPC deemed dividend $ 6.2 $ 5.1 $ (28.0)
Redeemable Noncontrolling Interest	As of and for the Year Ended September 30, 2023 2022 2021 Balance, beginning of year $ 306.6 $ 305.0 $ — Impact of PHPC IPO (a) — — 271.2 Net earnings attributable to redeemable NCI 12.1 6.7 5.8 PHPC deemed dividend (6.2) (5.1) 28.0 Redemption of PHPC Series A Common Stock (312.5) — — Balance, end of year $ — $ 306.6 $ 305.0 (a) For the year ended September 30, 2021, the impact of the PHPC IPO included the value of PHPC Units owned by public stockholders of $305.0 less offering costs of $16.9 and the initial valuation of PHPC Warrants of $16.9.
Equity Method Loss Attributable to 8th Avenue	Net loss attributable to 8th Avenue common shareholders $ (60.6) 60.5 % Equity method loss attributable to Post $ (36.7) Less: Amortization of basis difference, net of tax (a) 6.8 Equity method loss, net of tax $ (43.5)
8th Avenue Summarized Financial Information	The following table presents summarized financial information of 8th Avenue prior to the discontinuance of applying the equity method to the investment. Year Ended September 30, 2022 2021 Net sales $ 1,089.0 $ 900.8 Gross profit $ 159.9 $ 132.3 Net loss $ (210.9) $ (24.3) Less: Preferred stock dividend 40.4 36.3 Net loss attributable to 8th Avenue common shareholders $ (251.3) $ (60.6)

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Sep. 30, 2023
Business Acquisition
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table presents the purchase price allocation, including immaterial measurement period adjustments, related to the Pet Food acquisition based upon the fair values of assets acquired and liabilities assumed as of September 30, 2023. Inventories $ 205.8 Prepaid expenses and other current assets 0.5 Property 192.9 Other intangible assets 626.0 Deferred tax asset 2.7 Other assets 0.3 Other current liabilities (14.7) Other liabilities (0.2) Total identifiable net assets 1,013.3 Goodwill 194.2 Fair value of total consideration transferred $ 1,207.5
Pro Forma Information	Year Ended September 30, 2023 2022 2021 Pro forma net sales $ 7,902.9 $ 7,360.2 $ 5,184.3 Pro forma net earnings from continuing operations $ 354.2 $ 607.0 $ 96.9 Pro forma basic earnings from continuing operations per common share $ 5.78 $ 9.15 $ 1.51 Pro forma diluted earnings from continuing operations per common share $ 5.36 $ 8.93 $ 1.48

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Carrying Amount of Goodwill	Post Consumer Brands Weetabix Foodservice Refrigerated Retail Total Balance, September 30, 2021 Goodwill (gross) $ 2,067.1 $ 929.4 $ 1,355.0 $ 807.9 $ 5,159.4 Accumulated impairment losses (609.1) — — (48.7) (657.8) Goodwill (net) $ 1,458.0 $ 929.4 $ 1,355.0 $ 759.2 $ 4,501.6 Goodwill from acquisitions (a) — 13.9 0.3 — 14.2 Sale of business (b) — — — (4.2) (4.2) Currency translation adjustment (0.3) (161.7) — — (162.0) Balance, September 30, 2022 Goodwill (gross) $ 2,066.8 $ 781.6 $ 1,355.3 $ 803.7 $ 5,007.4 Accumulated impairment losses (609.1) — — (48.7) (657.8) Goodwill (net) $ 1,457.7 $ 781.6 $ 1,355.3 $ 755.0 $ 4,349.6 Goodwill from acquisition 194.2 — — — 194.2 Impairment loss — — — (42.2) (42.2) Currency translation adjustment 0.1 72.7 — — 72.8 Balance, September 30, 2023 Goodwill (gross) $ 2,261.1 $ 854.3 $ 1,355.3 $ 803.7 $ 5,274.4 Accumulated impairment losses (609.1) — — (90.9) (700.0) Goodwill (net) $ 1,652.0 $ 854.3 $ 1,355.3 $ 712.8 $ 4,574.4 (a) In fiscal 2022, the Company recorded $13.9 of goodwill related to the Lacka Foods acquisition and also recorded a final measurement period adjustment of $0.3 related to the Almark acquisition. For additional information on the Company’s acquisitions, see Note 6. (b) In December 2021, the Company completed the WEF Transaction. For additional information on the WEF Transaction, see Note 7.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Reconciliation of expense (benefit) for Income Taxes	Year Ended September 30, 2023 2022 2021 Current: Federal $ 96.4 $ 71.1 $ (20.3) State 21.0 11.1 (0.2) Foreign 5.2 13.2 10.5 122.6 95.4 (10.0) Deferred: Federal (10.7) (9.7) 22.6 State (11.8) — 3.4 Foreign (0.4) — 42.2 (22.9) (9.7) 68.2 Income tax expense $ 99.7 $ 85.7 $ 58.2
Reconciliation of Income Tax expense (benefit)	Year Ended September 30, 2023 2022 2021 Computed tax at federal statutory rate (21%) $ 86.7 $ 188.0 $ 44.9 State income tax, net of effect on federal tax 12.2 10.3 1.7 Non-deductible goodwill impairment charge 8.9 — — Non-deductible compensation 7.0 5.9 5.4 Valuation allowances 1.0 1.4 2.9 Enacted tax law and changes in deferred tax rates (5.8) 0.9 40.0 Excess tax benefits for share-based payments (5.7) (3.6) (6.1) Income tax credits (2.4) (1.9) (1.5) Enhanced deduction for food donations (1.6) (1.0) (0.8) Gain on investment in BellRing (a) (1.1) (91.8) — Rate differential on foreign income (0.2) (10.2) (11.0) Return-to-provision and changes in prior year accruals (0.1) (0.5) (2.8) Net losses and basis difference attributable to equity method investment — (14.1) (9.2) Gain on bargain purchase — — (2.4) Other, net (none in excess of 5% of statutory tax) 0.8 2.3 (2.9) Income tax expense $ 99.7 $ 85.7 $ 58.2 (a) No income taxes have been recorded with respect to the non-cash realized and unrealized book gains on the Company’s Investment in BellRing during the years ended September 30, 2023 or 2022, as the Company fully divested its Investment in BellRing within 12 months of the BellRing Spin-off in a manner intended to qualify as tax-free for U.S. federal income tax purposes. For additional information on our Investment in BellRing, refer to Notes 4, 5 and 16.
Deferred tax assets (liabilities)	September 30, 2023 September 30, 2022 Assets Liabilities Net Assets Liabilities Net Disallowed interest carryforwards $ 53.9 $ — $ 53.9 $ 55.4 $ — $ 55.4 Lease liabilities 49.1 — 49.1 35.8 — 35.8 Derivatives, equity securities and investment adjustments 41.0 — 41.0 34.9 — 34.9 Net operating loss and credit carryforwards 20.9 — 20.9 24.1 — 24.1 Stock-based and deferred compensation 20.6 — 20.6 19.9 — 19.9 Inventory 16.0 — 16.0 8.8 — 8.8 Capitalized research and development 11.2 — 11.2 — — — Accrued liabilities 10.8 — 10.8 7.0 — 7.0 Accrued vacation, incentive and severance 10.3 — 10.3 6.2 — 6.2 Basis difference attributable to equity method investment 4.7 — 4.7 4.6 — 4.6 Intangible assets — (592.2) (592.2) — (611.4) (611.4) Property — (226.1) (226.1) — (197.6) (197.6) ROU assets — (46.2) (46.2) — (32.9) (32.9) Pension and other postretirement benefits — (16.2) (16.2) — (11.4) (11.4) Other items 6.9 (2.7) 4.2 5.5 (1.8) 3.7 Total gross deferred income taxes 245.4 (883.4) (638.0) 202.2 (855.1) (652.9) Valuation allowance (36.4) — (36.4) (35.5) — (35.5) Total deferred income taxes $ 209.0 $ (883.4) $ (674.4) $ 166.7 $ (855.1) $ (688.4)
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	As of and for the Year Ended September 30, 2023 2022 2021 Balance, beginning of year $ 11.7 $ 12.5 $ 8.3 Additions for tax positions taken in current year and acquisitions 0.8 0.1 0.3 Additions for tax positions taken in prior years 0.4 — 5.2 Settlements with tax authorities/statute expirations (0.1) (0.9) (1.3) Balance, end of year $ 12.8 $ 11.7 $ 12.5
Schedule of Income before Income Tax, Domestic and Foreign	Year Ended September 30, 2023 2022 2021 Domestic $ 397.2 $ 799.9 $ 105.9 Foreign 15.7 95.4 108.1 Earnings before Income Taxes and Equity Method Loss $ 412.9 $ 895.3 $ 214.0 Income tax expense $ 99.7 $ 85.7 $ 58.2 Effective income tax rate 24.1 % 9.6 % 27.2 %

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Year Ended September 30, 2023 2022 2021 Net Earnings from Continuing Operations Net earnings from continuing operations $ 301.3 $ 735.0 $ 104.9 Impact of redeemable NCI 11.0 — (11.0) Net earnings from continuing operations for basic earnings per share $ 312.3 $ 735.0 $ 93.9 Impact of interest expense, net of tax, related to convertible senior notes 10.9 1.5 — Net earnings from continuing operations for diluted earnings per share $ 323.2 $ 736.5 $ 93.9 Net Earnings from Discontinued Operations Net earnings from discontinued operations for basic earnings per share $ — $ 21.6 $ 61.8 Dilutive impact of Old BellRing net earnings from discontinued operations — — (0.1) Net earnings from discontinued operations for diluted earnings per share $ — $ 21.6 $ 61.7 Net Earnings Net earnings for basic earnings per share $ 312.3 $ 756.6 $ 155.7 Net earnings for diluted earnings per share $ 323.2 $ 758.1 $ 155.6 shares in millions Weighted-average shares for basic earnings per share 60.0 60.9 64.2 Effect of dilutive securities: Stock options 0.4 0.3 0.6 Stock appreciation rights — 0.1 0.1 Restricted stock units 0.5 0.5 0.3 Market-based performance restricted stock units 0.6 0.1 0.1 Earnings-based performance restricted stock units 0.1 0.1 — Shares issuable upon conversion of convertible senior notes 5.4 0.7 — Total dilutive securities 7.0 1.8 1.1 Weighted-average shares for diluted earnings per share 67.0 62.7 65.3 Earnings from Continuing Operations per Common Share: Basic $ 5.21 $ 12.07 $ 1.46 Diluted $ 4.82 $ 11.75 $ 1.44 Earnings from Discontinued Operations per Common Share: Basic $ — $ 0.35 $ 0.96 Diluted $ — $ 0.34 $ 0.94 Earnings per Common Share: Basic $ 5.21 $ 12.42 $ 2.42 Diluted $ 4.82 $ 12.09 $ 2.38
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	Year Ended September 30, 2023 2022 2021 Restricted stock units 0.1 0.3 — Market-based performance restricted stock units 0.1 0.1 —

Supplemental Operations State_2

Supplemental Operations Statement and Cash Flow Information (Tables)	12 Months Ended
	Sep. 30, 2023
Supplemental Operations Statement and Cash Flow Information [Abstract]
Supplemental Operations Statement and Cash Flow Information	Year Ended September 30, 2023 2022 2021 Advertising expenses $ 124.1 $ 93.2 $ 112.3 Research and development expenses 22.9 18.9 21.9 Interest income (20.9) (4.4) (0.6) Interest paid 300.2 320.0 348.2 Income taxes paid 114.7 45.8 45.6 Accrued additions to property 37.9 36.4 38.3

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Sep. 30, 2023
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	September 30, 2023 2022 Receivables, net Trade $ 451.0 $ 499.4 Pet Food net receivable (see Note 6) 35.5 — Income tax receivable 8.3 17.4 Related party 6.9 4.4 Other 13.2 25.3 514.9 546.5 Allowance for credit losses (2.5) (2.3) $ 512.4 $ 544.2 Inventories Raw materials and supplies $ 155.9 $ 130.9 Work in process 24.4 21.1 Finished products 573.6 361.9 Flocks 36.0 35.2 $ 789.9 $ 549.1 Other Assets Pension asset $ 110.3 $ 93.9 Operating ROU assets 176.2 122.9 Other investments 6.1 26.9 Derivative assets 11.3 3.0 Software implementation costs 18.0 — Other 38.1 24.2 $ 360.0 $ 270.9 Accounts Payable Trade $ 339.7 $ 362.1 Book cash overdrafts 1.3 53.3 Related party 13.8 26.1 Other 14.0 11.2 $ 368.8 $ 452.7 Other Current Liabilities Advertising and promotion $ 74.0 $ 47.2 Accrued interest 67.0 69.5 Accrued compensation 128.2 63.4 Derivative liabilities 16.1 25.9 Operating lease liabilities 22.8 25.5 Accrued freight 16.4 25.1 Other accrued taxes 21.4 19.1 Other 89.5 94.3 $ 435.4 $ 370.0 Other Liabilities Pension and other postretirement benefit obligations $ 42.8 $ 45.6 Derivative liabilities — 49.1 Deferred compensation 36.2 33.1 Operating lease liabilities 169.6 113.7 Other 28.1 25.4 $ 276.7 $ 266.9

Derivative Financial Instrume_2

Derivative Financial Instruments and Hedging (Tables)	12 Months Ended
	Sep. 30, 2023
Derivative [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions	September 30, 2023 2022 Commodity contracts $ 215.0 $ 145.0 Energy contracts 48.9 23.7 FX contracts 3.0 3.2 Interest rate swap 700.0 200.0 Interest rate swaps - Rate-lock swaps — 849.3 Interest rate swaps - Option — 332.6 PHPC Warrants — 16.9
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	September 30, Balance Sheet Location 2023 2022 Asset Derivatives: Commodity contracts Prepaid expenses and other current assets $ 1.2 $ 12.9 Energy contracts Prepaid expenses and other current assets 2.5 13.6 Interest rate swaps Prepaid expenses and other current assets 10.6 3.4 Commodity contracts Other assets — 0.5 Interest rate swaps Other assets 11.3 2.5 $ 25.6 $ 32.9 Liability Derivatives: Commodity contracts Other current liabilities $ 14.1 $ 1.5 Energy contracts Other current liabilities 2.0 1.8 FX contracts Other current liabilities — 0.1 Interest rate swaps Other current liabilities — 22.5 Interest rate swaps Other liabilities — 48.1 PHPC Warrants Other liabilities — 1.0 $ 16.1 $ 75.0
Schedule of Derivative Instruments, Loss (Gain) in Statement of Financial Performance	Derivative Instruments Statement of Operations Location Year Ended September 30, 2023 2022 2021 Commodity contracts Cost of goods sold $ 28.5 $ (32.2) $ (11.3) Energy contracts Cost of goods sold 6.7 (28.5) (43.1) FX contracts Selling, general and administrative expenses (0.1) 0.1 0.1 Interest rate swaps Income on swaps, net (39.9) (268.0) (122.8) PHPC Warrants Other income, net (1.0) (8.2) (7.7)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	September 30, 2023 September 30, 2022 Total Level 1 Level 2 Total Level 1 Level 2 Assets: Deferred compensation investments $ 13.0 $ 13.0 $ — $ 12.0 $ 12.0 $ — Derivative assets 25.6 — 25.6 32.9 — 32.9 Equity securities 0.2 0.2 — 32.1 32.1 — Investment in BellRing — — — 94.8 94.8 — $ 38.8 $ 13.2 $ 25.6 $ 171.8 $ 138.9 $ 32.9 Liabilities: Deferred compensation liabilities $ 36.8 $ — $ 36.8 $ 33.7 $ — $ 33.7 Derivative liabilities 16.1 — 16.1 75.0 1.0 74.0 $ 52.9 $ — $ 52.9 $ 108.7 $ 1.0 $ 107.7
Fair Value Measurements, Nonrecurring	Balance, September 30, 2021 $ — Net gain related to assets held for sale 9.4 Proceeds from the sale of assets held for sale (10.3) Transfers of assets into held for sale 1.0 Balance, September 30, 2022 $ 0.1 Proceeds from the sale of assets held for sale (0.1) Balance, September 30, 2023 $ —

Leases (Tables)

Leases (Tables)	12 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Summary of ROU Assets and Lease Liabilities	September 30, 2023 2022 ROU assets: Other assets $ 176.2 $ 122.9 Lease liabilities: Other current liabilities $ 22.8 $ 25.5 Other liabilities 169.6 113.7 Total lease liabilities $ 192.4 $ 139.2
Maturities of Lease Liabilities, under ASC Topic 842	Fiscal 2024 $ 33.5 Fiscal 2025 37.1 Fiscal 2026 36.9 Fiscal 2027 32.8 Fiscal 2028 27.1 Thereafter 75.2 Total future minimum payments $ 242.6 Less: Implied interest 50.2 Total lease liabilities $ 192.4
Lease, Cost	Year Ended September 30, 2023 2022 2021 Total operating lease expense $45.8 $45.5 $40.1 Variable lease expense 5.3 5.2 4.8 Short-term lease expense 7.7 9.4 7.5 Weighted-average remaining lease term 8 years 9 years 9 years Weighted-average IBR 5.99% 5.26% 4.70%

Long Term Debt (Tables)

Long Term Debt (Tables)	12 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	September 30, 2023 2022 2.50% convertible senior notes maturing August 2027 $ 575.0 $ 575.0 4.50% senior notes maturing September 2031 1,049.7 1,270.5 4.625% senior notes maturing April 2030 1,385.4 1,482.2 5.50% senior notes maturing December 2029 1,235.0 1,235.0 5.625% senior notes maturing January 2028 939.9 940.9 5.75% senior notes maturing March 2027 459.3 459.3 Fourth Incremental Term Loan 400.0 — Municipal bond 5.3 6.4 $ 6,049.6 $ 5,969.3 Less: Current portion of long-term debt 1.1 1.1 Debt issuance costs, net 42.0 50.1 Plus: Unamortized premium, net 32.5 38.5 Total long-term debt $ 6,039.0 $ 5,956.6
Repayments of Long-Term Debt	The following table presents the Company’s (i) principal repayments of debt, which, net of discounts, were included in the Consolidated Statements of Cash Flows, (ii) principal amounts of debt exchanged (refer to “Debt Transactions in Connection with BellRing” above), which were not included in the Consolidated Statements of Cash Flows and (iii) the associated (gain) loss related to such repayments and exchanges included in “(Gain) loss on extinguishment of debt, net” in the Consolidated Statements of Operations. (Gain) Loss on Extinguishment of Debt, net Debt Instrument Principal Amount Repaid Principal Amount Exchanged Debt Discounts (Received) / Premiums Paid Write-off of Debt Issuance Costs / Write-off of Unamortized Premiums Year Ended September 30, 2023 4.50% senior notes $ 220.8 $ — $ (31.5) $ 1.7 $ — 4.625% senior notes 96.8 — (11.4) 0.5 (0.9) 5.625% senior notes 1.0 — — — — Third Incremental Term Loan 30.1 99.9 — 1.1 — Municipal bond 1.1 — — — — Total $ 349.8 $ 99.9 $ (42.9) $ 3.3 $ (0.9) Year Ended September 30, 2022 4.50% senior notes $ 529.5 $ — $ (74.7) $ 6.0 $ — 4.625% senior notes 167.8 — (21.9) 1.1 (1.8) 5.50% senior notes 15.0 — (1.2) 0.1 (0.2) 5.75% senior notes 840.0 — 24.1 5.0 (13.3) First Incremental Term Loan — 840.0 — 3.5 — Second Incremental Term Loan 107.7 342.3 — 0.7 — Municipal bond 1.1 — — — — Total $ 1,661.1 $ 1,182.3 $ (73.7) $ 16.4 $ (15.3) Year Ended September 30, 2021 5.00% senior notes $ 1,697.3 $ — $ 74.3 $ 18.9 $ — Municipal bond 1.0 — — — — Total $ 1,698.3 $ — $ 74.3 $ 18.9 $ —
Schedule of Maturities of Long-term Debt	As of September 30, 2023, expected principal payments on the Company’s debt for the next five fiscal years were: Fiscal 2024 $ 1.1 Fiscal 2025 1.2 Fiscal 2026 401.2 Fiscal 2027 (a) 1,035.6 Fiscal 2028 940.4 (a) Includes principal payments of $575.0 related to the Company’s 2.50% convertible senior notes.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Sep. 30, 2023
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, 2023 and a statement of the funded status and amounts recognized on the Consolidated Balance Sheets as of September 30, 2023 and 2022. North America Other International As of and for the Year Ended September 30, As of and for the Year Ended September 30, 2023 2022 2023 2022 Change in benefit obligation Benefit obligation at beginning of year $ 95.5 $ 133.3 $ 421.1 $ 821.3 Service cost 2.2 4.3 — — Interest cost 5.3 3.5 23.3 15.7 Plan participants’ contributions 0.3 0.4 — — Net actuarial gain (5.4) (38.9) (37.5) (251.6) Benefits paid (5.4) (5.9) (25.9) (28.4) Currency translation 0.1 (1.2) 41.0 (135.9) Benefit obligation at end of year $ 92.6 $ 95.5 $ 422.0 $ 421.1 Change in fair value of plan assets Fair value of plan assets at beginning of year $ 102.9 $ 136.6 $ 507.3 $ 970.9 Actual return on plan assets 10.1 (27.1) (14.3) (273.0) Employer contributions 0.1 0.4 — — Plan participants’ contributions 0.3 0.4 — — Benefits paid (5.4) (5.9) (25.9) (28.4) Currency translation 0.2 (1.5) 49.4 (162.1) Other — — (0.1) (0.1) Fair value of plan assets at end of year 108.2 102.9 516.4 507.3 Funded status $ 15.6 $ 7.4 $ 94.4 $ 86.2 Amounts recognized in assets or liabilities Other assets $ 15.9 $ 7.7 $ 94.4 $ 86.2 Other liabilities (0.3) (0.3) — — Net amount recognized $ 15.6 $ 7.4 $ 94.4 $ 86.2 Amounts recognized in accumulated OCI Net actuarial (gain) loss $ (2.7) $ 5.0 $ 47.7 $ 40.2 Prior service cost 0.4 0.6 10.3 10.7 Total $ (2.3) $ 5.6 $ 58.0 $ 50.9 Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 6.06 % 5.65 % n/a n/a Discount rate — Canadian plans 5.68 % 5.12 % n/a n/a Discount rate — Other international plans n/a n/a 5.67 % 5.15 % 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 3.02 % 3.85 % The following table provides a reconciliation of the changes in the North America other postretirement benefit obligations over the two year period ended September 30, 2023 and a statement of the funded status and amounts recognized on the Consolidated Balance Sheets as of September 30, 2023 and 2022. Besides the North America plans, the Company does not maintain any other postretirement benefit plans. As of and for the Year Ended September 30, 2023 2022 Change in benefit obligation Benefit obligation at beginning of year $ 48.3 $ 66.5 Service cost 0.3 0.5 Interest cost 2.5 1.5 Net actuarial gain (3.0) (17.4) Benefits paid (2.3) (2.3) Currency translation — (0.5) Benefit obligation at end of year $ 45.8 $ 48.3 Change in fair value of plan assets Employer contributions 2.3 2.3 Benefits paid (2.3) (2.3) Fair value of plan assets at end of year — — Funded status $ (45.8) $ (48.3) Amounts recognized in assets or liabilities Other current liabilities (3.3) (3.0) Other liabilities (42.5) (45.3) Net amount recognized $ (45.8) $ (48.3) Amounts recognized in accumulated OCI Net actuarial loss $ (11.7) $ (9.2) Prior service credit (0.7) (5.4) Total $ (12.4) $ (14.6) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 6.01 % 5.62 % Discount rate — Canadian plans 5.67 % 5.12 % 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, 2023 September 30, 2022 Total Level 1 Level 2 Total Level 1 Level 2 Equities $ 11.9 $ — $ 11.9 $ 11.0 $ — $ 11.0 Fixed income and bonds 5.2 — 5.2 5.0 — 5.0 Cash and cash equivalents 4.1 4.1 — 8.9 8.9 — Fair value of plan assets in the fair value hierarchy 21.2 4.1 17.1 24.9 8.9 16.0 Equities 58.1 — — 45.1 — — Fixed income and bonds 27.6 — — 29.9 — — Real assets 1.3 — — 3.0 — — Investments measured at NAV (a) 87.0 — — 78.0 — — Total plan assets $ 108.2 $ 4.1 $ 17.1 $ 102.9 $ 8.9 $ 16.0 Other International September 30, 2023 September 30, 2022 Total Level 1 Level 2 Total Level 1 Level 2 Fixed income and bonds $ 280.4 $ 280.4 $ — $ 321.3 $ 321.3 $ — Liability driven instruments 91.6 91.6 — 77.9 77.9 — Cash and cash equivalents 17.4 17.4 — 10.6 10.6 — Fair value of plan assets in the fair value hierarchy 389.4 389.4 — 409.8 409.8 — Fixed income and bonds 107.8 — — 78.5 — — Liability driven instruments 19.2 — — 16.9 — — Real assets — — — 2.1 — — Investments measured at NAV (a) 127.0 — — 97.5 — — Total plan assets $ 516.4 $ 389.4 $ — $ 507.3 $ 409.8 $ — (a) In accordance with ASC Topic 820, certain investments were measured at NAV. In cases where the fair value was measured at NAV using the practical expedient provided for in ASC Topic 820, 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	Pension Benefits Other Benefits Subsidy Receipts Fiscal 2024 $ 26.7 $ 3.5 $ 0.1 Fiscal 2025 27.6 3.5 0.1 Fiscal 2026 28.9 3.5 0.1 Fiscal 2027 30.1 3.5 0.2 Fiscal 2028 30.7 3.5 0.2 Fiscal 2029 - 2033 172.2 17.8 1.1
Pension Benefits
Defined Benefit Plan Disclosure
Schedule of net benefit costs and assumptions used in calculation	The following tables present the components of net periodic benefit (income) cost for the pension plans including amounts recognized in OCI. Service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit (income) cost were reported in “Other income, net” in the Consolidated Statements of Operations. North America Year Ended September 30, 2023 2022 2021 Components of net periodic benefit (income) cost Service cost $ 2.2 $ 4.3 $ 3.9 Interest cost 5.3 3.5 3.2 Expected return on plan assets (7.5) (7.0) (6.4) Recognized net actuarial (gain) loss (0.2) 1.6 2.4 Recognized prior service cost 0.1 0.1 0.1 Net periodic benefit (income) cost $ (0.1) $ 2.5 $ 3.2 Weighted-average assumptions used to determine net benefit (income) cost Discount rate — U.S. plans 5.65 % 3.05 % 3.01 % Discount rate — Canadian plans 5.12 % 3.32 % 2.71 % Rate of compensation increase — U.S. plans 3.00 % 3.00 % 3.00 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Expected return on plan assets — U.S. plans 6.50 % 5.75 % 5.40 % Expected return on plan assets — Canadian plans 5.75 % 5.25 % 5.25 % Changes in plan assets and benefit obligation recognized in OCI Net gain $ (8.0) $ (4.7) $ (14.5) Recognized gain (loss) 0.2 (1.6) (2.4) Prior service cost (a) — — 0.5 Recognized prior service cost (0.1) (0.1) (0.1) Total recognized in OCI (before tax effects) $ (7.9) $ (6.4) $ (16.5) (a) Amounts reported for the year ended September 30, 2021 represent the impact of fiscal 2020 union negotiations that were ratified subsequent to September 30, 2020. Other International Year Ended September 30, 2023 2022 2021 Components of net periodic benefit income Interest cost $ 23.3 $ 15.7 $ 15.2 Expected return on plan assets (30.8) (24.8) (24.9) Recognized net actuarial loss 0.1 — — Recognized prior service cost 0.4 0.4 0.5 Net periodic benefit income $ (7.0) $ (8.7) $ (9.2) Weighted-average assumptions used to determine net benefit income Discount rate 5.15 % 2.05 % 1.73 % Rate of compensation increase 3.85 % 3.45 % 2.65 % Expected return on plan assets 5.63 % 2.73 % 2.38 % Changes in plan assets and benefit obligation recognized in OCI Net loss $ 7.6 $ 46.2 $ 26.4 Recognized loss (0.1) — — Recognized prior service cost (0.4) (0.4) (0.5) Total recognized in OCI (before tax effects) $ 7.1 $ 45.8 $ 25.9
Other Benefits
Defined Benefit Plan Disclosure
Schedule of net benefit costs and assumptions used in calculation	The following table presents the components of net periodic benefit income for the other postretirement benefit plans including amounts recognized in OCI. Service cost was reported in “Cost of goods sold” and “Selling, general and administrative expenses” and all other components of net periodic benefit income were reported in “Other income, net” in the Consolidated Statements of Operations. Year Ended September 30, 2023 2022 2021 Components of net periodic benefit income Service cost $ 0.3 $ 0.5 $ 0.5 Interest cost 2.5 1.5 1.5 Recognized net actuarial (gain) loss (0.5) 0.6 1.1 Recognized prior service credit (4.7) (4.6) (4.7) Net periodic benefit income $ (2.4) $ (2.0) $ (1.6) Weighted-average assumptions used to determine net benefit income Discount rate — U.S. plans 5.62 % 2.89 % 2.79 % Discount rate — Canadian plans 5.12 % 3.45 % 2.78 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Changes in benefit obligation recognized in OCI Net gain $ (3.0) $ (17.5) $ (4.3) Recognized net actuarial gain (loss) 0.5 (0.6) (1.1) Recognized prior service credit 4.7 4.6 4.7 Total recognized in OCI (before tax effects) $ 2.2 $ (13.5) $ (0.7)

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Sep. 30, 2023
Post Stock Settled
Share-based Payment Award [Line Items]
Stock Appreciation Rights, Activity	$ in millions, except price per share SARs Weighted- Average Exercise Price Per Share Weighted- Aggregate Outstanding at September 30, 2022 81,554 $ 33.42 Granted — Exercised (29,656) 28.28 Forfeited — Expired — Outstanding at September 30, 2023 51,898 36.35 1.23 $ 2.6 Vested and expected to vest as of September 30, 2023 51,898 36.35 1.23 2.6 Exercisable at September 30, 2023 51,898 36.35 1.23 2.6 Upon exercise of each SAR, 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 SARs exercised was $1.9, $3.0 and $3.2 during the years ended September 30, 2023, 2022 and 2021, respectively. There were no SARs granted during the years ended September 30, 2023, 2022 or 2021.
Restricted Stock Units, Activity	RSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 1,348,806 $ 68.38 Granted 526,035 90.85 Vested (763,124) 67.34 Forfeited (51,485) 74.06 Nonvested at September 30, 2023 1,060,232 79.99
Post Stock Options
Share-based Payment Award [Line Items]
Stock Options, Activity	$ in millions, except price per share Stock Options Weighted- Average Exercise Price Per Share Weighted- Aggregate Outstanding at September 30, 2022 1,011,315 $ 48.75 Granted — — Exercised (262,607) 39.57 Forfeited — — Expired — — Outstanding at September 30, 2023 748,708 51.96 3.63 $ 25.3 Vested and expected to vest as of September 30, 2023 748,708 51.96 3.63 25.3 Exercisable at September 30, 2023 748,708 51.96 3.63 25.3
Post Cash Settled
Share-based Payment Award [Line Items]
Restricted Stock Units, Activity	Cash RSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 29,063 $ 34.68 Granted — — Vested (16,015) 34.68 Forfeited — — Nonvested at September 30, 2023 13,048 34.68
Earnings-Based Restricted Stock Units
Share-based Payment Award [Line Items]
Performance-Based Restricted Stock Units	Earnings PRSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 272,427 $ 70.46 Granted 142,939 94.09 Vested (148,531) 70.36 Forfeited (7,293) 83.83 Nonvested at September 30, 2023 259,542 83.20
Market-based performance shares
Share-based Payment Award [Line Items]
Performance-Based Restricted Stock Units	Market PRSUs Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2022 374,402 $ 106.10 Granted 142,843 156.05 Vested — — Forfeited (23,140) 102.95 Nonvested at September 30, 2023 494,105 120.69
Performance RSU, Valuation Assumptions	2023 2022 2021 Expected term (in years) 3.0 3.0 3.0 Expected stock price volatility 29.1% 27.7% 28.3% Risk-free interest rate 4.1% 0.9% 0.2% Expected dividends 0% 0% 0% Fair value (per Market PRSU) $156.05 $163.63 $152.58

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Sep. 30, 2023
Equity, Attributable to Parent [Abstract]
Repurchases of Common Stock	Year Ended September 30, 2023 2022 2021 Shares repurchased (in millions) 4.4 4.9 4.0 Average price per share (a) $ 87.13 $ 90.02 $ 98.37 Total share repurchase costs (b) $ 387.1 $ 439.0 $ 393.7 (a) Average price per share excludes broker’s commissions, which are included in “Total share repurchase costs” within this table. Average price per share during the year ended September 30, 2022 was $103.79 prior to the BellRing Spin-off and $81.53 subsequent to the BellRing Spin-off. (b) “Purchases of treasury stock” in the Consolidated Statements of Cash Flows for the year ended September 30, 2022 included $4.0 of repurchases of common stock that were accrued in fiscal 2021 but did not settle until fiscal 2022. “Purchases of treasury stock” in the Consolidated Statements of Cash Flows for the year ended September 30, 2021 included $7.4 of repurchases of common stock that were accrued in fiscal 2020 but did not settle until fiscal 2021.

Segments (Tables)

Segments (Tables)	12 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Year Ended September 30, 2023 2022 2021 Net Sales Post Consumer Brands $ 3,033.1 $ 2,242.7 $ 1,915.3 Weetabix 512.1 477.3 477.5 Foodservice 2,425.9 2,095.0 1,615.6 Refrigerated Retail 1,019.7 1,036.6 974.5 Eliminations and Corporate 0.2 (0.4) (2.2) Total $ 6,991.0 $ 5,851.2 $ 4,980.7 Segment Profit Post Consumer Brands $ 378.8 $ 314.6 $ 316.6 Weetabix 73.9 109.5 115.4 Foodservice 349.5 151.0 61.7 Refrigerated Retail 69.2 57.1 75.9 Total segment profit 871.4 632.2 569.6 General corporate expenses and other 222.7 196.8 52.6 Impairment of goodwill 42.2 — — Interest expense, net 279.1 317.8 332.6 (Gain) loss on extinguishment of debt, net (40.5) (72.6) 93.2 Income on swaps, net (39.9) (268.0) (122.8) Gain on investment in BellRing (5.1) (437.1) — Earnings before income taxes and equity method loss $ 412.9 $ 895.3 $ 214.0 Net sales by product Cereal $ 2,730.8 $ 2,595.0 $ 2,333.3 Eggs and egg products 2,304.0 2,026.1 1,556.1 Side dishes (including potato products) 732.0 652.4 575.0 Pet food 679.8 — — Cheese and dairy 191.5 214.3 223.0 Sausage 163.6 171.2 165.9 Nut butters 100.5 111.7 58.7 Protein-based products 34.1 12.9 — Other 55.4 68.5 70.9 Eliminations (0.7) (0.9) (2.2) Total $ 6,991.0 $ 5,851.2 $ 4,980.7 Additions to property and intangibles Post Consumer Brands $ 112.8 $ 91.2 $ 81.2 Weetabix 30.1 26.7 19.6 Foodservice and Refrigerated Retail 144.0 136.1 89.7 Corporate (a) 24.2 20.8 0.4 Total $ 311.1 $ 274.8 $ 190.9 Depreciation and amortization Post Consumer Brands $ 157.3 $ 133.1 $ 122.0 Weetabix 35.9 37.5 39.0 Foodservice 128.7 127.5 126.0 Refrigerated Retail 76.1 78.4 75.5 Total segment depreciation and amortization 398.0 376.5 362.5 Corporate 9.1 3.7 4.0 Total $ 407.1 $ 380.2 $ 366.5 September 30, 2023 2022 Assets Post Consumer Brands $ 4,782.2 $ 3,529.1 Weetabix 1,737.8 1,591.3 Foodservice and Refrigerated Retail 4,921.6 5,022.7 Corporate 205.1 1,164.9 Total assets $ 11,646.7 $ 11,308.0 (a) During the years ended September 30, 2023 and 2022, the Company had non-cash exchanges of fixed assets of $8.1 and $19.5, respectively, which were included in the Corporate additions to property and intangibles.

Background (Details)

Background (Details)	Mar. 10, 2022
Post | New BellRing Common Stock
Distribution of ownership in subsidiary, percentage	80.10%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Weetabix Segment | Operating Segments
Business Acquisition
Accounts Receivable, Sale	$ 92.5	$ 111.7

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Property, Plant and Equipment, Net [Abstract]
Depreciation	$ 245.3	$ 232.9	$ 222.2
Property, plant and equipment, gross	3,769.4	3,269.3
Accumulated depreciation	(1,748)	(1,517.4)
Property, net	2,021.4	1,751.9
Land
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	109.9	92.2
Building and leasehold improvements
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 1,042.9	932.7
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	35 years
Machinery and equipment
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 2,312.2	1,951.1
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	30 years
Software
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 113.3	110.6
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	$ 191.1	$ 182.7

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Finite-Lived and Indefinite-Lived, Intangible Assets
Amortization of intangible assets	$ 160.7	$ 146	$ 143.2
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2024	179.9
2025	178.7
2026	178.7
2027	178.7
2028	173.5
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	3,421.3	2,777.4
Finite-Lived Intangible Assets, Accumulated Amortization	(1,242)	(1,076.8)
Finite-Lived Intangible Assets, Net	2,179.3	1,700.6
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Carrying amount, total	4,454.4	3,789
Other intangible assets, net	3,212.4	2,712.2
Customer Relationships
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	2,535.5	2,129.7
Finite-Lived Intangible Assets, Accumulated Amortization	(940.7)	(816.4)
Finite-Lived Intangible Assets, Net	1,594.8	1,313.3
Trademarks
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	885.8	647.7
Finite-Lived Intangible Assets, Accumulated Amortization	(301.3)	(260.4)
Finite-Lived Intangible Assets, Net	584.5	387.3
Trademarks
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Indefinite-lived Intangible Assets (Excluding Goodwill)	$ 1,033.1	$ 1,011.6
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	11%	23%	22%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Capitalized Software Implementation Costs (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Accounting Policies [Abstract]
Capitalized Software Implementation Costs	$ 20.4	$ 7.6

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Cost of Products Sold (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Cost Of Goods Sold, Storage And Warehouse Costs	$ 263.2	$ 204	$ 167.7

Summary of Significant Accoun_9

Summary of Significant Accounting Policies Advertising (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Accounting Policies [Abstract]
Prepaid Advertising	$ 1.3	$ 1.4

Discontinued Operations and D_3

Discontinued Operations and Disposal Groups (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Mar. 10, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payment of merger consideration			$ 550.4
Disposal Group, Including Discontinued Operation, Revenue			541.9	$ 1,246
Disposal Group, Including Discontinued Operation, Costs of Goods Sold			390.3	859.8
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)			151.6	386.2
Disposal Group, Including Discontinued Operation, General and Administrative Expense			68.5	167.1
Disposal Group, Including Discontinued Operation, Amortization of intangible assets			8.7	51.2
Disposal Group, Including Discontinued Operation, Other operating income, net			0	(0.1)
Disposal Group, Including Discontinued Operation, Operating Income (Loss)			74.4	168
Disposal Group, Including Discontinued Operation, Interest Expense			13.1	43.2
Disposal Group, Including Discontinued Operation, Loss on extinguishment and refinancing of debt, net			17.6	1.6
Earnings from Discontinued Operations before Income Taxes			43.7	123.2
Disposal Group, Including Discontinued Operation, Income tax expense			10.3	28.4
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest			33.4	94.8
Net earnings attributable to noncontrolling interest from discontinued operations		$ 0	11.8	33
Net earnings from discontinued operations, net of tax and noncontrolling interest		$ 0	21.6	61.8
Other assets of discontinued operations	$ 633
Other liabilities of discontinued operations	1,064.6
Disposal Group, Including Discontinued Operation, Net Assets	(431.6)
Additional Paid-in Capital
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
BellRing Spin-Off	442.5		442.5
Foreign Currency Translation Adjustments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
BellRing Spin-Off	$ 2.3		2.3
BellRing Brands, Inc. | BellRing Common Stock
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Par value of common stock		$ 0.01
Post
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Separation Costs		$ 0.1	29.9	$ 1.6
BellRing | 7.00% Senior Notes due 2030 | Senior Notes
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-Term Debt, Gross			$ 840
Post shareholders | BellRing Common Stock
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Conversion of Stock, Shares Received	1.267788
Post | BellRing
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	14.20%		3.40%
Post | New BellRing Common Stock
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Distribution of ownership in subsidiary, shares	78,100,000
Distribution of ownership in subsidiary, percentage	80.10%

PHPC (Details)

PHPC (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	May 30, 2023	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Proceeds from subsidiary initial public offering	$ 0	$ 0	$ 305
Investments held in trust	0	346.8		$ 353.4
Redeemable noncontrolling interest	0	306.6		312.5
Initial public offering costs			17.9
Deferred Offering Costs		10.7
Schedule of Equity Method Investments [Line Items]
Gain on write-off of underwriting commissions	10.7
Investments held in trust	0	346.8		353.4
Return of subsidiary investments held in trust account	345	0	0
Redeemable noncontrolling interest	0	306.6		$ 312.5
Maximum interest to pay dissolution expenses		$ 0.1
Net earnings attributable to redeemable NCI, subsequent to IPO			5.8
Initial public offering costs			(17.9)
Series A common stock included in each unit		1
Proceeds from subsidiary initial public offering	0	$ 0	305
Deferred Offering Costs		$ 10.7
Warrants included in each PHPC unit		0.333
Selling, general and administrative expenses
Equity Method Investments and Joint Ventures [Abstract]
Initial public offering costs			(1)
Schedule of Equity Method Investments [Line Items]
Initial public offering costs			1
Redeemable Noncontrolling Interest
Equity Method Investments and Joint Ventures [Abstract]
Initial public offering costs			(16.9)
Schedule of Equity Method Investments [Line Items]
Initial public offering costs			16.9
PHPC
Equity Method Investments and Joint Ventures [Abstract]
Proceeds from subsidiary initial public offering		$ 345
Schedule of Equity Method Investments [Line Items]
Proceeds from subsidiary initial public offering		$ 345
PHPC Sponsor | Series F Common Stock
Schedule of Equity Method Investments [Line Items]
Common Stock, Shares, Outstanding		8,600,000
PHPC | Post
Equity Method Investments and Joint Ventures [Abstract]
Noncontrolling Interest, Ownership Percentage by Parent		31%		31%
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		31%		31%
PHPC | Public Shareholders
Equity Method Investments and Joint Ventures [Abstract]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		69%		69%
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		69%		69%
PHPC Units
Equity Method Investments and Joint Ventures [Abstract]
Share Price		$ 10
Schedule of Equity Method Investments [Line Items]
Redemption Price				$ 10.24
Common Unit, Issued		34,500,000
Share Price		$ 10
PHPC Units | PHPC
Equity Method Investments and Joint Ventures [Abstract]
Proceeds from subsidiary initial public offering			345
Schedule of Equity Method Investments [Line Items]
Proceeds from subsidiary initial public offering			345
PHPC Units | PHPC Sponsor
Schedule of Equity Method Investments [Line Items]
Return of subsidiary investments held in trust account	40.9
Common Unit, Issued		4,000,000		4,000,000
PHPC warrants
Schedule of Equity Method Investments [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 11.50
PHPC Private Placement Units
Equity Method Investments and Joint Ventures [Abstract]
Share Price		10
Schedule of Equity Method Investments [Line Items]
Share Price		10
Proceeds from Issuance of Private Placement			$ 10.9
PHPC Private Placement Units | PHPC Sponsor
Schedule of Equity Method Investments [Line Items]
Common Unit, Issued			1,100,000
PHPC Forward Purchase Units
Equity Method Investments and Joint Ventures [Abstract]
Share Price		10
Schedule of Equity Method Investments [Line Items]
Share Price		$ 10
PHPC Forward Purchase Units | Maximum
Equity Method Investments and Joint Ventures [Abstract]
Common Unit, Authorized			10,000,000
Schedule of Equity Method Investments [Line Items]
Common Unit, Authorized			10,000,000
PHPC Forward Purchase Units | PHPC Sponsor | Maximum
Equity Method Investments and Joint Ventures [Abstract]
Potential Proceeds from Issuance of Forward Purchase Agreement		$ 100
Schedule of Equity Method Investments [Line Items]
Potential Proceeds from Issuance of Forward Purchase Agreement		100
Redeemable Noncontrolling Interest
Equity Method Investments and Joint Ventures [Abstract]
Redeemable noncontrolling interest	0	306.6	$ 305		$ 0
Initial public offering costs	0	0	16.9
Schedule of Equity Method Investments [Line Items]
Redemption of PHPC Series A Common Stock	(312.5)	0	0
Redeemable noncontrolling interest	0	306.6	305		$ 0
Initial public offering	0	0	271.2
Net earnings attributable to redeemable NCI, subsequent to IPO	12.1	6.7	5.8
Noncontrolling interest, Redemption value adjustment	(5.9)	(1.6)	0
Noncontrolling Interest, Change in Redemption Value	(6.2)	(5.1)	28
Initial public offering costs	0	0	(16.9)
Warrant Initial Valuation	$ 0	$ 0	$ 16.9

8th Ave (Details)

8th Ave (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Oct. 01, 2018
Schedule of Equity Method Investments [Line Items]
Equity method (loss) earnings, net of tax	$ (0.3)	$ (67.1)	$ (43.9)
Net Sales	6,991	5,851.2	4,980.7
Accounts payable	368.8	452.7
Other liabilities	276.7	266.9
Gross Profit	1,881.7	1,467.5	1,428.1
Net earnings from continuing operations, including noncontrolling interests	312.9	775.9	206.7
Net Earnings	301.3	756.6	166.7
8th Avenue
Schedule of Equity Method Investments [Line Items]
Net Sales		1,089	900.8
Gross Profit		159.9	132.3
Net earnings from continuing operations, including noncontrolling interests		(251.3)	(60.6)
8th Avenue
Schedule of Equity Method Investments [Line Items]
Net Sales	8	8.1	6.7
Accounts Receivable | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Receivables, net	3.9	4.4
Accounts Payable | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Accounts payable	13.3	26.1
Other Assets | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, after Allowance for Credit Loss, Noncurrent	12.9	0
Other Liabilities | 8th Avenue
Schedule of Equity Method Investments [Line Items]
Other liabilities	0.7	0.7
Selling, general and administrative expenses | 8th Avenue
Schedule of Equity Method Investments [Line Items]
MSA and Advisory Income	$ (3.1)	(3.2)	$ (3.5)
8th Avenue
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	60.50%		60.50%
Equity method loss available to Common Shareholders			$ (36.7)
Amortization of basis difference, net of tax			6.8
Equity method (loss) earnings, net of tax			(43.5)
Total Basis Difference Recognized				$ 70.3
Purchases from and Royalties paid to Related Party	$ 83.9	102.9	54.1
Preferred Stock Dividends and Other Adjustments		40.4	36.3
Net Earnings		(210.9)	(24.3)
8th Avenue | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 0	$ 0	$ 66.6

BRBR (Details)

BRBR (Details) - USD ($) shares in Millions, $ in Millions			12 Months Ended
	Nov. 25, 2022	Aug. 08, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Mar. 10, 2022
Schedule of Equity Method Investments [Line Items]
Investment in BellRing			$ 0	$ 94.8
Gain on investment in BellRing			$ (5.1)	$ (437.1)	$ 0
Post | BellRing
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Common Stock, Amount				4.6		19.4
Noncontrolling Interest, Ownership Percentage by Parent				3.40%		14.20%
Noncontrolling Interest, Common Stock, Transfer	4.6	14.8

WBX East Africa and Alpen (Deta

WBX East Africa and Alpen (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Schedule of Equity Method Investments [Line Items]
Other current liabilities	$ 435.4	$ 370
Equity method (loss) earnings, net of tax	(0.3)	(67.1)	$ (43.9)
Other	$ 38.1	24.2
Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50%
Equity method (loss) earnings, net of tax	$ (0.3)	(0.5)	$ (0.4)
Alpen Food Company South Africa (Proprietary) Limited | Other Assets
Schedule of Equity Method Investments [Line Items]
Equity method investments	3.6	4.1
Other	$ 0.4	$ 0.4
Weetabix East Africa Limited | Post
Schedule of Equity Method Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	50.10%

Business Combinations (Details)

Business Combinations (Details) $ / shares in Units, £ in Millions, shares in Millions, $ in Millions								12 Months Ended
	Apr. 28, 2023 USD ($) shares	Apr. 05, 2022 USD ($)	Apr. 05, 2022 GBP (£)	Jun. 01, 2021 USD ($)	May 27, 2021 USD ($)	Feb. 01, 2021 USD ($)	Jan. 25, 2021 USD ($)	Sep. 30, 2023 USD ($) $ / shares	Sep. 30, 2023 GBP (£)	Sep. 30, 2022 USD ($) $ / shares	Sep. 30, 2021 USD ($) $ / shares
Business Acquisition
Selling, general and administrative expenses								$ 1,078.4		$ 904.7	$ 807
Goodwill								4,574.4		4,349.6
Business Combination, Acquisition Related Costs								17.8		3.2	6.4
Pro forma net sales								7,902.9		7,360.2	5,184.3
Pro forma net earnings from continuing operations								$ 354.2		$ 607	$ 96.9
Pro forma basic earnings from continuing operations per common share | $ / shares								$ 5.78		$ 9.15	$ 1.51
Pro forma diluted earnings from continuing operations per common share | $ / shares								$ 5.36		$ 8.93	$ 1.48
8th Avenue
Business Acquisition
Equity Method Investment, Ownership Percentage								60.50%			60.50%
PL RTE Cereal Business
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price				$ 85
Payments to Acquire Businesses, Gross				$ 88
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net											$ 99.5
Business Combination, Bargain Purchase, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]											Other Operating Income (Expense), Net
Business Combination, Bargain Purchase, Gain Recognized, Amount											$ 11.5
Egg Beaters
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price					$ 50
Payments to Acquire Businesses, Gross					$ 50.6
Almark Foods
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price						$ 52
Payments to Acquire Businesses, Gross						$ 51.3
Business Combination, Cash Received Related to WC Adjustment										$ 2.9
Peter Pan
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price							$ 102
Payments to Acquire Businesses, Gross							$ 103.4
Business Combination, Cash Received Related to WC Adjustment										$ 2
Lacka Foods
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price		$ 32.2
Contingent Consideration		$ 4.6
Business Combination, Contingent Consideration Arrangement, Payments for								$ 1.9
Lacka Foods | Euro Member Countries, Euro
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price | £			£ 24.5
Contingent Consideration | £			3.5
Business Combination, Contingent Consideration Arrangement, Payments for | £									£ 1.5
Lacka Foods | Euro Member Countries, Euro | Maximum
Business Acquisition
Contingent Consideration | £			£ 3.5
Pet Food
Business Acquisition
Payments to Acquire Businesses, Base Purchase Price	$ 700
Payments to Acquire Businesses, Gross	715.5
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net								1,207.5
Other intangible assets								626
Issuance of common stock	$ 492.3
Inventories								205.8
Prepaid expenses and other current assets								0.5
Property								192.9
Deferred Tax Asset								2.7
Other assets								0.3
Other current liabilities								(14.7)
Other Liabilities								(0.2)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net								1,013.3
Goodwill								194.2
Pet Food | TSA Agreement
Business Acquisition
Receivables, net								35.5
Selling, general and administrative expenses								10
Pet Food | Smucker | Common Stock
Business Acquisition
Issuance of common stock, shares | shares	5.4
Pet Food | Customer Relationships
Business Acquisition
Other intangible assets								$ 391
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								18 years	18 years
Pet Food | Trademarks and licensing agreements
Business Acquisition
Other intangible assets								$ 235
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								18 years	18 years

Divestitures and Amounts Held_2

Divestitures and Amounts Held For Sale (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of property and assets held for sale	$ 1.3	$ 18	$ 19.4
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Operating Income (Expense), Net	Other Operating Income (Expense), Net
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		$ 9.4	$ 0.5
Proceeds from sale of business	4.6
Refrigerated Retail | Williamette Egg Farms
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Gain) loss on sale of business		6.3
Disposal Group, Including Discontinued Operation, Assets		62.8
Disposition of Business, Adjustment, Working Capital		0.4
Proceeds from Divestiture of Businesses		56.1
Refrigerated Retail | Williamette Egg Farms | Receivables, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposition of Business, Working Capital Settlement Receivable	$ 1.4	$ 6
Foodservice | Klingerstown Equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Operating Income (Expense), Net
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		$ 9.8
Foodservice | Jefferson City Equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Operating Income (Expense), Net
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		$ 0.4
Weetabix Segment | Corby, United Kingdom facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]			Other Operating Income (Expense), Net
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			$ 0.7
Post Consumer Brands Segment | Clinton, Massachusetts facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]			Other Operating Income (Expense), Net
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			$ 0.1
Post Consumer Brands Segment | Asheboro, North Carolina facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]			Other Operating Income (Expense), Net
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal			$ 0.1

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Goodwill [Line Items]
Goodwill	$ 4,574.4	$ 4,349.6
UNITED KINGDOM
Goodwill [Line Items]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	0.7	0.9	$ 40
Operating Segments
Goodwill [Line Items]
Goodwill (gross)	5,274.4	5,007.4	5,159.4
Accumulated impairment losses	(700)	(657.8)	(657.8)
Goodwill	4,574.4	4,349.6	4,501.6
Goodwill acquired	194.2	14.2
Goodwill, Impairment Loss	(42.2)
Goodwill, Sale of Business		(4.2)
Currency translation adjustment	72.8	$ (162)
Operating Segments | Cheese and dairy
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		6.50%
Operating Segments | Post Consumer Brands Segment
Goodwill [Line Items]
Goodwill (gross)	2,261.1	$ 2,066.8	2,067.1
Accumulated impairment losses	(609.1)	(609.1)	(609.1)
Goodwill	1,652	1,457.7	1,458
Goodwill acquired	194.2	0
Goodwill, Impairment Loss	0
Goodwill, Sale of Business		0
Currency translation adjustment	0.1	(0.3)
Operating Segments | Weetabix Segment
Goodwill [Line Items]
Goodwill (gross)	854.3	781.6	929.4
Accumulated impairment losses	0	0	0
Goodwill	854.3	781.6	929.4
Goodwill acquired	0	13.9
Goodwill, Impairment Loss	0
Goodwill, Sale of Business		0
Currency translation adjustment	72.7	(161.7)
Operating Segments | Foodservice Segment
Goodwill [Line Items]
Goodwill (gross)	1,355.3	1,355.3	1,355
Accumulated impairment losses	0	0	0
Goodwill	1,355.3	1,355.3	$ 1,355
Goodwill acquired	0	0.3
Goodwill, Impairment Loss	0
Goodwill, Sale of Business		0
Currency translation adjustment	0	0
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount			11%
Operating Segments | Refrigerated Retail Segment
Goodwill [Line Items]
Goodwill (gross)	803.7	803.7	$ 807.9
Accumulated impairment losses	(90.9)	(48.7)	(48.7)
Goodwill	712.8	755	$ 759.2
Goodwill acquired	0	0
Goodwill, Impairment Loss	(42.2)
Goodwill, Sale of Business		(4.2)
Currency translation adjustment	$ 0	$ 0
Operating Segments | Refrigerated Retail
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		8.50%
Operating Segments | Weetabix
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	6.40%
Operating Segments | Other Segments
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	13%	10%	15%

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, 2023	Sep. 30, 2022	Sep. 30, 2021
Earnings before Income Taxes and Equity Method Loss [Abstract]
Domestic	$ 397.2	$ 799.9	$ 105.9
Foreign	15.7	95.4	108.1
Earnings before Income Taxes and Equity Method Loss	412.9	895.3	214
Income tax expense	$ 99.7	$ 85.7	$ 58.2
Effective Income Tax Rate Reconciliation, Percent	24.10%	9.60%	27.20%

Income Taxes - Income tax (bene

Income Taxes - Income tax (benefit) expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Current
Federal	$ 96.4	$ 71.1	$ (20.3)
State	21	11.1	(0.2)
Foreign	5.2	13.2	10.5
Current	122.6	95.4	(10)
Deferred
Federal	(10.7)	(9.7)	22.6
State	(11.8)	0	3.4
Foreign	(0.4)	0	42.2
Deferred	(22.9)	(9.7)	68.2
Income tax expense	$ 99.7	$ 85.7	$ 58.2

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosures
Income Tax Reconciliation Threshold for Other Expenses	5%	5%	5%
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed tax at federal statutory rate (21%)	$ 86.7	$ 188	$ 44.9
State income tax, net of effect on federal tax	12.2	10.3	1.7
Non-deductible goodwill impairment charge	8.9	0	0
Non-deductible compensation	7	5.9	5.4
Valuation allowances	1	1.4	2.9
Enacted tax law changes, including the Tax Act	(5.8)	0.9	40
Excess tax benefits for share-based payments	(5.7)	(3.6)	(6.1)
Income tax credits	(2.4)	(1.9)	(1.5)
Enhanced deduction for food donations	(1.6)	(1)	(0.8)
Effective Income Tax Rate Reconciliation, Gain on investment in BellRing	(1.1)	(91.8)	0
Rate differential on foreign income	(0.2)	(10.2)	(11)
Return-to-provision and changes in prior year accruals	(0.1)	(0.5)	(2.8)
Net losses and basis difference attributable to equity method investment	0	(14.1)	(9.2)
Gain on bargain purchase	0	0	(2.4)
Other, net (none in excess of 5% of statutory tax)	0.8	2.3	(2.9)
Income tax expense	$ 99.7	$ 85.7	$ 58.2
UNITED STATES
Income Tax Disclosures
Federal Income Tax Rate	21%	21%	21%

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
State and Local Jurisdiction
Components of Deferred Tax Assets [Abstract]
Disallowed Interest Carryforwards	$ 6
Assets | Noncurrent
Components of Deferred Tax Assets [Abstract]
Disallowed Interest Carryforwards	53.9	$ 55.4
Lease liabilities	49.1	35.8
Derivatives, equity securities and investment adjustments	41	34.9
Net operating loss and credit carryforwards	20.9	24.1
Stock-based and deferred compensation	20.6	19.9
Inventory	16	8.8
Capitalized research and development	11.2	0
Accrued liabilities	10.8	7
Accrued vacation, incentive and severance	10.3	6.2
Basis difference attributable to equity method investment	4.7	4.6
Other items	6.9	5.5
Deferred Tax Assets, Gross, Total	245.4	202.2
Valuation allowance	(36.4)	(35.5)
Total deferred income taxes	209	166.7
Liability | Noncurrent
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(592.2)	(611.4)
Property	(226.1)	(197.6)
ROU assets	(46.2)	(32.9)
Pension and other postretirement benefits	(16.2)	(11.4)
Other items	(2.7)	(1.8)
Deferred Tax Liabilities, Gross	(883.4)	(855.1)
Net Assets | Noncurrent
Components of Deferred Tax Assets [Abstract]
Disallowed Interest Carryforwards	53.9	55.4
Lease liabilities	49.1	35.8
Derivatives, equity securities and investment adjustments	41	34.9
Net operating loss and credit carryforwards	20.9	24.1
Stock-based and deferred compensation	20.6	19.9
Inventory	16	8.8
Capitalized research and development	11.2	0
Accrued liabilities	10.8	7
Accrued vacation, incentive and severance	10.3	6.2
Basis difference attributable to equity method investment	4.7	4.6
Other items	4.2	3.7
Valuation allowance	(36.4)	(35.5)
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(592.2)	(611.4)
Property	(226.1)	(197.6)
ROU assets	(46.2)	(32.9)
Pension and other postretirement benefits	(16.2)	(11.4)
Deferred Tax Liabilities, Gross	(638)	(652.9)
Total deferred tax liabilities, gross	$ (674.4)	$ (688.4)

Income Taxes - Income Taxes Nar

Income Taxes - Income Taxes Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosures
Operating Loss Carryforwards, Limitations on Usage	$ 11,400,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	900,000	$ (6,100,000)	$ 500,000
Undistributed Earnings of Foreign Subsidiaries	$ 106,200,000
Maximum
Income Tax Disclosures
Operating Loss Carryforwards, Expiration	10 years
Domestic Tax Authority
Income Tax Disclosures
Operating Loss Carryforwards	$ 1,700,000
Foreign Tax Authority
Income Tax Disclosures
Operating Loss Carryforwards	5,100,000
State and Local Jurisdiction
Income Tax Disclosures
Operating Loss Carryforwards	11,500,000
Disallowed Interest Carryforwards	6,000,000
State Credit Carryforward
Income Tax Disclosures
Operating Loss Carryforwards	$ 2,600,000
UNITED KINGDOM
Income Tax Disclosures
Newly Enacted Tax Rate	19%
Provisional Tax Rate	25%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 700,000	$ 900,000	$ 40,000,000

Income Taxes - Unrecognized tax

Income Taxes - Unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 11.7	$ 12.5	$ 8.3
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	0.8	0.1	0.3
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	0.4	0	5.2
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(0.1)	(0.9)	(1.3)
Unrecognized Tax Benefits	12.8	11.7	12.5
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	7.6
Decrease in Unrecognized Tax Benefits is Reasonably Possible	5.3
Unrecognized Tax Expense (Benefits), Income Tax Penalties and Interest Expense	0.5	0.1	$ (0.5)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 1.1	$ 0.6

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, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share, Diluted
Net Income (Loss) from continuing operations, net of tax and noncontrolling interest		$ 301.3	$ 735	$ 104.9
Impact of redeemable NCI		(11)	0	11
Net earnings (loss) from continuing operations for basic earnings (loss) per share		312.3	735	93.9
Impact of interest expense, net of tax, related to convertible senior notes		10.9	1.5	0
Net earnings (loss) from continuing operations for diluted earnings (loss) per share		323.2	736.5	93.9
Net earnings from discontinued operations for basic earnings		0	21.6	61.8
Dilutive impact of BellRing net earnings		0	0	(0.1)
Net earnings from discontinued operations for diluted earnings		0	21.6	61.7
Net Earnings (Loss) Available to Common Stockholders, Basic		312.3	756.6	155.7
Net Income (Loss) Available to Common Stockholders, Diluted		$ 323.2	$ 758.1	$ 155.6
Weighted-average shares for basic earnings per share		60	60.9	64.2
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities		5.4	0.7	0
Weighted Average Number of Shares Outstanding, Diluted, Adjustment		7	1.8	1.1
Weighted-average shares for diluted earnings per share		67	62.7	65.3
Earnings (Loss) from Continuing Operations, Per Basic Share		$ 5.21	$ 12.07	$ 1.46
Earnings (Loss) from Continuing Operations, Per Diluted Share		4.82	11.75	1.44
Discontinued Operation, Earnings (Loss) from Discontinued Operation, Net of Tax, Per Basic Share		0	0.35	0.96
Discontinued Operation, Earnings (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share		0	0.34	0.94
Basic earnings per common share (in usd per share)		5.21	12.42	2.42
Diluted earnings per common share (in usd per share)		$ 4.82	$ 12.09	$ 2.38
Stock Options
Earnings Per Share, Diluted
Effect of dilutive securities		0.4	0.3	0.6
Stock Appreciation Rights
Earnings Per Share, Diluted
Effect of dilutive securities		0	0.1	0.1
Restricted Stock
Earnings Per Share, Diluted
Effect of dilutive securities		0.5	0.5	0.3
Earnings-based performance shares
Earnings Per Share, Diluted
Effect of dilutive securities		0.1	0.1	0
Market-based performance shares
Earnings Per Share, Diluted
Effect of dilutive securities		0.6	0.1	0.1

Earnings per Share Antidilutive

Earnings per Share Antidilutive shares excluded from earnings per share (Details) - shares shares in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.1	0.3	0
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	0.1	0

Supplemental Operations State_3

Supplemental Operations Statement and Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Supplemental Operations Statement and Cash Flow Information [Abstract]
Advertising expenses	$ 124.1	$ 93.2	$ 112.3
Research and development expenses	22.9	18.9	21.9
Interest income	(20.9)	(4.4)	(0.6)
Interest paid	300.2	320	348.2
Income taxes paid	114.7	45.8	45.6
Accrued additions to property	$ 37.9	$ 36.4	$ 38.3

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Receivables, net
Trade	$ 451	$ 499.4
Pet Food net receivable (see Note 6)	35.5	0
Income tax receivable	8.3	17.4
Related party	6.9	4.4
Other	13.2	25.3
Gross receivables	514.9	546.5
Allowance for credit losses	(2.5)	(2.3)
Receivables, net	512.4	544.2
Inventories
Raw materials and supplies	155.9	130.9
Work in process	24.4	21.1
Finished products	573.6	361.9
Flocks	36	35.2
Inventories	789.9	549.1
Other Assets
Pension asset	110.3	93.9
Operating ROU assets	176.2	122.9
Other investments	6.1	26.9
Derivative assets	11.3	3
Software implementation costs	18	0
Other	38.1	24.2
Other Assets	360	270.9
Accounts Payable
Trade	339.7	362.1
Book cash overdrafts	1.3	53.3
Related party	13.8	26.1
Other	14	11.2
Accounts payable	368.8	452.7
Current Liabilities
Advertising and promotion	74	47.2
Accrued interest	67	69.5
Accrued compensation	128.2	63.4
Derivative liabilities	16.1	25.9
Operating lease liabilities	22.8	25.5
Accrued freight	16.4	25.1
Other accrued taxes	21.4	19.1
Other	89.5	94.3
Other current liabilities	435.4	370
Other Liabilities
Pension and other postretirement benefit obligations	42.8	45.6
Derivative liabilities	0	49.1
Deferred compensation	36.2	33.1
Operating lease liabilities	169.6	113.7
Other	28.1	25.4
Other Liabilities	$ 276.7	$ 266.9

Derivative Financial Instrume_3

Derivative Financial Instruments and Hedging Derivative Financial Instruments and Hedging Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Derivative [Line Items]
Financing portion of cash paid for rate-lock interest rate swaps	$ (43.5)	$ 0	$ 0
Not Designated as Hedging Instrument | Interest rate swap
Derivative [Line Items]
Derivative, Notional amount of terminated contracts	200
Derivative, Cash Received for Termination	6.7
Derivative, Notional Amount	700	200
Not Designated as Hedging Instrument | Interest rate swap, rate lock swaps
Derivative [Line Items]
Derivative, Notional amount of terminated contracts	849.3	700
Derivative, Cash Settlements paid, net	55.1	17
Derivative, Notional Amount	0	849.3
Not Designated as Hedging Instrument | Interest rate swap, options
Derivative [Line Items]
Derivative, Notional amount of terminated contracts	332.6
Derivative, Cash Settlements paid, net	2.1
Derivative, Notional Amount	$ 0	$ 332.6

Derivative Financial Instrume_4

Derivative Financial Instruments and Hedging (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Derivatives, Fair Value
Asset Derivatives:	$ 25.6	$ 32.9
Liability Derivatives:	16.1	75
Commodity contracts | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	1.2	12.9
Commodity contracts | Other Assets
Derivatives, Fair Value
Asset Derivatives:	0	0.5
Commodity contracts | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	14.1	1.5
Commodity contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	215	145
Energy contracts | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	2.5	13.6
Energy contracts | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	2	1.8
Energy contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	48.9	23.7
Foreign exchange contracts | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	0.1
Foreign exchange contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	3	3.2
Interest rate swap | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	10.6	3.4
Interest rate swap | Other Assets
Derivatives, Fair Value
Asset Derivatives:	11.3	2.5
Interest rate swap | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	22.5
Interest rate swap | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	0	48.1
Interest rate swap | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	700	200
Interest rate swap, rate lock swaps | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	0	849.3
Interest rate swap, options | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	0	332.6
PHPC warrants | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	0	1
PHPC warrants | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	$ 0	$ 16.9

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, 2023	Sep. 30, 2022	Sep. 30, 2021
Derivative Instruments, Loss (Gain) [Line Items]
Income on swaps, net	$ (39.9)	$ (268)	$ (122.8)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	0	(7.1)	(2.3)
Commodity contracts
Derivative Instruments, Loss (Gain) [Line Items]
Year Ended September 30,	$ 28.5	$ (32.2)	$ (11.3)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of goods sold	Cost of goods sold	Cost of goods sold
Energy contracts
Derivative Instruments, Loss (Gain) [Line Items]
Year Ended September 30,	$ 6.7	$ (28.5)	$ (43.1)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of goods sold	Cost of goods sold	Cost of goods sold
Foreign exchange contracts
Derivative Instruments, Loss (Gain) [Line Items]
Year Ended September 30,	$ (0.1)	$ 0.1	$ 0.1
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Selling, general and administrative expenses	Selling, general and administrative expenses	Selling, general and administrative expenses
Interest rate swap
Derivative Instruments, Loss (Gain) [Line Items]
Income on swaps, net	$ (39.9)	$ (268)	$ (122.8)
PHPC warrants
Derivative Instruments, Loss (Gain) [Line Items]
Year Ended September 30,	$ (1)	$ (8.2)	$ (7.7)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)

Derivative Financial Instrume_6

Derivative Financial Instruments and Hedging Derivative and Financial Instruments designated as hedges and Pledged Collateral (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Collateral Already Posted	$ 23.4	$ 2.8

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Mar. 10, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Deferred compensation investment	$ 13	$ 12
Asset Derivatives:	25.6	32.9
Equity securities	0.2	32.1
Investment in BellRing	0	94.8
Assets, Fair Value Disclosure	38.8	171.8
Deferred compensation liabilities	36.8	33.7
Liability Derivatives:	16.1	75
Liabilities, Fair Value Disclosure	52.9	108.7
Return of subsidiary investments held in trust account	345	0	$ 0
Impairment of goodwill	42.2	0	0
(Losses) gains related to assets and liabilities held for sale		9.4	0.5
PHPC Sponsor | PHPC Units
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Return of subsidiary investments held in trust account	40.9
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Deferred compensation investment	13	12
Equity securities	0.2	32.1
Investment in BellRing	0	94.8
Assets, Fair Value Disclosure	13.2	138.9
Deferred compensation liabilities	0	0
Liability Derivatives:	0	1
Liabilities, Fair Value Disclosure	0	1
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Deferred compensation investment	0	0
Asset Derivatives:	25.6	32.9
Equity securities	0	0
Investment in BellRing	0	0
Assets, Fair Value Disclosure	25.6	32.9
Deferred compensation liabilities	36.8	33.7
Liability Derivatives:	16.1	74
Liabilities, Fair Value Disclosure	52.9	107.7
Debt, Fair Value Disclosure	5,491.5	5,171
Level 2 | Senior Notes | 2.50% convertible senior notes maturing in August 2027
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt, Fair Value Disclosure	572.6	566.1
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of assets held-for-sale	0	0.1	$ 0
Proceeds from Sale of Assets and Liabilities Held for Sale	$ (0.1)	(10.3)
(Losses) gains related to assets and liabilities held for sale		9.4
Transfers into assets held for sale		$ 1
BellRing | Post
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Noncontrolling Interest, Ownership Percentage by Parent		3.40%		14.20%

Leases (Details)

Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	8 years	9 years	9 years
Operating Lease, Weighted Average Discount Rate, Percent	5.99%	5.26%	4.70%
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Operating ROU assets	$ 176.2	$ 122.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities	Other current liabilities
Operating lease liabilities	$ 22.8	$ 25.5
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Operating lease liabilities	$ 169.6	$ 113.7
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities	Other Liabilities
Operating Lease, Liability	$ 192.4	$ 139.2
Lessee, Operating Lease, Liability, Payments, Due Year One	33.5
Lessee, Operating Lease, Liability, Payments, Due Year Two	37.1
Lessee, Operating Lease, Liability, Payments, Due Year Three	36.9
Lessee, Operating Lease, Liability, Payments, Due Year Four	32.8
Lessee, Operating Lease, Liability, Payments, Due Year Five	27.1
Lessee, Operating Lease, Liability, Payments, Due after Year Five	75.2
Lessee, Operating Lease, Liability, Payments, Due	242.6
Less: Implied interest	50.2
Operating Lease, Cost	45.8	45.5	$ 40.1
Variable Lease, Cost	5.3	5.2	4.8
Short-term Lease, Cost	7.7	9.4	7.5
Operating Lease, Payments	32.5	29.6	28.4
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 77.7	$ 20.7	$ 33.8
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	53 years

Long Term Debt (Details)

Long Term Debt (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Debt Instrument
Long-term Debt and Capital Lease Obligations, Including Current Maturities	$ 6,049.6	$ 5,969.3
Current portion of long-term debt	1.1	1.1
Unamortized Debt Issuance Expense	42	50.1
Plus: Unamortized premium, net	32.5	38.5
Total long-term debt	6,039	5,956.6
Senior Notes | 2.50% convertible senior notes maturing in August 2027
Debt Instrument
Long-term Debt	575	575
Unamortized Debt Issuance Expense	12.6	15.5
Senior Notes | 4.50% Senior Notes Maturing in September 2031
Debt Instrument
Long-term Debt	1,049.7	1,270.5
Senior Notes | 4.625% Senior Notes Maturing in April 2030
Debt Instrument
Long-term Debt	1,385.4	1,482.2
Senior Notes | 5.50% Senior Notes Maturing in December 2029
Debt Instrument
Long-term Debt	1,235	1,235
Senior Notes | 5.625% Senior Notes Maturing January 2028
Debt Instrument
Long-term Debt	939.9	940.9
Senior Notes | 5.75% Senior Notes Maturing March 2027
Debt Instrument
Long-term Debt	459.3	459.3
Term Loan
Debt Instrument
Long-term Debt	400	0
Municipal Bonds
Debt Instrument
Long-term Debt	$ 5.3	$ 6.4

Long Term Debt - BRBR (Details)

Long Term Debt - BRBR (Details) - USD ($) shares in Millions, $ in Millions			12 Months Ended
	Nov. 25, 2022	Aug. 08, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Nov. 18, 2022
Debt Instrument
Gross Repayments of Long-term debt			$ 349.8	$ 1,661.1	$ 1,698.3
Gross Exchanges of Long-term debt			99.9	1,182.3	$ 0
Post | BellRing
Debt Instrument
Noncontrolling Interest, Common Stock, Transfer	4.6	14.8
Incremental Term Loan | Term Loan
Debt Instrument
Gross Repayments of Long-term debt				840
5.75% Senior Notes Maturing March 2027 | Senior Notes
Debt Instrument
Gross Repayments of Long-term debt				$ 840
Gross Repayments of Long-term debt, percentage				65%
Debt Instrument, Redemption Price, Percentage				102.875%
Gross Exchanges of Long-term debt				$ 0
Second Incremental Term Loan | Term Loan
Debt Instrument
Gross Repayments of Long-term debt				107.7
Loans Payable to Bank				450
Gross Exchanges of Long-term debt				342.3
Third Incremental Term Loan | Term Loan
Debt Instrument
Gross Repayments of Long-term debt			30.1
Loans Payable to Bank						$ 130
Gross Exchanges of Long-term debt			$ 99.9
Third Incremental Term Loan | Term Loan | Secured Overnight Financing Rate
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate			1.50%
First Incremental Term Loan | Term Loan
Debt Instrument
Gross Repayments of Long-term debt				0
Gross Exchanges of Long-term debt				840
Noncash | Incremental Term Loan | Term Loan
Debt Instrument
Gross Repayments of Long-term debt				$ 840

Long Term Debt - Convertible Sr

Long Term Debt - Convertible Sr Notes (Details)	12 Months Ended
	Sep. 30, 2023 USD ($) d $ / shares	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Debt Instrument
Payments of Debt Issuance Costs	$ 3,100,000	$ 26,400,000	$ 16,800,000
Unamortized Debt Issuance Expense	42,000,000	50,100,000
Long-term debt	$ 6,039,000,000	5,956,600,000
Maximum
Debt Instrument
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130%
Minimum
Debt Instrument
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	98%
2.50% convertible senior notes maturing in August 2027 | Senior Notes
Debt Instrument
Debt Instrument, Interest Rate, Stated Percentage	2.50%
Senior Notes	$ 575,000,000
Debt Instrument, Increase, Additional Borrowings	559,100,000
Payments of Debt Issuance Costs	$ 15,900,000
Debt Instrument, Convertible, Conversion Ratio	9.4248
Debt Instrument, Issued, Principal	$ 1,000
Debt Instrument, Convertible, Conversion Price | $ / shares	$ 106.10
Debt Instrument, Convertible, Threshold Consecutive Trading Days | d	5
Debt Instrument, Convertible, Threshold Trading Days | d	10
Unamortized Debt Issuance Expense	$ 12,600,000	15,500,000
Long-term debt	$ 562,400,000	$ 559,500,000

Long Term Debt - Other Sr Notes

Long Term Debt - Other Sr Notes (Details) - USD ($)	3 Months Ended					12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2021
Debt Instrument
Payments of Debt Issuance Costs						$ 3,100,000	$ 26,400,000	$ 16,800,000
5.75% Senior Notes Maturing March 2027 | Senior Notes
Debt Instrument
Senior Notes					$ 750,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.75%
Debt Instrument, Increase, Additional Borrowings					739,500,000
Payments of Debt Issuance Costs					$ 10,500,000
Long-term Debt						$ 459,300,000	459,300,000
Additional Issuance of 5.75% Senior Notes Maturing in March 2027 | Senior Notes
Debt Instrument
Senior Notes				$ 750,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.75%
Debt Instrument, Increase, Additional Borrowings				784,000,000
Payments of Debt Issuance Costs				$ 7,200,000
Debt Instrument, Issuance Price, Percentage of Par Value				105.50%
5.625% Senior Notes Maturing January 2028 | Senior Notes
Debt Instrument
Senior Notes			$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.625%
Debt Instrument, Increase, Additional Borrowings			990,600,000
Payments of Debt Issuance Costs			$ 9,400,000
Long-term Debt						$ 939,900,000	$ 940,900,000
5.50% Senior Notes Maturing in December 2029 | Senior Notes
Debt Instrument
Senior Notes		$ 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
Long-term Debt						$ 1,235,000,000	$ 1,235,000,000
Additional 5.50% Senior Notes Maturing in December 2029 | Senior Notes
Debt Instrument
Debt Instrument, Interest Rate, Stated Percentage							5.50%
Debt Instrument, Increase, Additional Borrowings							$ 514,000,000
Payments of Debt Issuance Costs							$ 3,500,000
Debt Instrument, Issuance Price, Percentage of Par Value							103.50%
Long-term Debt							$ 500,000,000
Original Issuance of 4.625% Senior Notes Maturing in April 2030 | Senior Notes
Debt Instrument
Debt Instrument, Increase, Additional Borrowings									$ 1,241,000,000
Payments of Debt Issuance Costs									9,000,000
Long-term Debt	$ 1,250,000,000								1,250,000,000
4.625% Senior Notes Maturing in April 2030 | Senior Notes
Debt Instrument
Debt Instrument, Interest Rate, Stated Percentage						4.625%
Debt Instrument, Issuance Price, Percentage of Par Value							87%
Long-term Debt						$ 1,385,400,000	$ 1,482,200,000
Additional Issuance of 4.625% Senior Notes Maturing in April 2030 | Senior Notes
Debt Instrument
Debt Instrument, Increase, Additional Borrowings									417,500,000
Payments of Debt Issuance Costs									4,500,000
Debt Instrument, Issuance Price, Percentage of Par Value	105.50%
Long-term Debt	$ 400,000,000								$ 400,000,000
4.50% Senior Notes Maturing in September 2031 | Senior Notes
Debt Instrument
Senior Notes										$ 1,800,000,000
Debt Instrument, Interest Rate, Stated Percentage						4.50%
Debt Instrument, Increase, Additional Borrowings								1,783,200,000
Payments of Debt Issuance Costs								$ 16,800,000
Debt Instrument, Issuance Price, Percentage of Par Value							86%
Long-term Debt						$ 1,049,700,000	$ 1,270,500,000

Long Term Debt - Credit Agreeme

Long Term Debt - Credit Agreement (Details) $ in Millions	12 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Debt Instrument
Payments of Debt Issuance Costs	$ 3.1	$ 26.4	$ 16.8
Debt Covenant, Leverage Ratio	4.25
Revolving Credit Facility
Debt Instrument
Line of Credit Facility, Current Borrowing Capacity	$ 750
Letters of Credit Outstanding, Amount	19.7	19.7
Line of Credit Facility, Remaining Borrowing Capacity	730.3	730.3
Payments of Financing Costs		$ 0.4
Debt Covenant, Maximum Undischarged Judgments	$ 100
Revolving Credit Facility | High-End Ratio
Debt Instrument
Debt Covenant, Leverage Ratio	3
Revolving Credit Facility | Low-End Ratio
Debt Instrument
Debt Covenant, Leverage Ratio	1.50
Revolving Credit Facility | Maximum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.375%
Revolving Credit Facility | Minimum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Revolving Credit Facility | Federal Funds
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	0.50%
Revolving Credit Facility | One-Month adjusted term SOFR
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	1%
Revolving Credit Facility | Adjusted term SOFR | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	2%
Revolving Credit Facility | Adjusted term SOFR | Median
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	1.75%
Revolving Credit Facility | Adjusted term SOFR | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	1.50%
Revolving Credit Facility | Base Rate | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	1%
Revolving Credit Facility | Base Rate | Median
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	0.75%
Revolving Credit Facility | Base Rate | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	0.50%
Line of Credit
Debt Instrument
Line of Credit Facility, Current Borrowing Capacity	$ 75
Credit Agreement
Debt Instrument
Payments of Debt Issuance Costs				$ 3.6

Long Term Debt - Term Loan (Det

Long Term Debt - Term Loan (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 26, 2023	Sep. 30, 2023
Debt Instrument
Percentage of Consolidate Cash Flow		50%
Minimum
Debt Instrument
Percentage of Consolidate Cash Flow		0%
Maximum
Debt Instrument
Percentage of Consolidate Cash Flow		25%
Fourth Incremental Term Loan | Term Loan
Debt Instrument
Loans Payable to Bank	$ 400
Debt Issuance Cost, Gross, Noncurrent	$ 1.9
Debt Instrument, Interest Rate, Effective Percentage		7.67%
Fourth Incremental Term Loan | Term Loan | Secured Overnight Financing Rate
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	2.25%
Fourth Incremental Term Loan | Term Loan | Base Rate
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	1.25%

Long Term Debt - Repayments (De

Long Term Debt - Repayments (Details) - USD ($) $ in Millions		12 Months Ended
	Jul. 26, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt		$ 349.8	$ 1,661.1	$ 1,698.3
Gross Exchanges of Long-term debt		99.9	1,182.3	0
Estimated future interest payments on debt		1,367.1
Estimated future interest payments on debt, next twelve months		305.9
Long-Term Debt, Maturity, Year One		1.1
Long-Term Debt, Maturity, Year Two		1.2
Long-Term Debt, Maturity, Year Three		401.2
Long-Term Debt, Maturity, Year Four		1,035.6
Long-Term Debt, Maturity, Year Five		$ 940.4
Debt Covenant, Leverage Ratio		4.25
Debt Covenant, Percentage of Revolving Credit Commitments		30%
Debt Covenant, interest coverage ratio		2
Maximum
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt			450
Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums		$ (42.9)	(73.7)	74.3
Write-off of Unamortized Debt Discount/(Premium)		(0.9)	(15.3)	0
Write off of Deferred Debt Issuance Cost		3.3	16.4	18.9
Municipal Bonds
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt		1.1	1.1	1
Gross Exchanges of Long-term debt		0	0	0
Municipal Bonds | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums		0	0	0
Write-off of Unamortized Debt Discount/(Premium)		0	0	0
Write off of Deferred Debt Issuance Cost		0	0	0
Third Incremental Term Loan | Term Loan
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt		30.1
Gross Exchanges of Long-term debt		99.9
Third Incremental Term Loan | Term Loan | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums		0
Write-off of Unamortized Debt Discount/(Premium)		0
Write off of Deferred Debt Issuance Cost		1.1
4.625% Senior Notes Maturing in April 2030 | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	$ 139.8	96.8	167.8
Gross Exchanges of Long-term debt		$ 0	$ 0
Debt Instrument, Issuance Price, Percentage of Par Value			87%
Debt Issuance, Tender Premium, Percentage of Par Value			5%
Gross Repayments of Long-term debt, percentage			8%
Debt Instrument, Interest Rate, Stated Percentage		4.625%
4.625% Senior Notes Maturing in April 2030 | Senior Notes | Maximum
Extinguishment of Debt [Line Items]
Debt Instrument, Issuance Price, Percentage of Par Value			88%
4.625% Senior Notes Maturing in April 2030 | Senior Notes | Minimum
Extinguishment of Debt [Line Items]
Debt Instrument, Issuance Price, Percentage of Par Value			81%
4.625% Senior Notes Maturing in April 2030 | Senior Notes | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums		$ (11.4)	$ (21.9)
Write-off of Unamortized Debt Discount/(Premium)		(0.9)	(1.8)
Write off of Deferred Debt Issuance Cost		0.5	1.1
4.50% Senior Notes Maturing in September 2031 | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt	$ 381.8	220.8	529.5
Gross Exchanges of Long-term debt		$ 0	$ 0
Debt Instrument, Issuance Price, Percentage of Par Value			86%
Debt Issuance, Tender Premium, Percentage of Par Value			5%
Gross Repayments of Long-term debt, percentage			22%
Debt Instrument, Interest Rate, Stated Percentage		4.50%
4.50% Senior Notes Maturing in September 2031 | Senior Notes | Maximum
Extinguishment of Debt [Line Items]
Debt Instrument, Issuance Price, Percentage of Par Value			87%
4.50% Senior Notes Maturing in September 2031 | Senior Notes | Minimum
Extinguishment of Debt [Line Items]
Debt Instrument, Issuance Price, Percentage of Par Value			80%
4.50% Senior Notes Maturing in September 2031 | Senior Notes | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums		$ (31.5)	$ (74.7)
Write-off of Unamortized Debt Discount/(Premium)		0	0
Write off of Deferred Debt Issuance Cost		$ 1.7	6
5.50% Senior Notes Maturing in December 2029 | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt			15
Gross Exchanges of Long-term debt			$ 0
Debt Instrument, Interest Rate, Stated Percentage		5.50%	5.50%
5.50% Senior Notes Maturing in December 2029 | Senior Notes | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums			$ (1.2)
Write-off of Unamortized Debt Discount/(Premium)			(0.2)
Write off of Deferred Debt Issuance Cost			0.1
5.75% Senior Notes Maturing March 2027 | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt			840
Gross Exchanges of Long-term debt			$ 0
Gross Repayments of Long-term debt, percentage			65%
Debt Instrument, Interest Rate, Stated Percentage		5.75%
5.75% Senior Notes Maturing March 2027 | Senior Notes | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums			$ 24.1
Write-off of Unamortized Debt Discount/(Premium)			(13.3)
Write off of Deferred Debt Issuance Cost			5
First Incremental Term Loan | Term Loan
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt			0
Gross Exchanges of Long-term debt			840
First Incremental Term Loan | Term Loan | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums			0
Write-off of Unamortized Debt Discount/(Premium)			0
Write off of Deferred Debt Issuance Cost			3.5
Second Incremental Term Loan | Term Loan
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt			107.7
Gross Exchanges of Long-term debt			342.3
Second Incremental Term Loan | Term Loan | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums			0
Write-off of Unamortized Debt Discount/(Premium)			0
Write off of Deferred Debt Issuance Cost			0.7
5.00% Senior Notes Maturing in August 2026 | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt				1,697.3
Gross Exchanges of Long-term debt				0
5.00% Senior Notes Maturing in August 2026 | Senior Notes | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums				74.3
Write-off of Unamortized Debt Discount/(Premium)				0
Write off of Deferred Debt Issuance Cost				$ 18.9
4.50% and 4.625% Senior Notes | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt			450
Payment of tender fees			$ 1.7
2.50% convertible senior notes maturing in August 2027 | Senior Notes
Extinguishment of Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.50%
Long-Term Debt, Maturity, Year Five		$ 575
5.625% Senior Notes Maturing January 2028 | Senior Notes
Extinguishment of Debt [Line Items]
Gross Repayments of Long-term debt		1
Gross Exchanges of Long-term debt		$ 0
Debt Instrument, Interest Rate, Stated Percentage		5.625%
5.625% Senior Notes Maturing January 2028 | Senior Notes | Loss on extinguishment of debt, net
Extinguishment of Debt [Line Items]
Payment (Proceeds) for debt discounts and premiums		$ 0
Write-off of Unamortized Debt Discount/(Premium)		0
Write off of Deferred Debt Issuance Cost		$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions		12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2023 USD ($) defendant plaintiff_group	Sep. 30, 2022 USD ($)	Sep. 30, 2021
Bob Evans Farms
Loss Contingencies [Line Items]
Lease Guarantee, Number of Properties		130		143
Current annual rent of guaranteed leases		$ 13.1
Lease Guarantee, Interest rate increase		1.50%
Lease Guarantee, Remaining Lease Term		14 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
Selling, general and administrative expenses | Michael Foods
Loss Contingencies [Line Items]
Litigation Settlement, Expense			$ 13.8

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, 2023	Sep. 30, 2022	Sep. 30, 2021
Amounts recognized in assets or liabilities [Abstract]
Pension asset	$ 110.3	$ 93.9
Other liabilities	$ (42.8)	$ (45.6)
UNITED STATES
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	6.01%	5.62%
CANADA
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	5.67%	5.12%
Rate of compensation increase	2.75%	2.75%
Pension Benefits | UNITED STATES
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	6.06%	5.65%
Rate of compensation increase	3%	3%
Pension Benefits | North America
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	$ 95.5	$ 133.3
Service cost	2.2	4.3	$ 3.9
Interest cost	5.3	3.5	3.2
Plan participants' contributions	0.3	0.4
Actuarial (gain) loss	(5.4)	(38.9)
Benefits Paid	(5.4)	(5.9)
Currency translation	0.1	(1.2)
Benefit obligation at end of period	$ 92.6	$ 95.5	$ 133.3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	$ 102.9	$ 136.6
Actual return on plan assets	10.1	(27.1)
Employer contributions	0.1	0.4
Plan participants' contributions	0.3	0.4
Benefits Paid	(5.4)	(5.9)
Currency translation	0.2	(1.5)
Other	0	0
Fair value of plan assets at end of period	108.2	102.9	$ 136.6
Defined benefit plan, funded status of plan [Abstract]
Funded status	15.6	7.4
Amounts recognized in assets or liabilities [Abstract]
Pension asset	15.9	7.7
Other liabilities	(0.3)	(0.3)
Net amount recognized	15.6	7.4
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	(2.7)	5
Prior service cost (credit)	0.4	0.6
Total	(2.3)	5.6
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	91.8	94.6
Pension Benefits | Other international
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	421.1	821.3
Service cost	0	0
Interest cost	23.3	15.7	15.2
Plan participants' contributions	0	0
Actuarial (gain) loss	(37.5)	(251.6)
Benefits Paid	(25.9)	(28.4)
Currency translation	41	(135.9)
Benefit obligation at end of period	$ 422	$ 421.1	$ 821.3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	$ 507.3	$ 970.9
Actual return on plan assets	(14.3)	(273)
Employer contributions	0	0
Plan participants' contributions	0	0
Benefits Paid	(25.9)	(28.4)
Currency translation	49.4	(162.1)
Other	(0.1)	(0.1)
Fair value of plan assets at end of period	516.4	507.3	$ 970.9
Defined benefit plan, funded status of plan [Abstract]
Funded status	94.4	86.2
Amounts recognized in assets or liabilities [Abstract]
Pension asset	94.4	86.2
Other liabilities	0	0
Net amount recognized	94.4	86.2
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	47.7	40.2
Prior service cost (credit)	10.3	10.7
Total	$ 58	$ 50.9
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	5.67%	5.15%
Rate of compensation increase	3.02%	3.85%
Pension Benefits | CANADA
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	5.68%	5.12%
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	$ 422	$ 418.9
Other Benefits | North America
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	48.3	66.5
Service cost	0.3	0.5	0.5
Interest cost	2.5	1.5	1.5
Actuarial (gain) loss	(3)	(17.4)
Benefits Paid	(2.3)	(2.3)
Currency translation	0	(0.5)
Benefit obligation at end of period	$ 45.8	$ 48.3	$ 66.5
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	$ 0
Employer contributions	2.3	$ 2.3
Benefits Paid	(2.3)	(2.3)
Fair value of plan assets at end of period	0	0
Defined benefit plan, funded status of plan [Abstract]
Funded status	(45.8)	(48.3)
Amounts recognized in assets or liabilities [Abstract]
Other current liabilities	(3.3)	(3)
Other liabilities	(42.5)	(45.3)
Net amount recognized	(45.8)	(48.3)
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	(11.7)	(9.2)
Prior service cost (credit)	(0.7)	(5.4)
Total	$ (12.4)	$ (14.6)

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, 2023	Sep. 30, 2022	Sep. 30, 2021
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	$ (3.4)	$ 24	$ 8.1
Pension Benefits | UNITED STATES
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	5.65%	3.05%	3.01%
Rate of compensation increase	3%	3%	3%
Expected return on plan assets	6.50%	5.75%	5.40%
Pension Benefits | Other international
Components of net periodic benefit cost [Abstract]
Service cost	$ 0	$ 0
Interest cost	23.3	15.7	$ 15.2
Expected return on plan assets	(30.8)	(24.8)	(24.9)
Recognized net actuarial (gain) loss	0.1	0	0
Recognized prior service cost	0.4	0.4	0.5
Net periodic benefit (income) cost	$ (7)	$ (8.7)	$ (9.2)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	5.15%	2.05%	1.73%
Rate of compensation increase	3.85%	3.45%	2.65%
Expected return on plan assets	5.63%	2.73%	2.38%
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	$ 7.6	$ 46.2	$ 26.4
Recognized gain (loss)	(0.1)	0	0
Recognized prior service cost	(0.4)	(0.4)	(0.5)
Total recognized in other comprehensive income or loss (before tax effects)	7.1	45.8	25.9
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	0
Pension Benefits | North America
Components of net periodic benefit cost [Abstract]
Service cost	2.2	4.3	3.9
Interest cost	5.3	3.5	3.2
Expected return on plan assets	(7.5)	(7)	(6.4)
Recognized net actuarial (gain) loss	(0.2)	1.6	2.4
Recognized prior service cost	0.1	0.1	0.1
Net periodic benefit (income) cost	$ (0.1)	$ 2.5	$ 3.2
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	$ (8)	$ (4.7)	$ (14.5)
Recognized gain (loss)	0.2	(1.6)	(2.4)
Prior Service Cost	0	0	0.5
Recognized prior service cost	(0.1)	(0.1)	(0.1)
Total recognized in other comprehensive income or loss (before tax effects)	(7.9)	$ (6.4)	$ (16.5)
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0.3
Pension Benefits | CANADA
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	5.12%	3.32%	2.71%
Rate of compensation increase	2.75%	2.75%	2.75%
Expected return on plan assets	5.75%	5.25%	5.25%
Other Benefits | UNITED STATES
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	5.62%	2.89%	2.79%
Other Benefits | North America
Components of net periodic benefit cost [Abstract]
Service cost	$ 0.3	$ 0.5	$ 0.5
Interest cost	2.5	1.5	1.5
Recognized net actuarial (gain) loss	(0.5)	0.6	1.1
Recognized prior service cost	(4.7)	(4.6)	(4.7)
Net periodic benefit (income) cost	$ (2.4)	$ (2)	$ (1.6)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss	$ (3)	$ (17.5)	$ (4.3)
Recognized gain (loss)	0.5	(0.6)	(1.1)
Recognized prior service cost	4.7	4.6	4.7
Total recognized in other comprehensive income or loss (before tax effects)	$ 2.2	$ (13.5)	$ (0.7)
Other Benefits | CANADA
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	5.12%	3.45%	2.78%
Rate of compensation increase	2.75%	2.75%	2.75%

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, 2023	Sep. 30, 2022	Sep. 30, 2021
Other international
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Actual allocations, index funds	23.70%	20.20%
Pension plan's assets at fair value	$ 516.4	$ 507.3	$ 970.9
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	389.4	409.8
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	127	97.5
Other international | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	389.4	409.8
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	389.4	409.8
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Other international | 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
Other international | Fixed Income Funds and Bonds
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	71.60%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	75.20%	78.80%
Other international | Fixed Income Funds and Bonds | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 280.4	$ 321.3
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Other international | 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
Other international | 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	280.4	321.3
Other international | 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	$ 107.8	$ 78.5
Other international | Liability Hedging Instruments
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	27.70%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	21.40%	18.70%
Other international | Liability Hedging Instruments | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 91.6	$ 77.9
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
Other international | 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
Other international | 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	91.6	77.9
Other international | 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	$ 19.2	$ 16.9
Other international | Real assets
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.60%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		0.40%
Other international | 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
Other international | 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
Other international | 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	$ 2.1
Other international | Cash and Cash Equivalents
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.10%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	3.40%	2.10%
Other international | Cash and Cash Equivalents | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 17.4	$ 10.6
Other international | Cash and Cash Equivalents | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Other international | 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	$ 17.4	$ 10.6
North America
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Actual allocations, index funds	96.80%	91.90%
Pension plan's assets at fair value	$ 108.2	$ 102.9	$ 136.6
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	21.2	24.9
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	87	78
North America | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	4.1	8.9
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	4.1	8.9
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	17.1	16
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	17.1	16
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	57.70%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	64.70%	54.50%
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	11.9	11
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
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	11.9	11
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	$ 58.1	$ 45.1
North America | Fixed Income Funds and Bonds
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	38%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	30.20%	33.90%
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	5.2	5
Defined Benefit Plan, Plan Assets, Amount Measured at Net Asset Value	0	0
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	5.2	5
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	$ 27.6	$ 29.9
North America | Real assets
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.30%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.30%	2.90%
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	$ 1.3	$ 3
North America | Cash and Cash Equivalents
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	1%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	3.80%	8.70%
North America | Cash and Cash Equivalents | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 4.1	$ 8.9
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	$ 4.1	$ 8.9

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, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5%	5%
Participants Over and Under 65
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	6.50%	6.30%
CANADA | Participants Over and Under 65
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	4.50%	4.50%

Pension and Other Postretirem_7

Pension and Other Postretirement Benefits - Expected Future Benefit Payments and Related Federal Subsidy Receipts (Details) $ in Millions	Sep. 30, 2023 USD ($)
Pension Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Year 1	$ 26.7
Year 2	27.6
Year 3	28.9
Year 4	30.1
Year 5	30.7
Year 6 and thereafter	172.2
Other Benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Year 1	3.5
Year 2	3.5
Year 3	3.5
Year 4	3.5
Year 5	3.5
Year 6 and thereafter	17.8
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 and thereafter	$ 1.1

Pension and Other Postretirem_8

Pension and Other Postretirement Benefits - Defined contribution plan expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Retirement Benefits [Abstract]
401K Matching Contributions	$ 21.4	$ 19.6	$ 19.9

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans Narrative (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Jan. 27, 2022
Share-based Payment Award [Line Items]
Matching contribution on Director Deferred Compensation	33.30%
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	$ 77.8	$ 66.4	$ 49.7
Recognized deferred tax beneft	10.5	$ 9.1	$ 5.8
Compensation cost related to nonvested awards not yet recognized	$ 77.2
Awards not yet recognized. weighted average period to be recognized	1 year 3 months 18 days
2021 Long-Term Incentive Plan
Restricted Stock Awards [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized				2.4

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, 2023	Sep. 30, 2022	Sep. 30, 2021
Post Cash Settled
Stock Appreciation Rights
Total Share-based Liabilities Paid	$ 1.4	$ 1.1	$ 1.1
Granted	0
Forfeited	0
Post Stock Settled
Stock Appreciation Rights
Outstanding	51,898	81,554
Granted	0
Exercised	(29,656)
Forfeited	0
Expired	0
Vested And Expected To Vest	51,898
Exercisable	51,898
Outstanding, Weighted Average Exercise Price	$ 36.35	$ 33.42
Granted, Weighted Average Exercise Price
Exercised, Weighted Average Exercise Price	28.28
Forfeited, Weighted Average Exercise Price
Expired, Weighted Average Exercise Price
Vested And Expected To Vest, Weighted Average Exercise Price	36.35
Exercisable, Weighted Average Exercise Price	$ 36.35
Outstanding, Weighted Average Remaining Contractual Term	1 year 2 months 23 days
Vested And Expected To Vest, Outstanding, Weighted Average Remaining Contractual Term	1 year 2 months 23 days
Exercisable, Weighted Average Remaining Contractual Term	1 year 2 months 23 days
Outstanding, Intrinsic Value	$ 2.6
Vested And Expected To Vest, Outstanding, Aggregate Intrinsic Value	2.6
Exercisable, Aggregate Intrinsic Value	2.6
Exercised, Total Intrinsic Value	$ 1.9	$ 3	$ 3.2

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans - Stock Option award activity (Details) - Post Stock Options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Share-based Payment Award [Line Items]
Outstanding	748,708	1,011,315
Granted	0
Exercised	(262,607)
Forfeited	0
Expired	0
Vested and Expected to Vest	748,708
Exercisable	748,708
Outstanding, Weighted Average Exercise Price	$ 51.96	$ 48.75
Granted, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	39.57
Forfeited, Weighted Average Exercise Price	0
Expired, Weighted Average Exercise Price	0
Vested and Expected to Vest, Weighted Average Exercise Price	51.96
Exercisable, Weighted Average Exercise Price	$ 51.96
Outstanding, Weighted Average Remaining Contractual Term	3 years 7 months 17 days
Vested and Expected to Vest, Weighted Average Remaining Contractual Term	3 years 7 months 17 days
Exercisable, Weighted Average Remaining Contractual Term	3 years 7 months 17 days
Outstanding, Intrinsic Value	$ 25.3
Vested and Expected to Vest, Aggregate Intrinsic Value	25.3
Exercisable, Intrinsic Value	25.3
Exercised, Total Intrinsic Value	14.1	$ 14.1	$ 46.4
Proceeds from Stock Options Exercised	$ 3.9	$ 4.9	$ 7.6

Stock-Based Compensation Plan_5

Stock-Based Compensation Plans - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Post Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	1,060,232	1,348,806
Granted	526,035
Vested	(763,124)
Forfeited	(51,485)
Grant date value per share	$ 79.99	$ 68.38	$ 97.23
Granted, Weighted Average Exercise Price	90.85
Vested, Weighted Average Exercise Price	67.34
Forfeited, Weighted Average Exercise Price	$ 74.06
Fair value of restricted stock awards vested	$ 68.9	$ 35.1	$ 49.8
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	$ 34.68
Nonvestsed restricted stock awards	13,048	29,063
Granted	0
Vested	(16,015)
Forfeited	0
Grant date value per share	$ 34.68	$ 34.68
Granted, Weighted Average Exercise Price	0
Vested, Weighted Average Exercise Price	34.68
Forfeited, Weighted Average Exercise Price	$ 0
Total Share-based Liabilities Paid	$ 1.4	$ 1.1	$ 1.1

Stock-Based Compensation Plan_6

Stock-Based Compensation Plans Performance Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Minimum
Share-based Payment Award [Line Items]
Total Award Range	0%
Maximum
Share-based Payment Award [Line Items]
Total Award Range	260%
Earnings-Based Restricted Stock Units | Post Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	259,542	272,427
Granted	142,939
Vested	(148,531)
Forfeited	(7,293)
Grant date value per share	$ 83.20	$ 70.46	$ 98.33
Granted, Weighted Average Exercise Price	94.09
Vested, Weighted Average Exercise Price	70.36
Forfeited, Weighted Average Exercise Price	$ 83.83
Fair value of restricted stock awards vested	$ 14.1
Market-based performance shares | Post Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	494,105	374,402
Granted	142,843
Vested	0
Forfeited	(23,140)
Grant date value per share	$ 120.69	$ 106.10
Granted, Weighted Average Exercise Price	156.05	$ 163.63	$ 152.58
Vested, Weighted Average Exercise Price	0
Forfeited, Weighted Average Exercise Price	$ 102.95
Expected Term	3 years	3 years	3 years
Expected Volatility Rate	29.10%	27.70%	28.30%
Risk Free Interest Rate	4.10%	0.90%	0.20%
Expected Dividend Rate	0%	0%	0%
Fair value of restricted stock awards vested		$ 6.6	$ 3.9

Shareholders' Equity (Details)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		5 Months Ended	7 Months Ended	12 Months Ended
	Apr. 28, 2023	Mar. 10, 2022	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Class of Stock [Line Items]
Cash received from share repurchase contracts				$ 0	$ 0	$ 47.5
Pet Food
Class of Stock [Line Items]
Issuance of common stock	$ 492.3
Common Stock
Class of Stock [Line Items]
Treasury Stock, Shares, Acquired				4.4	4.9	4
Treasury Stock Acquired, Average Cost Per Share				$ 87.13	$ 90.02	$ 98.37
Purchases of treasury stock				$ 387.1	$ 439	$ 393.7
Payments of accrued repurchases of common stock					$ 4	$ 7.4
Issuance of common stock, shares				6.1
Common Stock
Class of Stock [Line Items]
Treasury Stock Acquired, Average Cost Per Share		$ 103.79	$ 81.53
Common Stock | Smucker | Pet Food
Class of Stock [Line Items]
Issuance of common stock, shares	5.4

Segments (Details)

Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Net Sales	$ 6,991	$ 5,851.2	$ 4,980.7
Operating Profit	598.9	415.6	487.7
Impairment of goodwill	42.2	0	0
Interest expense, net	279.1	317.8	332.6
(Gain) loss on extinguishment of debt, net	(40.5)	(72.6)	93.2
Income on swaps, net	(39.9)	(268)	(122.8)
Gain on investment in BellRing	(5.1)	(437.1)	0
Earnings before income taxes and equity method loss	412.9	895.3	214
Property, Plant and Equipment, Additions	311.1	274.8	190.9
Depreciation and amortization	407.1	380.2	$ 366.5
Assets	11,646.7	11,308
Noncash
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Additions	$ 8.1	$ 19.5
Customer Concentration Risk | Revenue Benchmark | Walmart
Segment Reporting Information [Line Items]
Entity-Wide Revenue, Major Customer, Percentage	17.30%	14.40%	15.90%
Non-US
Segment Reporting Information [Line Items]
Sales to Foreign Countries as a Percentage of Total Net Sales	11%	12.50%	14.30%
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries	$ 280.9	$ 253.6
Revenues from External Customers and Long-Lived Assets [Line Items]
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries	$ 280.9	$ 253.6
Canada as a percentage of Non-US
Segment Reporting Information [Line Items]
Sales to Foreign Countries as a Percentage of Total Net Sales	54%	52.90%	54.60%
Operating Segments
Segment Reporting Information [Line Items]
Net Sales	$ 6,991	$ 5,851.2	$ 4,980.7
Operating Profit	871.4	632.2	569.6
Depreciation and amortization	398	376.5	362.5
Operating Segments | Post Consumer Brands Segment
Segment Reporting Information [Line Items]
Net Sales	3,033.1	2,242.7	1,915.3
Operating Profit	378.8	314.6	316.6
Property, Plant and Equipment, Additions	112.8	91.2	81.2
Depreciation and amortization	157.3	133.1	122
Assets	4,782.2	3,529.1
Operating Segments | Weetabix Segment
Segment Reporting Information [Line Items]
Net Sales	512.1	477.3	477.5
Operating Profit	73.9	109.5	115.4
Property, Plant and Equipment, Additions	30.1	26.7	19.6
Depreciation and amortization	35.9	37.5	39
Assets	1,737.8	1,591.3
Operating Segments | Foodservice and Refrigerated Retail
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Additions	144	136.1	89.7
Assets	4,921.6	5,022.7
Operating Segments | Foodservice Segment
Segment Reporting Information [Line Items]
Net Sales	2,425.9	2,095	1,615.6
Operating Profit	349.5	151	61.7
Depreciation and amortization	128.7	127.5	126
Operating Segments | Refrigerated Retail Segment
Segment Reporting Information [Line Items]
Net Sales	1,019.7	1,036.6	974.5
Operating Profit	69.2	57.1	75.9
Depreciation and amortization	76.1	78.4	75.5
Corporate, Non-Segment
Segment Reporting Information [Line Items]
General corporate expenses and other	222.7	196.8	52.6
Property, Plant and Equipment, Additions	24.2	20.8	0.4
Depreciation and amortization	9.1	3.7	4
Assets	205.1	1,164.9
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Sales	0.2	(0.4)	(2.2)
Cereal | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	2,730.8	2,595	2,333.3
Eggs and egg products | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	2,304	2,026.1	1,556.1
Side dishes (including potato products) | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	732	652.4	575
Pet Food | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	679.8	0	0
Cheese and dairy | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	191.5	214.3	223
Sausage | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	163.6	171.2	165.9
Nut butters | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	100.5	111.7	58.7
Protein-based products | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	34.1	12.9	0
Other | Operating Segments
Segment Reporting Information [Line Items]
Net Sales	55.4	68.5	70.9
Product Eliminations
Segment Reporting Information [Line Items]
Net Sales	$ (0.7)	$ (0.9)	$ (2.2)

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Oct. 07, 2023 USD ($)
Subsequent Event | Perfection
Subsequent Event [Line Items]
Payments to Acquire Businesses, Base Purchase Price	$ 235