Post (POST) 10-K 17 Nov 17 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2017	Nov. 13, 2017	Mar. 31, 2017
Document Information
Entity Registrant Name	Post Holdings, Inc.
Entity Central Index Key	1,530,950
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		66,120,127
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 5,522,477,167

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Net Sales	$ 5,225.8	$ 5,026.8	$ 4,648.2
Cost of goods sold	3,651.7	3,479.4	3,473.8
Gross Profit	1,574.1	1,547.4	1,174.4
Selling, general and administrative expenses	867.4	839.7	734.1
Amortization of intangible assets	159.1	152.6	141.7
Impairment of goodwill and other intangible assets	26.5	0	60.8
Other operating expenses, net	0.8	9.4	25.1
Operating Profit	520.3	545.7	212.7
Interest expense, net	314.8	306.5	257.5
Loss on extinguishment of debt, net	222.9	86.4	30
Other (income) expense, net	(91.8)	182.9	92.5
Earnings (Loss) before Income Taxes	74.4	(30.1)	(167.3)
Income tax expense (benefit)	26.1	(26.8)	(52)
Net Earnings (Loss) Including Noncontrolling Interest	48.3	(3.3)	(115.3)
Less: Net loss attributable to noncontrolling interest	0	0	0
Net Earnings (Loss)	48.3	(3.3)	(115.3)
Preferred stock dividends	(13.5)	(25.1)	(17)
Net Earnings (Loss) Available to Common Shareholders	$ 34.8	$ (28.4)	$ (132.3)
(Loss) Earnings per share:
Basic (loss) earnings per common share	$ 0.51	$ (0.41)	$ (2.33)
Diluted (loss) earnings per common share	$ 0.50	$ (0.41)	$ (2.33)
Weighted-Average Common Shares Outstanding:
Weighted-average shares for basic (loss) earnings per share	67.8	68.8	56.7
Weighted-average shares for diluted earnings (loss) per share	69.9	68.8	56.7

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 48.3	$ (3.3)	$ (115.3)
Unrealized pension and postretirement benefit obligations	47.8	6.2	(9.5)
Reclassifications to net loss	(2.3)	(0.8)	1
Unrealized gain on plan amendment (see Note 17)	0	35.6	0
Unrealized net (loss) on derivatives (see Note 13)	(18.8)	0	0
Reclassifications to net earnings (loss) (see Note 13)	0.7	0	0
Unrealized foreign currency translation adjustments	(5.7)	5.5	(56.3)
Reclassifications to net loss (see Note 5)	0	(1.3)	0
Pension and postretirement benefits, tax	(8.3)	(16.5)	3.3
Hedging, tax	7	0	0
Total Comprehensive Income (Loss)	$ 68.7	$ 25.4	$ (176.8)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Current Assets
Cash and cash equivalents	$ 1,525.9	$ 1,143.6
Restricted cash	4.2	8.4
Receivables, net	480.6	385
Inventories	573.5	503.1
Prepaid expenses and other current assets	31.7	36.8
Total Current Assets	2,615.9	2,076.9
Property, net	1,690.7	1,354.4
Goodwill	4,032	3,079.7
Other intangible assets, net	3,353.9	2,833.7
Other assets	184.3	15.9
Total Assets	11,876.8	9,360.6
Current Liabilities
Current portion of long-term debt	22.1	12.3
Accounts payable	336	264.4
Other current liabilities	346.3	357.3
Total Current Liabilities	704.4	634
Long-term debt	7,149.1	4,551.2
Deferred income taxes	905.8	726.5
Other liabilities	327.8	440.3
Total Liabilities	9,087.1	6,352
Commitments and Contingencies
Shareholders’ Equity
Preferred Stock, Value, Issued	0	0
Common stock, $0.01 par value, 300.0 shares authorized, 66.1 and 64.9 shares outstanding, respectively	0.7	0.7
Additional paid-in capital	3,566.5	3,546
Accumulated deficit	(376)	(424.3)
Accumulated other comprehensive loss	(40)	(60.4)
Treasury stock, at cost, 5.8 and 1.8 shares, respectively	371.2	53.4
Total Shareholders’ Equity Excluding Noncontrolling Interest	2,780	3,008.6
Noncontrolling interest	9.7	0
Total Shareholders’ Equity	2,789.7	3,008.6
Total Liabilities and Shareholders’ Equity	$ 11,876.8	$ 9,360.6

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheet (Parentheticals) - $ / shares shares in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Par value of preferred stock	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	50,000	50,000
Common Stock, Shares Authorized	300,000	300,000
Common Stock, Shares, Issued	66,100	64,900
Par value of common stock	$ 0.01	$ 0.01
Treasury Stock, Shares	5,800	1,800
Series B Preferred Stock
Par value of preferred stock	$ 0.01
Preferred Stock, Dividend Rate, Percentage	3.75%	3.75%
Preferred stock issued	1,500	1,500
Preferred Stock, Shares Outstanding	1,500	1,500
Series C Preferred Stock
Par value of preferred stock	$ 0.01
Preferred Stock, Dividend Rate, Percentage	2.50%	2.50%
Preferred stock issued	3,200	3,200
Preferred Stock, Shares Outstanding	3,200	3,200

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Cash Flows from Operating Activities:
Net earnings (loss)	$ 48.3	$ (3.3)	$ (115.3)
Adjustments to reconcile of net (loss) earnings to net cash provided by operating activities:
Depreciation and amortization	323.1	302.8	272.8
Loss on extinguishment of debt, net	222.9	86.4	30
(Gain) loss on foreign currency	(30.8)	(0.2)	4.3
Impairment of goodwill and other intangible assets	26.5	0	60.8
Unrealized (gain) loss on interest rate swaps and cross-currency swaps, net	(93.6)	182.4	92.5
Assets held for sale	(0.2)	9.3	34.2
Non-cash stock-based compensation expense	23.6	17.2	22.7
Deferred income taxes	17.4	(74.6)	(120.1)
Other, net	4.4	0.8	9.1
Other changes in current assets and liabilities, net
(Increase) decrease in receivables	(52.1)	(4)	89.5
(Increase) decrease in inventories	(2.5)	(37.2)	30.5
Decrease (increase) in prepaid expenses and other current assets	3.7	(3.5)	(7)
(Decrease) increase in accounts payable and other current liabilities	(109)	18.8	46
Increase in non-current liabilities	5	7.5	1.6
Net Cash Provided by Operating Activities	386.7	502.4	451.6
Cash Flows from Investing Activities
Business acquisitions, net of cash acquired	(1,915.2)	(94.4)	(1,239.2)
Additions to property	(190.4)	(121.5)	(107.9)
Restricted cash	4.2	10.4	72.1
Proceeds from sale of property and assets held for sale	10.6	2.1	20.4
Proceeds from sale of businesses	0	7.3	3.8
Insurance proceeds on property losses	0	0	2.1
Net Cash Used in Investing Activities	(2,090.8)	(196.1)	(1,248.7)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt	4,700	1,750	1,896.5
Proceeds from issuance of common stock, net of issuance costs	0	0	732.7
Repayments of long-term debt	(2,088.4)	(1,632.2)	(1,225.1)
Purchases of treasury stock	(317.8)	0	0
Payments of preferred stock dividends	(13.5)	(14.4)	(17.1)
Premium from issuance of long-term debt	41.2	0	0
Preferred stock conversion	0	(10.9)	0
Payments of debt issuance costs	(59)	(24.3)	(31.5)
Payment of premium on debt extinguishment	(219.8)	(88)	0
Proceeds from exercise of stock awards	13.4	6.6	15.5
Net cash received from stock repurchase contracts	0	1.1	0
Other, net	(3)	7.6	1.4
Net Cash Provided by (Used in) Financing Activities	2,053.1	(4.5)	1,372.4
Effect of Exchange Rate Changes on Cash and Cash Equivalents	33.3	0.4	(2.3)
Net Increase in Cash and Cash Equivalents	382.3	302.2	573
Cash and Cash Equivalents, Beginning of Year	1,143.6	841.4	268.4
Cash and Cash Equivalents, End of Year	$ 1,525.9	$ 1,143.6	$ 841.4

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Retirement Benefit Adjustments, net of tax	Hedging Adjustments, net of tax	Foreign Currency Translation Adjustments	Treasury Stock	Non-Controlling Interest
Balance at beginning of period at Sep. 30, 2014	$ 2,283.2	$ 0.1	$ 0.5	$ 2,669.3	$ (305.7)	$ (21.4)		$ (6.2)	$ (53.4)
Preferred Stock, Beginning Balance (shares) at Sep. 30, 2014		5.6
Common Stock, Beginning Balance (shares) at Sep. 30, 2014			44.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(115.3)				(115.3)
Preferred stock dividends declared	(17.1)			(17.1)
Issuance of common stock	847.1		$ 0.1	847
Issuance of common stock (shares)			16.7
Activity under stock and deferred compensation plans	$ 16.9			16.9
Activity under stock and deferred compensation plans (shares)	0.6
Stock-based compensation expense	$ 22.7			22.7
Net cash received from stock repurchase contracts	0
Other comprehensive income (loss):
Net change in retirement benefits, net of tax	(5.2)					(5.2)
Foreign currency translation adjustments	(56.3)							(56.3)
Balance at the end of period at Sep. 30, 2015	2,976	$ 0.1	$ 0.6	3,538.8	(421)	(26.6)		(62.5)	(53.4)
Preferred Stock, Ending Balance (shares) at Sep. 30, 2015		5.6
Common Stock, Ending Balance (shares) at Sep. 30, 2015			62.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	(3.3)				(3.3)
Preferred stock dividends declared	(14.4)			(14.4)
Preferred stock conversion (see Note 20)	(10.9)	$ (0.1)	$ 0.1	(10.9)
Preferred stock conversion (see Note 20) (shares)			2
Activity under stock and deferred compensation plans	14.2			14.2
Activity under stock and deferred compensation plans (shares)			0.6
Stock-based compensation expense	17.2			17.2
Net cash received from stock repurchase contracts	1.1			1.1
Tangible equity units conversion (shares)			0.2
Other comprehensive income (loss):
Net change in retirement benefits, net of tax	24.5					24.5
Foreign currency translation adjustments	4.2							4.2
Balance at the end of period at Sep. 30, 2016	3,008.6	$ 0	$ 0.7	3,546	(424.3)	(2.1)		(58.3)	(53.4)
Preferred Stock, Ending Balance (shares) at Sep. 30, 2016		4.7
Common Stock, Ending Balance (shares) at Sep. 30, 2016			64.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss)	48.3				48.3
Preferred stock dividends declared	(13.5)			(13.5)
Activity under stock and deferred compensation plans	10.4			10.4
Activity under stock and deferred compensation plans (shares)			0.5
Stock-based compensation expense	23.6			23.6
Purchases of treasury stock	(317.8)		$ 317.8						(317.8)
Purchases of treasury stock (shares)			(4)
Net cash received from stock repurchase contracts	0
Non-controlling interest in acquisition	9.7									$ 9.7
Tangible equity units conversion (shares)			4.7
Other comprehensive income (loss):
Net change in retirement benefits, net of tax	37.2					37.2
Net change in hedges, net of tax	(11.1)						$ (11.1)
Foreign currency translation adjustments	(5.7)							(5.7)
Balance at the end of period at Sep. 30, 2017	$ 2,789.7	$ 0	$ 0.7	$ 3,566.5	$ (376)	$ 35.1	$ (11.1)	$ (64)	$ (371.2)	$ 9.7
Preferred Stock, Ending Balance (shares) at Sep. 30, 2017		4.7
Common Stock, Ending Balance (shares) at Sep. 30, 2017			66.1

Background

Background	12 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background	BACKGROUND Post Holdings, Inc. (“Post” or the “Company”) is a consumer packaged goods holding company operating in the center-of-the-store, foodservice, food ingredient, refrigerated, active nutrition and private brand food categories. The Company’s products are sold through a variety of channels such as grocery, club and drug stores, mass merchandisers, foodservice, ingredient and via the internet. Post operates in five reportable segments: Post Consumer Brands, Michael Foods Group, Active Nutrition, Private Brands and Weetabix. The Post Consumer Brands segment includes the North American ready-to-eat (“RTE”) cereal and granola businesses, inclusive of the recently acquired Weetabix North American RTE cereal business, the Michael Foods Group segment includes predominantly foodservice and food ingredient egg, potato and pasta businesses and a retail cheese business, the Active Nutrition segment includes protein shakes, bars and powders and nutritional supplements, the Private Brands segment primarily consists of peanut and other nut butters and dried fruit and nuts and the Weetabix segment includes the international (primarily United Kingdom) RTE cereal and muesli business. On February 6, 2012, Post common stock began trading on the New York Stock Exchange under the ticker symbol “POST.” Unless otherwise stated or the context otherwise indicates, all references in this Form 10-K to “Post,” “the Company,” “us,” “our” or “we” mean Post Holdings, Inc. and its consolidated and non-consolidated subsidiaries. Certain prior year amounts have been reclassified to conform with the 2017 presentation. These reclassifications had no impact on Net Loss or Shareholders’ Equity, as previously reported.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Signifcant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation — The consolidated financial statements include the operations of Post and its wholly-owned and majority-owned subsidiaries. All intercompany transactions have been eliminated. Use of Estimates and Allocations — The consolidated financial statements of the Company are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), which require certain elections as to accounting policy, estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent liabilities at the dates of the financial statements and the reported amount of net revenues and expenses during the reporting periods. Significant accounting policy elections, estimates and assumptions include, among others, pension and benefit plan assumptions, valuation assumptions of goodwill and other intangible assets, marketing programs, self insurance reserves and income taxes. Actual results could differ from those estimates. Business Combinations — The Company uses the acquisition method in accounting for acquired businesses. Under the acquisition method, our financial statements reflect the operations of an acquired business starting from the completion of the acquisition. The assets acquired and liabilities assumed are recorded at their respective estimated fair values at the date of the acquisition. Any excess of the purchase price over the estimated fair values of the identifiable net assets acquired is recorded as goodwill. Cash Equivalents — Cash equivalents include all highly liquid investments with original maturities of less than three months. Restricted Cash — Restricted cash includes items such as cash deposits which serve as collateral for certain commodity hedging contracts as well as the Company's high deductible workers’ compensation insurance program. In addition, restricted cash at September 30, 2016 included deposits with third party escrow agents in connection with an acquisition that was credited against the purchase price when the transaction closed. Receivables — Receivables are reported at net realizable value. This value includes appropriate allowances for doubtful accounts, cash discounts, and other amounts which the Company does not ultimately expect to collect. The Company determines its allowance for doubtful accounts based on historical losses as well as the economic status of, and its relationship with its customers, especially those identified as “at risk.” A receivable is considered past due if payments have not been received within the agreed upon invoice terms. Receivables are written off against the allowance when the customer files for bankruptcy protection or are otherwise deemed to be uncollectible based upon the Company’s evaluation of the customer’s solvency. The Weetabix Group, acquired July 3, 2017 (as defined and described in Note 5), sells certain receivables to third party institutions without recourse. The amount sold from the date of acquisition through September 30, 2017 was $37.3 . Inventories — Inventories, other than flocks, are generally valued at the lower of average cost (determined on a first-in, first-out basis) or net realizable value. Reported amounts have been reduced by an allowance for obsolete product and packaging materials based on a review of inventories on hand compared to estimated future usage and sales. Flock inventory represents the cost of purchasing and raising chicken flocks to egg laying maturity. The costs included in our flock inventory include the costs of the chicks, the feed fed to the birds and the labor and overhead costs incurred to operate the pullet facilities until the birds are transferred into the laying facilities, at which time their cost is amortized to operations, as cost of goods sold, over their expected useful lives of one to two years. Restructuring Expenses and Assets Held for Sale — Restructuring charges principally consist of severance, accelerated stock compensation and other employee separation costs, accelerated depreciation and certain long-lived asset impairments. The Company recognizes restructuring obligations and liabilities for exit and disposal activities at fair value in the period the liability is incurred. Employee severance costs are expensed when they become probable and reasonably estimable under established severance plans. Depreciation expense related to assets that will be disposed of or idled as a part of the restructuring activity is accelerated through the expected date of the asset shut down. Assets are classified as held for sale if the Company has committed to a plan for selling the assets, is actively and reasonably marketing them, and sale is reasonably expected within one year. The carrying value of assets held for sale is included in “Prepaid expenses and other current assets” on the Consolidated Balance Sheets. See Note 4 for information about restructuring expenses and assets held for sale. 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 20 years for machinery and equipment; 1 to 40 years for buildings, building improvements and leasehold improvements; and 1 to 5 years for software. Total depreciation expense was $164.0 , $150.2 and $131.1 in fiscal 2017 , 2016 and 2015 , respectively. Any gains and losses incurred on the sale or disposal of assets are included in "Other operating expenses, net” in the Consolidated Statements of Operations. Repair and maintenance costs incurred in connection with on-going and planned major maintenance activities are accounted for under the direct expensing method. Property consisted of: September 30, 2017 2016 Land and land improvements $ 90.9 $ 58.0 Buildings and leasehold improvements 699.4 618.2 Machinery and equipment 1,439.3 1,094.5 Software 64.5 50.4 Construction in progress 100.0 79.2 2,394.1 1,900.3 Accumulated depreciation (703.4 ) (545.9 ) $ 1,690.7 $ 1,354.4 Other Intangible Assets — Other intangible assets consist primarily of customer relationships and trademarks/brands acquired in business combinations and includes 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 $159.1 , $152.6 , and $141.7 in fiscal 2017 , 2016 and 2015 , respectively. For the definite-lived intangible assets recorded as of September 30, 2017 , amortization expense of $167.5 , $166.6 , $166.5 , $166.5 and $163.8 is expected for fiscal 2018 , 2019 , 2020 , 2021 and 2022 , respectively. Other intangible assets consisted of: September 30, 2017 September 30, 2016 Carrying Amount Accum. Amort. Net Amount Carrying Amount Accum. Amort. Net Amount Subject to amortization: Customer relationships $ 2,249.3 $ (416.7 ) $ 1,832.6 $ 2,012.7 $ (302.0 ) $ 1,710.7 Trademarks/brands 834.1 (162.9 ) 671.2 795.1 (120.6 ) 674.5 Other 21.7 (9.8 ) 11.9 21.7 (7.7 ) 14.0 3,105.1 (589.4 ) 2,515.7 2,829.5 (430.3 ) 2,399.2 Not subject to amortization: Trademarks/brands 838.2 — 838.2 434.5 — 434.5 $ 3,943.3 $ (589.4 ) $ 3,353.9 $ 3,264.0 $ (430.3 ) $ 2,833.7 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 goodwill. Trademarks with indefinite lives are reviewed for impairment during the fourth quarter of each fiscal year following the annual forecasting process, or more frequently if facts and circumstances indicate the trademark may be impaired. The trademark impairment tests require us to estimate the fair value of the trademark and compare it to its carrying value. The estimated fair value is determined using an income-based approach (the relief-from-royalty method), which requires significant assumptions for each brand, including estimates regarding future revenue growth, discount rates, and appropriate royalty rates. Assumptions are determined after consideration of several factors for each brand, including profit levels, research of external royalty rates by third party experts and the relative importance of each brand to the Company. Revenue growth assumptions are based on historical trends and management’s expectations for future growth by brand. The discount rate is based on a weighted-average cost of capital utilizing industry market data of similar companies. In addition, definite-lived assets and indefinite-lived intangible assets are reassessed as needed when information becomes available that is believed to negatively impact the fair market value of an asset. In general, an asset is deemed impaired and written down to its fair value if estimated related future cash flows are less than its carrying amount. See Note 6 for information about goodwill impairments. For the year ended September 30, 2017, the Company conducted an impairment review and concluded there was no impairment of other intangible assets as of September 30, 2017. At September 30, 2017, the fair value of the Honey Bunches of Oats brand exceeded its carrying value of $243.9 by 8% . For the year ended September 30, 2016, the Company conducted an impairment review and concluded there was no impairment of other intangible assets as of September 30, 2016. At September 30, 2016, the estimated fair values of all other intangible assets exceeded their carrying value by at least 36% . At September 30, 2015, Post recorded impairment losses in the Post Consumer Brands segment of $3.7 for the Grape-Nuts brand and $0.1 for the 100% Bran brand to record these trademarks at their estimated current fair values of $11.2 and zero , respectively. Due to repeated past impairments, continued weakness in the brand forecasts and a lack of sales growth from recent brand support efforts, as of October, 1 2015, the Grape-Nuts brand was converted to a definite-lived asset and assigned a 20 year useful life. These fair value measurements fell within Level 3 of the fair value hierarchy as described in Note 14. The trademark impairment losses are reported in “Impairment of goodwill and other intangible assets” on the Consolidated Statements of Operations. Deferred Compensation Investments — The Company funds a portion of its deferred compensation liability by investing in certain mutual funds in the same amounts as selected by the participating employees. Because management’s intent is to invest in a manner that matches the deferral options chosen by the participants and those participants can elect to transfer amounts in or out of each of the designated deferral options at any time, these investments have been classified as trading assets and are stated at fair value in “Prepaid expenses and other current assets” and “Other Assets” (see Note 14). Both realized and unrealized gains and losses on these assets are included in “Selling, general and administrative expenses” and offset the related change in the deferred compensation liability. Revenue — Revenue is recognized when title of goods and risk of loss is transferred to the customer, as specified by the shipping terms. Net sales reflect gross sales, including amounts billed to customers for shipping and handling, less sales discounts and trade allowances (including promotional price buy downs and new item promotional funding). Customer trade allowances are generally computed as a percentage of gross sales. Products are generally sold with no right of return except in the case of goods which do not meet product specifications or are damaged, and related reserves are maintained based on return history. If additional rights of return are granted, revenue recognition is deferred. Estimated reductions to revenue for customer incentive offerings are based upon customer redemption history. Cost of Goods Sold — Cost of goods sold includes, among other things, inbound and outbound freight costs 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 Statement of Operations. Storage and other warehousing costs totaled $ 142.9 , $ 124.1 and $ 103.4 in fiscal 2017 , 2016 and 2015 , respectively. Advertising — Advertising costs are expensed as incurred except for costs of producing media advertising such as television commercials or magazine advertisements, which are deferred until the first time the advertising takes place. The amounts reported as assets on the balance sheet as “Prepaid expenses and other current assets” were $1.3 and $1.6 as of September 30, 2017 and 2016 , respectively. Stock-based Compensation — The Company recognizes the cost of employee services received in exchange for awards of equity instruments based on the grant-date fair value of equity awards and the fair market value at each quarterly reporting date for liability awards. That cost is recognized over the period during which an employee is required to provide service in exchange for the award — the requisite service period (usually the vesting period). See Note 18 for disclosures related to stock-based compensation. Income Tax Expense (Benefit) — Income tax expense (benefit) is estimated based on income taxes in each jurisdiction and includes the effects of both current tax exposures and the temporary differences resulting from differing treatment of items for tax and financial reporting purposes. These temporary differences result in deferred tax assets and liabilities. A valuation allowance is established against the related deferred tax assets to the extent that it is not more likely than not that the future benefits will 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 due to an underpayment of income taxes is classified as income taxes. The Company considers the undistributed earnings of its foreign subsidiaries to be permanently reinvested, so no U.S. taxes have been provided in relation to the Company's investment in its foreign subsidiaries. See Note 8 for disclosures related to income taxes.

Recently Issued and Adopted Acc

Recently Issued and Adopted Accounting Standards	12 Months Ended
	Sep. 30, 2017
Recently Issued Accounting Standards [Abstract]
Recently Issued and Adopted Accounting Standards	RECENTLY ISSUED AND ADOPTED ACCOUNTING STANDARDS The Company has considered all new accounting pronouncements, and has concluded there are no new pronouncements (other than the ones described below) that had or will have an impact on the results of operations, other comprehensive income (“OCI”), financial condition, cash flows or shareholders’ equity based on current information. Recently Issued In March 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost.” ASU 2017-07 requires an entity to report the service cost component of periodic net benefit cost as an operating expense in the same line item or items as other compensation costs arising from services rendered by employees during the period. Other components of net benefit cost are to be presented outside of income from operations in the income statement separately from the service cost component. The amendments in this ASU also allow only the service cost component to be eligible for capitalization when applicable. This ASU is effective for annual periods beginning after December 15, 2017 and interim periods therein (i.e., Post’s financial statements for the year ending September 30, 2019), with early adoption permitted. Additionally, this ASU requires a retrospective method of adoption. The adoption of this ASU will result in a change in operating profit and a corresponding change to other (income) expense, net to reflect the exclusion of all components of net benefit cost, with the exception of service cost, from operating profit. For the year ended September 30, 2017, the reclassification would have resulted in a decrease in operating profit of $3.6. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842).” This standards update requires a company to recognize right-of-use assets and lease liabilities on its balance sheet and disclose key information about leasing arrangements. ASU 2016-02 offers specific accounting guidance for lessees, lessors and sale and leaseback transactions. Lessees and lessors are required to disclose qualitative and quantitative information about leasing arrangements to enable a user of the financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. This ASU is effective for annual periods beginning after December 15, 2018 and interim periods therein (i.e., Post’s financial statements for the year ending September 30, 2020), with early adoption permitted. At adoption, this update will be applied using a modified retrospective approach. The Company is currently evaluating the impact and timing of adopting this guidance, however, an increase in both assets and liabilities is expected. In January 2017, the FASB issued ASU 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” ASU 2017-01 adds guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses by providing a more specific definition of a business. This ASU is effective for annual periods beginning after December 15, 2017 and interim periods therein (i.e., Post’s financial statements for the year ending September 30, 2019), with early adoption permitted. This ASU currently has no impact on the Company, however, Post will evaluate the impact of this ASU on future business acquisitions and disposals. In December 2016, the FASB issued ASU 2016-20, “Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers.” ASU 2016-20 is intended to clarify and suggest improvements to the application of current standards under Topic 606 and other Topics amended by ASU 2014-09, “Revenue from Contracts with Customers (Topic 606).” The effective date of this ASU is the same as the effective date for ASU 2014-09 (i.e., Post’s financial statements for the year ending September 30, 2019). The Company is assessing the impact that the standard will have on its accounting policies, processes, system requirements, internal controls and disclosures. Internal resources have been assigned to this assessment, and the Company has engaged a third party to assist in the assessment and implementation. The Company has established a project plan, identified key revenue streams, completed an initial review of its customer contracts and is considering impacted policies and processes. The Company will adopt the standard on October 1, 2018 and expects to use the modified retrospective transition method of adoption. The Company continues to evaluate the effect that ASU 2014-09 will have on the consolidated financial statements and related disclosures. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash.” ASU 2016-18 requires that a statement of cash flows explain the change in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents, and therefore, restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning of year cash balance to the end of year cash balance as shown on the statement of cash flows. This ASU is effective for annual periods beginning after December 15, 2017 and interim periods therein (i.e., Post’s financial statements for the year ending September 30, 2019), with early adoption permitted. The Company currently classifies changes in restricted cash as an investing activity in the Condensed Consolidated Statements of Cash Flows, not as a component of cash and cash equivalents as required by this ASU. Based on the historical balances of restricted cash on the Consolidated Balance Sheets, the change is not expected to be material. The Company is currently evaluating the timing of adopting this ASU. Recently Adopted In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging (Topic 715): Targeted Improvements to Accounting for Hedging Activities.” ASU 2017-12 amends and simplifies existing guidance in order to allow companies to more accurately present the economic effects of risk management activities in the financial statements. This ASU requires a cumulative-effect adjustment related to eliminating the separate measurement of ineffectiveness to accumulated OCI with a corresponding adjustment to the opening balance of retained earnings as of the beginning of the fiscal year that a company adopts the ASU. In addition, this ASU requires amended presentation and disclosure guidance to be applied prospectively. The Company early adopted this ASU in fiscal 2017, as permitted by the standard. The adoption of this guidance modified the presentation of disclosures in Note 13, but did not have an impact on the Company’s financial statements. In January 2017, the FASB issued ASU 2017-04, “Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” ASU 2017-04 eliminates step two of the goodwill impairment test, which requires the calculation of the implied fair value of goodwill to measure a goodwill impairment charge. Under this ASU, an entity should perform its annual or interim goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount, and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value with the loss not exceeding the total amount of goodwill allocated to that reporting unit. The Company early adopted this ASU using a prospective approach during the fourth quarter of fiscal 2017, as permitted by the standard. The adoption of this ASU resulted in an impairment of goodwill of $26.5 in the Active Nutrition segment in the year ended September 30, 2017. See Note 6 for further discussion of this impairment. In March 2016, the FASB issued ASU 2016-09, “Compensation - Stock Compensation (Topic 718): Improvement to Employee Share-Based Payment Accounting.” The updated guidance changes the accounting for certain aspects of share-based payment awards to employees, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification of certain items in the statement of cash flows. The Company early adopted this ASU during fiscal 2017, as permitted by the standard. The adoption of this ASU did not have a material impact on the Company’s Consolidated Financial Statements and included the following items: (i) adoption on a prospective basis of the recognition of excess tax benefits and tax deficiencies in income tax expense (benefit) in the Consolidated Statement of Operations for vested and exercised equity awards as discrete items in the period in which they occur; (ii) adoption on a modified retrospective basis of recording forfeitures for share based awards as they occur rather than estimating future forfeitures and their effect on expense; (iii) adoption on a prospective basis of the classification of excess tax benefits in cash flows from operations in the Company’s Consolidated Statements of Cash Flows resulting in reclassifications of $6.2 of excess tax benefits from the exercise of stock awards in the Consolidated Statements of Cash Flows from “Other, net” within financing activities to “Other, net” within operating activities for the year ended September 30, 2017 ( $9.6 and $3.3 for the years ended September 30, 2016 and 2015, respectively, had the standard been adopted retrospectively), as well as from “Additional paid-in capital” on the Consolidated Balance Sheets to “Income tax expense (benefit)” on the Consolidated Statements of Operations; and (iv) adoption on a prospective basis for the exclusion of the amount of excess tax benefits when applying the treasury stock method for the Company’s diluted earnings per share calculation.

Restructuring Restructuring

Restructuring Restructuring	12 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Restructuring	RESTRUCTURING In September 2015, the Company announced its plan to close its Dymatize manufacturing facility located in Farmers Branch, Texas and permanently transfer production to third party facilities under co-manufacturing agreements. Plant production ceased in the fourth quarter of 2015, and the facility was sold in December 2016. No additional restructuring costs were incurred in fiscal 2017. In May 2015, the Company announced its plan to consolidate its cereal business administrative offices into its Lakeville, Minnesota location. In connection with the consolidation, the Company closed its office located in Parsippany, New Jersey and relocated those functions as well as certain functions located in Battle Creek, Michigan to the Lakeville office. The Parsippany office closure was completed during fiscal 2016. No additional restructuring costs were incurred in fiscal 2017. In March 2015, the Company announced its plan to close its facility in Boise, Idaho, which manufactured certain PowerBar products distributed in North America. Plant production ceased in June 2015 and the facility was sold in September 2015. No additional restructuring costs were incurred in fiscal 2017 or 2016. In April 2013, the Company announced management’s decision to close its cereal plant located in Modesto, California as part of a cost savings and capacity rationalization effort. The transfer of production capabilities and closure of the plant was completed during September 2014, the facility was sold in March 2017 and no additional restructuring costs were incurred in fiscal 2017, 2016 or 2015. Amounts related to the restructuring events are shown in the following table. Costs are recognized in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. These expenses are not included in the measure of segment performance for any segment (see Note 21). Employee-Related Costs Pension Curtailment Accelerated Depreciation Total Balance, September 30, 2014 $ 0.7 $ — $ — $ 0.7 Charge to expense 13.2 — 2.1 15.3 Cash payments (3.4 ) — — (3.4 ) Non-cash charges — — (2.1 ) (2.1 ) Balance, September 30, 2015 $ 10.5 $ — $ — $ 10.5 Charge to expense 2.1 — 0.4 2.5 Cash payments (10.6 ) — — (10.6 ) Non-cash charges (0.9 ) — (0.4 ) (1.3 ) Balance, September 30, 2016 $ 1.1 $ — $ — $ 1.1 Charge to expense — — — — Cash payments (1.1 ) — — (1.1 ) Non-cash charges — — — — Balance, September 30, 2017 $ — $ — $ — $ — Total expected restructuring charge $ 18.5 $ 1.7 $ 20.1 $ 40.3 Cumulative incurred to date 18.5 1.7 20.1 40.3 Remaining expected restructuring charge $ — $ — $ — $ — Assets Held for Sale Related to the closure of its Modesto, California facility in September 2014, the Company had land, building and equipment classified as assets held for sale at September 30, 2016. The carrying value of the assets included in “Prepaid expenses and other current assets” in the Consolidated Balance Sheets was $4.3 as of September 30, 2016. The land, building and equipment were sold in March 2017. Related to the manufacturing shutdown of its Farmers Branch, Texas facility in September 2015, the Company had land and buildings classified as assets held for sale at September 30, 2016. The carrying value of the assets included in “Prepaid expenses and other current assets” on the Consolidated Balance Sheets was $5.8 as of September 30, 2016. The land and buildings were sold in December 2016. There were no assets held for sale at September 30, 2017. Held for sale net (gains) and losses of $(0.2) , $9.3 and $34.2 were recorded in fiscal 2017 , 2016 and 2015 , respectively, to adjust the carrying value of the assets to their fair value less estimated selling costs. The net gains recorded in fiscal 2017 related to the Farmers Branch, Texas facility. The losses recorded in fiscal 2016 included amounts related to the Modesto, California and Farmers Branch, Texas facilities. The losses recorded in fiscal 2015 included amounts related to the closure of the Modesto, California and Farmers Branch, Texas facilities, as well as the sale of a Boise, Idaho manufacturing facility, the sale of a peanut butter manufacturing facility located in Portales, New Mexico and the sale of the Australian business and Musashi trademark. The net gains and losses are reported as “Other operating expenses, net” on the Consolidated Statements of Operations.

Business Combinations and Dives

Business Combinations and Divestitures Business Combinations	12 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Business Combinations and Divestitures	BUSINESS COMBINATIONS AND DIVESTITURES The Company accounts for acquisitions using the acquisition method of accounting, whereby the results of operations are included in the financial statements from the date of acquisition. The purchase price is allocated to acquired assets and assumed liabilities based on their estimated fair values at the date of acquisition, and any excess is allocated to goodwill. Goodwill represents the value the Company expects to achieve through the implementation of operational synergies and the expansion of the business into new or growing segments of the industry. Fiscal 2017 Acquisitions On July 3, 2017, the Company completed its acquisition of Latimer Newco 2 Limited, a company registered in England and Wales (“Latimer”), and all of Latimer’s direct and indirect subsidiaries at the time of acquisition, including Weetabix Limited (collectively the “Weetabix Group”) for a purchase price of approximately £1,400.0 with a payment at closing of £1,454.1 , excluding £48.0 of cash acquired (approximately $1,887.2 , excluding $62.2 of cash acquired). The Weetabix Group is a packaged food company that primarily produces branded and private label RTE cereal and muesli products. The Weetabix Group is reported in two reportable segments. The results of the Weetabix operations outside of North America (“Weetabix”) are reported in the Weetabix segment, and the Weetabix North American operations (“Weetabix NA”) are reported in the Post Consumer Brands segment (see Note 21). Based on the preliminary purchase price allocation of Weetabix, the Company recorded $172.8 of customer relationships to be amortized over a weighted-average period of approximately 20 years, $30.5 to definite-lived trademarks and brands to be amortized over a weighted-average period of 16 years and $391.0 of indefinite-lived trademarks. Based on the preliminary purchase price allocation of Weetabix NA, the Company recorded $14.1 of customer relationships to be amortized over a weighted-average period of 21 years. Net sales and operating profit for Weetabix included in the Consolidated Statements of Operations were $112.4 and $14.5 , respectively, for the year ended September 30, 2017 . Net sales and operating loss for Weetabix NA included in the Consolidated Statements of Operations were $28.1 and $6.4 , respectively, for the year ended September 30, 2017 . On October 3, 2016, the Company completed its acquisition of National Pasteurized Eggs, Inc. (“NPE”) for $93.5 , subject to working capital and other adjustments, resulting in a payment at closing of $97.0 . In February 2017, a final settlement of net working capital and other adjustments was reached, resulting in an amount back to the Company of $1.2 . In addition, the Company acquired an income tax receivable of $0.7 that is due back to the sellers. NPE is a producer of pasteurized shell eggs, including cage-free eggs, and is reported in the Michael Foods Group segment (see Note 21). Based upon the purchase price allocation, the Company recorded $43.9 of customer relationships to be amortized over a weighted-average period of 16 years and $7.5 of trademarks and brands to be amortized over a weighted-average period of 20 years. NPE operations have been integrated into the Michael Foods business, and due to the level of integration, discrete sales and operating profit data for the year ended September 30, 2017 is not available for NPE. The following table provides the allocation of the purchase price related to the fiscal 2017 acquisitions of NPE and the preliminary purchase price related to the acquisition of the Weetabix Group based upon the fair value of assets and liabilities assumed. Certain preliminary values of the Weetabix Group acquisition, including receivables, inventory, property, goodwill, other intangible assets, other assets, other current liabilities, deferred taxes and other liabilities, are not yet finalized pending the final purchase price allocation and are subject to change once additional information is obtained. Measurement period adjustments have been made to the allocation of purchase price for the acquisition of NPE since the date of acquisition related to working capital settlements, updated valuations of property and intangibles, income tax receivable and deferred taxes. The fair value of goodwill related to the acquisition of NPE will not be deductible for U.S. income tax purposes. The Company does not expect the final fair value of goodwill related to the acquisition of the Weetabix Group to be deductible for U.S. income tax purposes. NPE The Weetabix Group Cash and cash equivalents $ 5.6 $ 62.2 Receivables 8.5 39.7 Inventories 2.1 63.4 Prepaid expenses and other current assets 0.4 1.2 Property 10.4 283.9 Goodwill 46.3 969.3 Other intangible assets 51.4 608.4 Other assets — 112.0 Current portion of capital lease (0.1 ) — Accounts payable (6.3 ) (66.3 ) Other current liabilities (2.9 ) (28.4 ) Long-term capital lease (0.2 ) — Deferred tax liability - long-term (18.7 ) (137.6 ) Other liabilities — (10.9 ) Noncontrolling interest — (9.7 ) Total acquisition cost $ 96.5 $ 1,887.2 Fiscal 2016 Acquisitions On October 3, 2015, the Company completed its acquisition of Willamette Egg Farms (“WEF”) for $90.0 , subject to working capital and other adjustments, resulting in a payment at closing of $109.0 . In December 2015, a final settlement of net working capital and other adjustments was reached, resulting in an additional amount paid by the Company of $4.6 . WEF is a producer, processor and wholesale distributor of eggs and egg products and is reported in the Michael Foods Group segment (see Note 21). Based upon the purchase price allocation, the Company recorded $12.7 of customer relationships to be amortized over a weighted-average period of 20 years and $2.5 to trademarks and brands to be amortized over a weighted-average period of 20 years. The following table provides the allocation of the purchase price related to the fiscal 2016 acquisition of WEF based upon the fair value of assets and liabilities assumed. The Company expects the final fair value of goodwill related to the acquisition of WEF to be deductible for U.S. income tax purposes. WEF Cash and cash equivalents $ 19.2 Receivables 11.1 Inventories 10.3 Prepaid expenses and other current assets 0.5 Property 56.2 Goodwill 4.2 Other intangible assets 15.2 Other assets 0.1 Accounts payable (2.2 ) Other current liabilities (1.0 ) Total acquisition cost $ 113.6 Divestitures In March 2016, the Company sold certain assets of its Michael Foods Canadian egg business, included in the Michael Foods Group segment (see Note 21), to a third party for $6.9 , subject to working capital and other adjustments, resulting in net cash received of $6.4 . In May 2016, a final settlement of net working capital and other adjustments was reached, resulting in additional cash received by the Company of $0.5 . During the year ended September 30, 2016, the Company recorded a gain of $2.0 related to the transaction, which includes $1.3 of foreign exchange gains that were previously included in accumulated OCI. This gain is reported as “Other operating expenses, net” in the Consolidated Statements of Operations. Fiscal 2015 Acquisitions On October 1, 2014, the Company completed its acquisition of the PowerBar and Musashi brands and related worldwide assets from Nestlé S.A. (“PowerBar”) for $150.0 , subject to a working capital adjustment, which resulted in a payment at closing of $136.1 . In March 2015, a final settlement of net working capital and other adjustments was reached, resulting in an amount back to the Company of approximately $1.7 . Based upon the purchase price allocation, the Company recorded $21.0 of customer relationships to be amortized over a weighted-average period of 18.3 years and $40.0 to trademarks and brands to be amortized over a weighted-average period of 20 years. PowerBar is reported in the Active Nutrition segment (see Note 21). On November 1, 2014, the Company completed its acquisition of American Blanching Company (“ABC”) for $128.0 . ABC is a manufacturer of peanut butter for national brands, private label retail and industrial markets and provider of peanut blanching, granulation and roasting services for the commercial peanut industry. Based upon the purchase price allocation, the Company recorded $63.9 of customer relationships to be amortized over a weighted-average period of 17 years and $8.0 to trademarks and brands to be amortized over a weighted-average period of 10 years. ABC is reported in the Private Brands segment (see Note 21). On May 4, 2015, Post completed its acquisition of MOM Brands Company (“MOM Brands”), a manufacturer and distributer of RTE cereals. MOM Brands is reported in the Post Consumer Brands segment (see Note 21). The closing purchase price of the transaction was $1,181.5 and was partially paid by the issuance of 2.45 million shares of the Company’s common stock to the former owners of MOM Brands. The shares were valued at the May 1, 2015 closing price of $46.60 per share for a total issuance of $114.4 . In September 2015, a final settlement of net working capital and other adjustments was reached, resulting in an amount back to the Company of $4.0 . Based upon the purchase price allocation, the Company recorded $185.6 of customer relationships to be amortized over a weighted-average period of 20 years and $178.8 to trademarks and brands to be amortized over a weighted-average period of 20 years. The following table provides the allocation of the purchase price based upon the fair value of assets and liabilities assumed for each acquisition completed in fiscal 2015. Substantially all of the final fair value of goodwill related to the acquisitions of PowerBar and MOM Brands will be deductible for U.S. income tax purposes and the final fair value of goodwill related to the acquisition of ABC will not be deductible for U.S. income tax purposes. PowerBar ABC MOM Brands Cash and cash equivalents $ 2.4 $ 0.6 $ 11.1 Receivables 6.5 12.8 41.7 Inventories 23.1 15.5 97.9 Prepaid expenses and other current assets 0.1 0.4 6.2 Property 17.9 19.7 532.1 Goodwill 18.6 49.6 195.6 Other intangible assets 61.0 71.9 364.4 Deferred tax asset - non-current 11.7 — — Other assets — 0.4 — Accounts payable (1.2 ) (9.0 ) (33.0 ) Deferred tax liability - current (0.2 ) (0.4 ) (5.4 ) Other current liabilities (4.4 ) (2.8 ) (24.9 ) Deferred tax liability - non-current (1.1 ) (30.7 ) (6.9 ) Other liabilities — — (1.3 ) Total acquisition cost $ 134.4 $ 128.0 $ 1,177.5 Divestitures On July 1, 2015, the Company sold the PowerBar Australia assets and Musashi trademark for $3.8 . By September 30, 2016, final settlements of net working capital and other adjustments were reached related to this sale, resulting in an additional amount received by the Company of $0.4 . In fiscal 2015, the Company recorded held for sale losses of $3.7 related to these assets in order to adjust the carrying value of the assets to their fair value less estimated selling costs. Both amounts were reported as “Other operating expenses, net” on the Consolidated Statements of Operations. PowerBar Australia was included in the Active Nutrition segment (see Note 21). Transaction related costs During the years ended September 30, 2017 , 2016 and 2015 , the Company incurred acquisition related expenses of $30.5 , $8.5 and $14.1 , respectively, recorded as “Selling, general and administrative expenses.” These costs include amounts for transactions that were signed, spending for due diligence on potential acquisitions that were not signed or announced at the time of the Company’s annual reporting, and spending for divestiture transactions. In addition, during the year ended September 30, 2017, the Company recorded net foreign currency gains of $30.0 related to cash held in British pounds sterling (GBP) to fund the acquisition of the Weetabix Group, which were recorded in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. Pro Forma Information The following unaudited pro forma information presents a summary of the combined results of operations of the Company and the aggregate results of all businesses acquired in fiscal years 2017 , 2016 and 2015 for the periods presented as if the fiscal 2017 acquisitions had occurred on October 1, 2015, the fiscal 2016 acquisitions had occurred on October 1, 2014 and the fiscal 2015 acquisitions had occurred on October 1, 2013 along with certain pro forma adjustments. These pro forma adjustments give effect to the amortization of certain definite-lived intangible assets, adjusted depreciation based upon fair value of assets acquired, interest expense related to the financing of the business combinations, inventory revaluation adjustments on acquired businesses, transaction and extinguished debt costs and related income taxes. The following unaudited pro forma information has been prepared for comparative purposes only and is not necessarily indicative of the results of operations as they would have been had the acquisitions occurred on the assumed dates, nor is it necessarily an indication of future operating results. 2017 2016 2015 Pro forma net sales $ 5,614.9 $ 5,751.2 $ 5,236.6 Pro forma net earnings (loss) available to common shareholders $ 71.9 $ 2.0 $ (73.3 ) Pro forma basic earnings (loss) per share $ 1.06 $ 0.03 $ (1.29 ) Pro forma diluted earnings (loss) per share $ 1.03 $ 0.03 $ (1.29 )

Goodwill

Goodwill	12 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL The changes in the carrying amount of goodwill by segment are noted in the following table. Post Consumer Brands Michael Foods Group Active Nutrition Private Brands Weetabix Total Balance, September 30, 2015 Goodwill (gross) $ 2,069.0 $ 1,341.6 $ 180.7 $ 178.9 $ — $ 3,770.2 Accumulated impairment losses (609.1 ) — (88.3 ) — — (697.4 ) Goodwill (net) $ 1,459.9 $ 1,341.6 $ 92.4 $ 178.9 $ — $ 3,072.8 Goodwill acquired — 4.2 — — — 4.2 Currency translation adjustment 0.1 — — 2.6 — 2.7 Balance, September 30, 2016 Goodwill (gross) $ 2,069.1 $ 1,345.8 $ 180.7 $ 181.5 $ — $ 3,777.1 Accumulated impairment losses (609.1 ) — (88.3 ) — — (697.4 ) Goodwill (net) $ 1,460.0 $ 1,345.8 $ 92.4 $ 181.5 $ — $ 3,079.7 Goodwill acquired 5.3 46.3 — — 964.0 1,015.6 Impairment loss — — (26.5 ) — — (26.5 ) Currency translation adjustment 0.3 — — — (37.1 ) (36.8 ) Balance, September 30, 2017 Goodwill (gross) $ 2,074.7 $ 1,392.1 $ 180.7 $ 181.5 $ 926.9 $ 4,755.9 Accumulated impairment losses (609.1 ) — (114.8 ) — — (723.9 ) Goodwill (net) $ 1,465.6 $ 1,392.1 $ 65.9 $ 181.5 $ 926.9 $ 4,032.0 Goodwill represents the excess of the cost of acquired businesses over the fair market value of their identifiable net assets. The Company conducts a goodwill impairment qualitative assessment during the fourth quarter of each fiscal year following the annual forecasting process, or more frequently if facts and circumstances indicate that goodwill may be impaired. The goodwill impairment qualitative assessment requires an analysis to determine if it is more likely than not that the fair value of the business is less than its carrying amount. If adverse qualitative trends are identified that could negatively impact the fair value of the business, a quantitative goodwill impairment test is performed. In fiscal years 2017 , 2016 and 2015 , the Company elected not to perform a qualitative assessment and instead performed a quantitative impairment test for all reporting units. The estimated fair value is determined using a combined income and market approach with a greater weighting on the income approach. The income approach is based on discounted future cash flows and requires significant assumptions, including estimates regarding future revenue, profitability, and capital requirements. The market approach is based on a market multiple (revenue and EBITDA which stands for earnings before interest, income taxes, depreciation, and amortization) and requires an estimate of appropriate multiples based on market data. For the year ended September 30, 2017, the Company recorded a charge of $26.5 for the impairment of goodwill. The impairment charge related to the Dymatize reporting unit which is included in the Active Nutrition segment. In fiscal 2017, consistent with the prior year, the specialty sports nutrition channel, in which Dymatize sells the majority of its products, continued to experience weak sales which resulted in management lowering its long-term expectations for the Dymatize reporting unit. After conducting step one of the impairment analysis, it was determined that the carrying value of the Dymatize reporting unit exceeded its fair value by $76.6 . As the application of ASU 2017-04 does not allow for step two of the analysis prescribed prior to the adoption of ASU 2017-04, the Company recorded an impairment charge for of goodwill down to the fair value. At the time of the analysis, the Dymatize reporting unit had $26.5 of remaining goodwill, and we therefore recorded an impairment charge for the entire goodwill balance of $26.5 . At September 30, 2017, the estimated fair values of all other reporting units exceeded their carrying values by at least 25% , with the exception of Weetabix, whose fair value only slightly exceeded its carrying value due to the recency of the acquisition. For the year ended September 30, 2016, the Company concluded there was no impairment of goodwill. With the exception of Dymatize, all reporting units passed step one of the impairment test. Dymatize failed step one and accordingly, step two of the analysis was performed. Based on the results of step two, it was determined that the fair value of the goodwill allocated to the Dymatize reporting unit exceeded its carrying value by approximately $36.0 and was therefore not impaired as of September 30, 2016. At September 30, 2016, the estimated fair values of all other reporting units exceeded their carrying values by at least 33% . As of September 30, 2015, the Company recorded a charge of $57.0 for the impairment of goodwill. The impairment charge related to the Active Nutrition segment and was primarily the result of fourth quarter production issues at Dymatize which resulted in the Company’s decision to close its manufacturing facility and permanently transfer production to third party facilities under co-manufacturing agreements. These fair value measurements fell within Level 3 of the fair value hierarchy as described in Note 14. The goodwill impairment losses are aggregated with trademark impairment losses in “Impairment of goodwill and other intangible assets” in the Consolidated Statements of Operations.

Equity Interests

Equity Interests	12 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity Interests	EQUITY INTERESTS In connection with its acquisition of the Weetabix Group in July 2017 (see Note 5), the Company acquired an equity interest in two legal entities, Alpen Food Company South Africa (Proprietary) Limited (“Alpen”) and Weetabix East Africa Limited (“Weetabix East Africa”). Results of both entities are reported in the Weetabix segment (see Note 21). 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. At September 30, 2017, the Company recorded an investment of $4.5 included in “Other assets” on the Consolidated Balance Sheet and loss of $0.1 included in “Other operating expenses, net” in the Consolidated Statement of Operations during the year ended September 30, 2017. At September 30, 2017, the Company had a receivable balance with Alpen of $1.0 , included in “Other assets” on the Consolidated Balance Sheet. 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, the Company has fully consolidated Weetabix East Africa into its consolidated financial statements. At September 30, 2017, Weetabix East Africa had a long-term payable with Pioneer Food Group Limited, the owner of the remaining 49.9% of the business, of $0.5 , included in “Other liabilities” on the Consolidated Balance Sheet.

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income taxes	INCOME TAXES The benefit for income taxes consisted of the following: Year Ended September 30, 2017 2016 2015 Current: Federal $ (5.8 ) $ 37.6 $ 59.5 State 4.3 1.7 2.9 Foreign 10.2 8.5 5.7 8.7 47.8 68.1 Deferred: Federal 19.7 (64.8 ) (116.0 ) State 2.7 (7.5 ) (2.1 ) Foreign (5.0 ) (2.3 ) (2.0 ) 17.4 (74.6 ) (120.1 ) Income tax expense (benefit) $ 26.1 $ (26.8 ) $ (52.0 ) The effective tax rate for fiscal 2017 was 35.1% compared to 89.0% for fiscal 2016 and 31.1% for fiscal 2015 . A reconciliation of income tax benefit with amounts computed at the statutory federal rate follows: Year Ended September 30, 2017 2016 2015 Computed tax at federal statutory rate (35%) $ 26.1 $ (10.5 ) $ (58.6 ) Non-deductible goodwill impairment loss 7.2 — 16.5 Non-deductible compensation 1.8 2.6 0.4 Non-deductible transaction costs 2.9 — 0.6 Domestic production activities deduction — (4.3 ) (5.9 ) State income taxes, net of effect on federal tax 0.8 (6.2 ) (7.2 ) Non-taxable interest income (3.4 ) (2.6 ) (2.7 ) Valuation allowances 4.8 3.8 6.7 Change in deferred tax rates — (2.0 ) 4.9 Uncertain tax positions (0.5 ) (2.0 ) (3.4 ) Sale and liquidation of Michael Foods Canadian egg business — (3.6 ) — Enacted tax law and changes — 0.7 (0.4 ) Income tax credits (1.4 ) (1.5 ) (0.4 ) Rate differential on foreign income (6.8 ) (1.8 ) (1.4 ) Excess tax benefits for share-based payments (6.2 ) — — Other, net (none in excess of 5% of statutory tax) 0.8 0.6 (1.1 ) Income tax expense (benefit) $ 26.1 $ (26.8 ) $ (52.0 ) Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax non-current assets (liabilities) were as follows: September 30, 2017 September 30, 2016 Assets Liabilities Net Assets Liabilities Net Accrued vacation, incentive and severance $ 16.2 $ — $ 16.2 $ 14.3 $ — $ 14.3 Inventory 3.0 — 3.0 2.5 — 2.5 Accrued liabilities 16.6 — 16.6 24.0 — 24.0 Property — (210.1 ) (210.1 ) — (172.3 ) (172.3 ) Intangible assets — (882.5 ) (882.5 ) — (784.3 ) (784.3 ) Pension and other postretirement benefits 5.3 — 5.3 31.7 — 31.7 Stock-based and deferred compensation 28.7 — 28.7 22.2 — 22.2 Derivative mark-to-market adjustments 91.9 — 91.9 121.6 — 121.6 Net operating loss carryforwards, credits 38.7 — 38.7 22.2 — 22.2 Other items 6.5 (1.6 ) 4.9 5.1 (1.3 ) 3.8 Total gross deferred income taxes 206.9 (1,094.2 ) (887.3 ) 243.6 (957.9 ) (714.3 ) Valuation allowance (18.5 ) — (18.5 ) (12.2 ) — (12.2 ) Total deferred taxes $ 188.4 $ (1,094.2 ) $ (905.8 ) $ 231.4 $ (957.9 ) $ (726.5 ) As of September 30, 2017 , the Company had United States federal net operating loss (“NOL”) carryforwards totaling approximately $96.8 which have expiration dates beginning in fiscal 2021 and extending through fiscal 2037 , as well as state NOL carryforwards totaling approximately $360.2 , which have expiration dates beginning in fiscal 2018 and extending through fiscal 2037 . As of September 30, 2017, Post had NOL carryforwards in foreign jurisdictions of $9.3 . As certain of these NOLs and carryforwards were acquired through acquisitions made during fiscal years 2013, 2014 and 2017, as a result of these ownership changes, the deductibility of the NOLs is subject to limitation under section 382 of the Internal Revenue Code (“IRC”) and similar limitations under state tax law. Giving consideration to IRC section 382 and state limitations, the Company believes it will generate sufficient taxable income to fully utilize the United States federal and certain state NOLs before they expire. Approximately $11.8 of the deferred tax asset related to the state NOLs has been offset by a valuation allowance based on management’s judgment that it is more likely than not that the benefits of those deferred tax assets will not be realized in the future. No provision has been made for income taxes on undistributed earnings of consolidated foreign subsidiaries of $56.4 at September 30, 2017 since it is our intention to indefinitely reinvest undistributed earnings of our foreign subsidiaries. It is not practicable to estimate the additional income taxes and applicable foreign withholding taxes that would be payable on the remittance of such undistributed earnings. For fiscal 2017 , 2016 and 2015 , foreign income before income taxes was $24.7 , $29.6 and $7.0 , respectively. Unrecognized Tax Benefits The Company recognizes the tax benefit from uncertain tax positions only if it is “more likely than not” the tax position will be sustained on examination by the taxing authorities. The tax benefits recognized from such positions are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. To the extent the Company’s assessment of such tax positions changes, the change in estimate will be recorded in the period in which the determination is made. Unrecognized tax benefits activity for the years ended September 30, 2017 and 2016 is presented in the following table: Unrecognized tax benefits, September 30, 2015 $ 11.3 Additions for tax positions taken in current year and acquisitions 0.1 Reductions for tax positions taken in prior years (1.6 ) Settlements with tax authorities/statute expirations (0.5 ) Unrecognized tax benefits, September 30, 2016 $ 9.3 Additions for tax positions taken in current year and acquisitions — Reductions for tax positions taken in prior years — Settlements with tax authorities/statute expirations (0.7 ) Unrecognized tax benefits, September 30, 2017 $ 8.6 The amount of the net unrecognized tax benefits that, if recognized, would directly affect the effective tax rate is $5.6 at September 30, 2017 . The Company believes that, due to expiring statutes of limitations and settlements with authorities, it is reasonably possible that the total unrecognized tax benefits may decrease by less than $1.0 within twelve months of the reporting date. The Company classifies tax-related interest and penalties as components of income tax expense. The accrued interest and penalties are not included in the table above. The Company had accrued interest and penalties of $2.7 and $2.4 at September 30, 2017 and 2016 , respectively. The Company had net expense (benefit) of $0.3 , $(0.1) and zero for interest and penalties in the Consolidated Statements of Operations for the years ended September 30, 2017 , 2016 and 2015 , respectively. Interest and penalties were computed on the difference between the tax position recognized for financial reporting purposes and the amount previously taken on the Company’s tax returns. United States federal, United States state and Canadian income tax returns for the tax years ended September 30, 2016 , 2015 and 2014 are subject to examination by the tax authorities in each respective jurisdiction. The Michael Foods tax return for the short year ended June 2, 2014 was examined by the Internal Revenue Service without adjustment. For the NPE acquisition made in 2017 and acquisitions made in 2015 , the seller generally retained responsibility for all income tax liabilities through the date of acquisition. With respect to the acquisition of the Weetabix Group, the Company assumed substantially all income tax liabilities for those jurisdictions which remain subject to examination. With respect to the Michael Foods acquisition, the Company assumed all income tax liabilities for those jurisdictions which remain subject to examination, consisting primarily of the short tax year ended June 2, 2014, the date of acquisition. The Company did not assume any pre-acquisition tax liabilities related to the 2016 acquisition of WEF.

Earnings (loss) per Share

Earnings (loss) per Share	12 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings (loss) per Share	EARNINGS (LOSS) PER SHARE Basic earnings (loss) per share is based on the average number of common shares outstanding during the period. Diluted earnings (loss) per share is based on the average number of shares used for the basic earnings (loss) per share calculation, adjusted for the dilutive effect of stock options, stock appreciation rights and restricted stock units using the “treasury stock” method. The impact of potentially dilutive convertible preferred stock is calculated using the “if-converted” method. For the periods outstanding, the Company’s tangible equity units (“TEUs”) (see Note 19) are assumed to be settled at the minimum settlement amount for weighted-average shares for basic earnings (loss) per share. All TEU purchase contracts were settled as of June 1, 2017. For diluted earnings (loss) per share, the shares, to the extent dilutive, are assumed to be settled as described in Note 19. Year ended September 30, 2017 2016 2015 Net earnings (loss) for basic loss per share $ 34.8 $ (28.4 ) $ (132.3 ) Net earnings (loss) for diluted loss per share $ 34.8 $ (28.4 ) $ (132.3 ) Weighted-average shares outstanding 65.2 63.9 51.8 Effect of TEUs on weighted-average shares for basic earnings (loss) per share 2.6 4.9 4.9 Weighted-average shares for basic earnings (loss) per share 67.8 68.8 56.7 Effect of dilutive securities: Stock options 1.8 — — Restricted stock awards 0.3 — — Total dilutive securities 2.1 — — Weighted-average shares for diluted earnings (loss) per share 69.9 68.8 56.7 Basic earnings (loss) per common share $ 0.51 $ (0.41 ) $ (2.33 ) Diluted earnings (loss) per common share $ 0.50 $ (0.41 ) $ (2.33 ) The following table details the securities that have been excluded from the calculation of weighted-average shares for diluted earnings (loss) per share as they were anti-dilutive. Year ended September 30, 2017 2016 2015 Stock options 0.3 4.3 4.2 Stock appreciation rights — 0.2 0.3 Restricted stock awards — 0.5 0.5 Preferred shares conversion to common 9.1 9.1 11.0

Supplemental Operations Stateme

Supplemental Operations Statement and Cash Flow Information	12 Months Ended
	Sep. 30, 2017
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, 2017 2016 2015 Advertising and promotion expenses $ 159.7 $ 184.2 $ 137.3 Repair and maintenance expenses 162.6 141.6 92.1 Research and development expenses 18.6 16.3 16.8 Rent expense 41.8 32.0 23.3 Interest income (6.8 ) (2.7 ) (0.8 ) Interest paid 333.6 309.6 235.5 Income taxes paid 29.6 73.4 46.4

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	12 Months Ended
	Sep. 30, 2017
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	SUPPLEMENTAL BALANCE SHEET INFORMATION September 30, 2017 2016 Receivables, net Trade $ 421.6 $ 354.9 Income tax receivable 46.4 23.6 Other 14.2 8.1 482.2 386.6 Allowance for doubtful accounts (1.6 ) (1.6 ) $ 480.6 $ 385.0 Inventories Raw materials and supplies $ 129.8 $ 112.4 Work in process 16.9 17.4 Finished products 395.6 339.3 Flocks 31.2 34.0 $ 573.5 $ 503.1 Other Assets Pension asset $ 154.6 $ — Other 29.7 15.9 $ 184.3 $ 15.9 Accounts Payable Trade $ 306.5 $ 228.8 Book cash overdrafts 17.8 26.6 Other 11.7 9.0 $ 336.0 $ 264.4 Other Current Liabilities Advertising and promotion $ 74.5 $ 95.8 Accrued interest 36.5 55.2 Accrued compensation 89.9 103.9 Hedging liabilities 54.6 5.5 Accrued legal settlements 8.6 37.3 Other 82.2 59.6 $ 346.3 $ 357.3 Other Liabilities Pension and other postretirement benefit obligations $ 83.5 $ 83.2 Hedging liabilities - non-current 188.9 313.2 Accrued compensation - non-current 29.2 22.7 Other 26.2 21.2 $ 327.8 $ 440.3

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts	12 Months Ended
	Sep. 30, 2017
Allowance for Doubtful Accounts [Abstract]
Allowance for Doubtful Accounts	ALLOWANCE FOR DOUBTFUL ACCOUNTS September 30, 2017 2016 2015 Balance, beginning of year $ 1.6 $ 2.0 $ 1.4 Provision charged to expense 0.3 1.2 0.7 Write-offs, less recoveries (0.3 ) (1.6 ) (0.3 ) Impact of acquisitions — — 0.2 Balance, end of year $ 1.6 $ 1.6 $ 2.0

Derivative Financial Instrument

Derivative Financial Instruments and Hedging	12 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Hedging	DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING In the ordinary course of business, the Company is exposed to commodity price risks relating to the acquisition of raw materials and supplies, interest rate risks relating to floating rate debt, and foreign currency exchange rate risks. The Company utilizes derivative financial instruments, including (but not limited to) futures contracts, option contracts, forward contracts and swaps, to manage certain of these exposures by hedging when it is practical to do so.The Company does not hold or issue financial instruments for speculative or trading purposes. At September 30, 2017 , the Company’s derivative instruments consisted of: Not designated as hedging instruments under ASC Topic 815 • Commodity and energy futures and option contracts which relate to inputs that generally will be utilized within the next year; • foreign currency forward contracts used to hedge the impact of intercompany activity against currency fluctuations between the United States dollar and Canadian dollar; • a pay-fixed, receive-variable interest rate swap maturing in May 2021 that requires monthly settlements and have the effect of hedging interest payments on debt expected to be issued but not yet priced; and • rate-lock interest rate swaps that require four lump sum settlements with the first settlement occurring in July 2018 and the last in July 2020 and have the effect of hedging interest payments on debt expected to be issued but not yet priced. Designated as hedging instruments under ASC Topic 815 • Foreign currency forward contracts used as a cash flow hedge of forecasted Euro denominated capital purchases occurring within the next 17 months against currency fluctuations between the Euro and the United States dollar; • a pay-fixed, receive-fixed cross-currency swap maturing in July 2022 that requires quarterly cash settlements used as a net investment hedge of the Company’s investment in the Weetabix Group, which is denominated in GBP; and • a pay-fixed, receive-variable interest rate swap maturing in May 2024 that requires monthly settlements used as a cash flow hedge of forecasted interest payments on our variable rate term loan (see Note 15). The following table shows the notional amounts of derivative instruments held. September 30, September 30, Not designated as hedging instruments under ASC Topic 815: Commodity contracts $ 53.8 $ 49.8 Energy contracts 25.6 23.6 Foreign exchange contracts - Forward contracts 3.8 — Interest rate swap 76.1 77.6 Interest rate swaps - Rate-lock swaps 1,649.3 1,649.3 Designated as hedging instruments under ASC Topic 815: Foreign exchange contracts - Forward contracts 20.9 — Foreign exchange contracts - Cross-currency swaps 448.7 — Interest rate swap 1,000.0 — The following tables present the balance sheet location and fair value of the Company’s derivative instruments on a gross and net basis as of September 30, 2017 and 2016 , along with the portion designated as hedging instruments under ASC Topic 815. The Company does not offset derivative assets and liabilities within the Consolidated Balance Sheets. Fair Value Portion Designated as Hedging Instruments Balance Sheet Location September 30, September 30, September 30, September 30, Asset Derivatives: Commodity contracts Prepaid expenses and other current assets $ 0.5 $ 0.6 $ — $ — Energy contracts Prepaid expenses and other current assets 3.8 2.4 — — Foreign exchange contracts Prepaid expenses and other current assets 1.3 — 1.1 — Foreign exchange contracts Other assets 0.3 — 0.3 — $ 5.9 $ 3.0 $ 1.4 $ — Liability Derivatives: Commodity contracts Other current liabilities $ 1.9 $ 3.3 $ — $ — Energy contracts Other current liabilities 0.3 0.2 — — Foreign exchange contracts Other current liabilities 1.5 — 1.5 — Foreign exchange contracts Other liabilities 23.6 — 23.6 — Interest rate swaps Other current liabilities 50.9 2.0 0.7 — Interest rate swaps Other liabilities 165.3 313.2 4.2 — $ 243.5 $ 318.7 $ 30.0 $ — The following tables present the effects of the Company’s derivative instruments on the Company’s Consolidated Statements of Operations for the years ended September 30, 2017 , 2016 and 2015 and Consolidated Statements of Comprehensive Income (Loss) as of September 30, 2017 and 2016 . Derivatives Not Designated as Hedging Instruments Statement of Operations Location (Gain) Loss Recognized in Statement of Operations 2017 2016 2015 Commodity contracts Cost of goods sold $ (0.4 ) $ 7.5 $ (5.2 ) Energy contracts Cost of goods sold (1.3 ) 1.2 12.8 Foreign exchange contracts Selling, general and administrative expenses 0.8 — — Interest rate swaps Other (income) expense, net (102.1 ) 182.9 92.5 Derivatives Designated as Hedging Instruments (Gain) Loss Recognized in OCI Loss Reclassified from Accumulated OCI into Earnings Loss Recognized in Earnings [amount excluded from effectiveness testing] Statement of Operations Location 2017 2016 2017 2016 2017 2016 Foreign exchange contracts $ (1.6 ) $ — $ — $ — $ — $ — Selling, general and administrative expenses Interest rate swaps 5.6 — 0.7 — — — Interest expense, net Cross-currency swaps (a) 14.8 — — — 10.3 — Other expense (income), net (a) On July 3, 2017, the Company designated its cross-currency swaps, entered into in the third quarter of fiscal 2017, as net investment hedges. Prior to the designation, mark to market losses of $10.3 were recognized in “Other expense (income), net” in the Consolidated Statement of Operations. Approximately $0.7 of the net cash flow hedge losses reported in accumulated OCI at September 30, 2017 is expected to be reclassified into earnings within the next 12 months. For gains and losses associated with foreign exchange forward contracts, the reclassification will occur on a straight-line basis over the useful life of the related capital assets. For gains or losses associated with interest rate swaps, the reclassification will occur over the term of the related debt. Reclassification of gains and losses reported in accumulated OCI related to the cross-currency swaps will only occur in the event all United Kingdom based operations are liquidated. At September 30, 2017 and September 30, 2016 , the Company had pledged collateral of $2.9 and $6.1 , respectively, related to its commodity and energy contracts. These amounts are classified as “Restricted cash” on the Consolidated Balance Sheets.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The following table presents the assets and liabilities measured at fair value on a recurring basis and the basis for that measurement according to the levels in the fair value hierarchy in ASC Topic 820: September 30, 2017 September 30, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Assets Deferred compensation investment $ 15.4 $ 15.4 $ — $ 11.5 $ 11.5 $ — Derivative assets 5.9 — 5.9 3.0 — 3.0 $ 21.3 $ 15.4 $ 5.9 $ 14.5 $ 11.5 $ 3.0 Liabilities Deferred compensation liabilities $ 22.5 $ — $ 22.5 $ 17.3 $ — $ 17.3 Derivative liabilities 243.5 — 243.5 318.7 — 318.7 $ 266.0 $ — $ 266.0 $ 336.0 $ — $ 336.0 The deferred compensation investment is primarily invested in mutual funds and its fair value is measured using the market approach. This investment is in the same funds and purchased in substantially the same amounts as the participants’ selected investment options (excluding Post common stock equivalents), which represent the underlying liabilities to participants in the Company’s deferred compensation plans. Deferred compensation liabilities are recorded at amounts due to participants in cash, based on the fair value of participants’ selected investment options (excluding certain Post common stock equivalents to be distributed in shares) using the market approach. The Company utilizes the income approach to measure fair value for its derivative assets, which include commodity options and futures contracts. The income approach uses pricing models that rely on market observable inputs such as yield curves and forward prices. Commodity and energy derivatives are valued using an income approach based on index prices less the contract rate multiplied by the notional amount. Foreign exchange contracts are valued using the spot rate less the forward rate multiplied by the notional amount. The Company’s calculation of the fair value of interest rate swaps is derived from a discounted cash flow analysis based on the terms of the contract and the interest rate curve. Refer to Note 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. 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 short-term and long-term debt at fair value on the Consolidated Balance Sheets. Based on current market rates, the fair value of the Company’s debt (Level 2) was $7,343.4 and $4,852.2 as of September 30, 2017 and 2016, respectively. Certain assets and liabilities, including long-lived assets, goodwill, indefinite-lived intangibles and assets held for sale are measured at fair value on a non-recurring basis. In fiscal 2017, the Company recorded goodwill impairment losses of $26.5 and goodwill and other intangible assets impairment losses of $57.0 and $3.8 , respectively, in the year ended September 30, 2015. There were no such charges recorded in fiscal 2016. These losses were recorded as “Impairment of goodwill and other intangible assets” in the Consolidated Statement of Operations. For additional information on other intangibles assets and goodwill, see Note 2 and Note 6, respectively. There were no other fair value measurement losses recognized during the years ended September 30, 2017, 2016 and 2015. At September 30, 2016, the Company had land, buildings and equipment classified as assets held for sale related to the closure of its Modesto, California facility. At September 30, 2016, the carrying value, as determined by estimated fair value less estimated costs to sell, of the assets held for sale was $4.3 and was included in “Prepaid expenses and other current assets” on the Condensed Consolidated Balance Sheets. Related to its Farmers Branch, Texas facility, the Company had land and buildings classified as assets held for sale as of September 30, 2016. The carrying value of the assets included in “Prepaid expenses and other current assets” on the Condensed Consolidated Balance Sheets was $5.8 as of September 30, 2016. The fair value of the assets held for sale were measured at fair value on a nonrecurring basis based on third party offers to purchase the assets. The fair value measurement was categorized as Level 3, as the fair values utilize significant unobservable inputs. The following table summarizes the Level 3 activity. For additional information on assets held for sale, see Note 4. Balance, September 30, 2015 $ 11.4 Transfers into held for sale 9.6 Losses on assets held for sale (9.3 ) Proceeds from the sale of assets held for sale (1.6 ) Balance, September 30, 2016 $ 10.1 Gain on sale of assets held for sale 0.2 Proceeds from the sale of assets held for sale (10.3 ) Balance, September 30, 2017 $ —

Long Term Debt

Long Term Debt	12 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Long-term Debt	LONG-TERM DEBT Long-term debt as of the dates indicated consists of the following: September 30, 2017 2016 5.50% Senior Notes maturing March 2025 $ 1,000.0 $ — 5.75% Senior Notes maturing March 2027 1,500.0 — 5.00% Senior Notes maturing August 2026 1,750.0 1,750.0 7.75% Senior Notes maturing March 2024 — 800.0 8.00% Senior Notes maturing July 2025 137.5 400.0 6.00% Senior Notes maturing December 2022 630.0 630.0 6.75% Senior Notes maturing December 2021 — 875.0 7.375% Senior Notes maturing February 2022 — 133.0 Term Loan 2,194.5 — TEUs (see Note 19) — 11.0 4.57% 2012 Series Bond maturing September 2017 — 1.3 Capital leases 0.2 — 7,212.2 4,600.3 Less: Current Portion (22.1 ) (12.3 ) Debt issuance costs, net (81.8 ) (53.5 ) Plus: Unamortized premium 40.8 16.7 Total long-term debt $ 7,149.1 $ 4,551.2 Senior Notes On June 2, 2014, the Company issued $630.0 principal value of 6.00% senior notes due in December 2022. The 6.00% senior notes were issued at par and the Company received $619.0 after paying related fees of $11.0 , which will be deferred and amortized to interest expense over the term of the notes. Interest payments on the 6.00% senior notes are due semi-annually each June 15 and December 15. On August 18, 2015, the Company issued $800.0 principal value of 7.75% senior notes due in March 2024 and $400.0 principal value of 8.00% senior notes due in July 2025. The 7.75% and 8.00% senior notes were issued at par. The Company received $1,187.9 after paying related fees of $12.1 , which were deferred to be amortized to interest expense over the term of the notes. Interest payments on the 7.75% senior notes were due semi-annually each March 15 and September 15. Interest payments on the 8.00% senior notes are due semi-annually each January 15 and July 15. With a portion of the proceeds received from term loan borrowings (see below), the Company repaid the $800.0 principal value of the 7.75% senior notes as well as $262.5 principal value of the 8.00% senior notes along with related tender premiums. In connection with the early repayment of these notes, the Company recorded expense of $160.4 in the year ended September 30, 2017, which is reported as “Loss on extinguishment of debt, net ” in the Consolidated Statement of Operations. This loss included tender premiums of $151.9 and debt issuance costs write-offs of $8.5 . On August 3, 2016, the Company issued $1,750.0 principal value of 5.00% senior notes due in August 2026. The 5.00% senior notes were issued at par and the Company received $1,725.7 after paying related fees of $24.3 , which were deferred and will be amortized to interest expense over the term of the notes. Interest payments on the 5.00% senior notes are due semi-annually each February 15 and August 15. On February 14, 2017, the Company issued $1,000.0 principal value of 5.50% senior notes due in March 2025 and $750.0 principal value of 5.75% senior notes due in March 2027 (the “February 14, 2017 issuance”). The 5.50% and 5.75% senior notes were issued at par and the Company received $1,725.4 after paying related fees of $24.6 , which were deferred and will be amortized to interest expense over the term of the notes. On August 10, 2017, the Company issued an additional $750.0 principal value of 5.75% notes due in March 2027. The additional 5.75% senior notes were issued at 105.5% of par value and the Company received $784.0 after paying investment banking and other fees of $7.2 . The premium related to the 5.75% senior notes will be amortized as a reduction to interest expense over the term of the notes. Interest payments on the the 5.50% and 5.75% senior notes are due semi-annually each March 1 and September 1. With a portion of the proceeds received from the issuance of the 5.00% senior notes, the Company repaid $1,242.0 principal value of the 7.375% senior notes, originally issued on February 3, 2012, October 25, 2012 and July 18, 2013. In connection with the early repayment of this portion of the 7.375% notes, the Company recorded expense of $78.6 in the year ended September 30, 2016, which was reported as “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations. This loss included a tender premium of $88.0 and debt issuance costs write-offs of $12.4 , partially offset by the write-off of unamortized debt premium of $21.8 . In addition, with a portion of the proceeds received from the February 14, 2017 issuance, the Company repaid the remaining $133.0 principal value of the 7.375% senior notes. In connection with the early repayment of this portion of the 7.375% notes, the Company recorded expense of $4.0 in the year ended September 30, 2017, which is reported as “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations. The loss included a premium of $4.9 and debt issuance costs write-offs of $1.2 , partially offset by the write-off of unamortized debt premium of $2.1 . With a portion of the proceeds received from the February 14, 2017 issuance, the Company repaid the $875.0 principal value of the 6.75% senior notes, originally issued on November 18, 2013 and March 19, 2014. In connection with the early repayment of these notes, the Company recorded expense of $58.5 in the year ended September 30, 2017, which is reported as “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations. The loss included a premium of $63.0 and debt issuance cost write-offs of $8.9 , partially offset by the write-off of unamortized debt premium of $13.4 . All of the Company’s senior notes are fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by each of our existing and future domestic subsidiaries, other than immaterial subsidiaries, receivables finance subsidiaries and subsidiaries we designate as unrestricted subsidiaries (the “Guarantors”). As of September 30, 2017, the U.S. subsidiary of the Weetabix Group was not a Guarantor, but the Company intends to add it as a Guarantor in the future. Our foreign subsidiaries do not guarantee the senior notes. These guarantees are subject to release in limited circumstances (only upon the occurrence of certain customary conditions). Credit Agreement On March 28, 2017, the Company amended and restated its prior credit agreement, originally entered into on January 29, 2014, and further amended the credit agreement on April 28, 2017 (as amended and restated, the “Credit Agreement”). The Credit Agreement provides for a revolving credit facility in an aggregate principal amount of $800.0 (the “Revolving Credit Facility”), with the commitments thereunder to be made available to the Company in US Dollars, Canadian Dollars, Euros and pounds sterling. The issuance of letters of credit is available under the Credit Agreement in an aggregate amount of up to $50.0 . The Credit Agreement also provides for potential incremental revolving and term facilities at the request of the Company and at the discretion of the lenders, in each case on terms to be determined, and also permits the Company, subject to certain conditions, to incur incremental equivalent debt, in an aggregate maximum amount not to exceed the greater of (1) $700.0 and (2) the maximum amount at which (A) the Company’s pro forma consolidated leverage ratio (as defined in the Credit Agreement) would not exceed 6.50 to 1.00 and (B) the Company’s pro forma senior secured leverage ratio (as defined in the Credit Agreement) would not exceed 3.00 to 1.00 as of the date such indebtedness is incurred. The outstanding amounts under the Revolving Credit Facility must be repaid on or before March 28, 2022. The Company incurred $4.6 of issuance costs in connection with the Credit Agreement in the year ended September 30, 2017. The Revolving Credit Facility has outstanding letters of credit of $10.0 which reduced the available borrowing capacity to $790.0 at September 30, 2017 . The Credit Agreement also permits the Company to incur additional unsecured debt if, among other conditions, its consolidated interest coverage ratio (as defined in the Credit Agreement) would be greater than or equal to 2.00 to 1.00 after giving effect to such new debt. Borrowings under the Revolving Credit Facility will bear interest, at the option of the Company, at an annual rate equal to either the Base Rate, Eurodollar Rate or Canadian Dollar Offered Rate (“CDOR”) (as such terms are defined in the Credit Agreement) plus an applicable margin ranging from 1.75% to 2.25% for Eurodollar Rate-based loans and CDOR Rate-based loans and from 0.75% to 1.25% for Base Rate-based loans, depending in each case on the Company’s senior secured leverage ratio. Commitment fees on the daily unused amount of commitments under the Revolving Credit Facility will accrue at rates ranging from 0.250% to 0.375% , also depending on the Company’s senior secured leverage ratio. The Credit Agreement contains affirmative and negative covenants customary for agreements of this type, including delivery of financial and other information, compliance with laws, maintenance of property, existence, insurance and books and records, inspection rights, obligation to provide collateral and guarantees by certain new subsidiaries, preparation of environmental reports, participation in an annual meeting with the agent and the lenders under the Credit Agreement, further assurances, limitations with respect to indebtedness, liens, fundamental changes, restrictive agreements, use of proceeds, amendments of organization documents, accounting changes, prepayments and amendments of certain indebtedness, dispositions of assets, acquisitions and other investments, sale leaseback transactions, conduct of business, transactions with affiliates, dividends and redemptions or repurchases of stock, and granting liens. The Credit Agreement contains a financial covenant requiring the Company to maintain a senior secured leverage ratio (as defined in the Credit Agreement) not to exceed 4.25 to 1.00, measured as of the last day of any fiscal quarter if, as of the last day of such fiscal quarter, the aggregate outstanding amount of all revolving credit loans, swing line loans and letter of credit obligations (subject to certain exceptions specified in the Credit Agreement) exceeds 30% of the Company’s revolving credit commitments. 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, indebtedness in excess of $75.0 , certain events of bankruptcy and insolvency, inability to pay debts, the occurrence of one or more unstayed or undischarged judgments in excess of $75.0 , attachments issued against a material part of the Company’s property, change in control, the invalidity of any loan document, the failure of the collateral documents to create a valid and perfected first priority lien and certain ERISA events. Upon the occurrence of an event of default, the maturity of the loans under the Credit Agreement may be accelerated 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 for the Company’s obligations under the Credit Agreement. The Company’s obligations under the Credit Agreement are unconditionally guaranteed by each of the Guarantors. The Company’s obligations under the Credit Agreement are secured by security interests on substantially all of the personal property assets of the Company and the Guarantors and are secured by the material domestic real property assets of the Company and the Guarantors. Term Loans On May 24, 2017, the Company entered into a Joinder Agreement No. 1 (“Joinder No. 1”). Joinder No.1 provided for an incremental term loan of $1,200.0 (the “ Joinder No. 1 Term Loan”) under the Credit Agreement. Pursuant to Joinder No. 1, the Company borrowed $1,200.0 , the net proceeds of which were used to repay the $800.0 principal value of the 7.75% senior notes as well as $262.5 principal value of the 8.00% senior notes along with related tender premiums and other fees and expenses (described above). On June 29, 2017, the Company entered into a Joinder Agreement No. 2 (“Joinder No. 2”). Joinder No. 2 provided for an incremental term loan of $1,000.0 (the “ Joinder No. 2 Term Loan”) under the Credit Agreement. Pursuant to Joinder No. 2, the Company borrowed $1,000.0 and used the proceeds, together with cash on hand, to finance its acquisition of the Weetabix Group (see Note 5). The Joinder No. 2 Term Loan was combined with the outstanding amounts under the Joinder No.1 Term Loan (collectively the “Term Loan”). The outstanding amounts under the Term Loan bear interest at the Eurodollar Rate plus 2.25% or the Base Rate (as such terms are defined in the Credit Agreement) plus 1.25% . The interest rate on the Term Loan at September 30, 2017 was 3.49% . The Term Loan requires quarterly principal installments of $5.5 beginning on September 30, 2017 and must be repaid in full on May 24, 2024. The Company must make certain prepayments of principal of the Term Loan under circumstances specified in Joinder No. 1. The Company incurred $23.7 of issuance costs in connection with the Term Loan as of September 30, 2017. In fiscal 2016 and 2015, the Company utilized a portion of the net proceeds from the issuances of the 7.75% senior notes, the 8.00% senior notes and the 5.00% senior notes, together with the net proceeds from the August 18, 2015 common stock issuance, to repay its prior term loan, originally entered into on June 2, 2014 and May 4, 2015. In connection with the early repayment of the prior term loan, the Company expensed $7.8 and $30.0 of debt issuance costs and unamortized debt discount in the years ended September 30, 2016 and 2015, respectively, which is reported as “Loss on extinguishment of debt, net” in the Consolidated Statement of Operations. Debt Covenants Under the terms of the Credit Agreement, the Company is required to comply with a financial covenant consisting of a ratio for quarterly maximum senior secured leverage (as defined in the Credit Agreement) not to exceed 4.25 to 1.00, measured as of the last day of any fiscal quarter if, as of the last day of such fiscal quarter, the aggregate outstanding amount of all revolving credit loans, swing line loans and letter of credit obligations (subject to certain exceptions specified in the Credit Agreement) exceeds 30% of the Company’s revolving credit commitments. As of September 30, 2017, the Company was not required to comply with such financial covenant as the aggregate amount of the aforementioned obligations did not exceed 30% . The Credit Agreement permits the Company to incur additional unsecured debt if, among other conditions, the pro forma consolidated interest coverage ratio, calculated as provided in the Credit Agreement, would be greater than or equal to 2.00 to 1.00 after giving effect to such new debt. As of September 30, 2017, the pro forma consolidated interest coverage ratio exceeded this threshold.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Legal Proceedings Antitrust claims: In late 2008 and early 2009, some 22 class action lawsuits were filed in various federal courts against Michael Foods, Inc. (“Michael Foods”), a wholly-owned subsidiary of the Company, and some 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 case involves three plaintiff groups: (1) direct purchasers of eggs and egg products; (2) companies (primarily large grocery chains and food companies that purchase considerable quantities of eggs) that opted out of any eventual class and brought their own separate actions against the defendants (“opt-out plaintiffs”); and (3) indirect purchasers of shell eggs. Motions related to class certification: In September 2015, the court granted the motion of the direct purchaser plaintiffs to certify a shell-egg subclass, but denied their motion to certify an egg-products subclass. Also in September 2015, the court denied the motion of the indirect purchaser plaintiffs for class certification. The indirect purchaser plaintiffs subsequently filed an alternative motion for certification of an injunctive class, and that motion was denied on June 27, 2017. Motions for summary judgment: In September 2016, the court granted the defendants’ motion for summary judgment based on purchases of egg products, thereby limiting all claims to shell eggs. Also in September 2016, the court denied individual motions for summary judgment made by Michael Foods and three other defendants that had sought the dismissal of all claims against them. Settlements by Michael Foods: On December 8, 2016, Michael Foods reached an agreement to settle all class claims asserted against it by the direct purchaser plaintiffs for a payment of $75.0 million . The Company has paid such amount into escrow. This settlement is awaiting court approval. Although the Company expects the settlement will receive the needed approval, there can be no assurance that the court will approve the agreement as proposed by the parties. On January 19, 2017, Michael Foods entered into a settlement, the details of which are confidential, with the opt-out plaintiffs (excluding those opt-out plaintiffs whose claims relate primarily or exclusively to egg products; several of those plaintiffs are now appealing the dismissal of the egg -products claims). This settlement was paid by the Company as of September 30, 2017. Michael Foods has at all times denied liability in this matter, and neither settlement contains any admission of liability by Michael Foods. Under current law, any settlement paid, including the settlement with the direct purchaser plaintiffs and the settlement with the opt-out plaintiffs, is deductible for federal income tax purposes. Remaining portions of the case: The Third Circuit Court of Appeals has denied the motions of the indirect purchaser plaintiffs to immediately appeal the court’s denial of their motions for class certification. Additionally, the elimination of egg products from the case is being appealed by opt-out plaintiffs who purchased egg products. The appeal is fully submitted to the Third Circuit Court of Appeals. Although the likelihood of a material adverse outcome in the egg antitrust litigation has been significantly reduced as a result of the Michael Foods settlements described above, there is still a possibility of an adverse outcome following appellate review of the remaining portions of the case. At this time, however, we do not believe it is possible to estimate any loss in connection with these remaining portions of the egg antitrust litigation. Accordingly, we cannot predict what impact, if any, these remaining matters and any results from such matters could have on our future results of operations. At September 30, 2016, the Company had accrued $28.5 for this matter that was included in “Other current liabilities” on the Consolidated Balance Sheets. There were no accruals for these matters at September 30, 2017. We record reserves for litigation losses in accordance with ASC Topic 450, “Contingencies” (“ASC 450”). Under ASC 450, a loss contingency is recorded if a loss is probable and can be reasonably estimated. We record probable loss contingencies based on the best estimate of the loss. If a range of loss can be reasonably estimated, but no single amount within the range appears to be a better estimate than any other amount within the range, the minimum amount in the range is accrued. These estimates are often initially developed earlier than when the ultimate loss is known, and the estimates are adjusted if additional information becomes known. Although the Company believes its accruals for this matter are appropriate, the final amounts required to resolve such matters could differ materially from recorded estimates and the Company's results of operations and cash flows could be materially affected. Accordingly, the Company cannot predict what impact, if any, these matters and any results from such matters could have on the future results of operations. During the years ended September 30, 2017 and 2016, the Company expensed $74.5 and $28.5 related to these settlements, respectively, which was included in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. No expense related to these settlements was recorded during the year ended September 30, 2015. 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 position, 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 position, results of operations or cash flows of the Company. Lease Commitments Future minimum rental payments under noncancelable operating leases in effect as of September 30, 2017 were $22.4 , $25.3 , $23.7 , $22.8 , $20.6 and $38.1 for fiscal 2018 , 2019 , 2020 , 2021 , 2022 and thereafter, respectively.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	12 Months Ended
	Sep. 30, 2017
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension and Other Postretirement Benefits	PENSION AND OTHER POSTRETIREMENT BENEFITS The Company maintains qualified defined benefit plans in the United States, United Kingdom 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 U.S. Post Consumer Brands employees, eligibility is frozen to new employees and benefit accruals are frozen for all administrative employees and certain production employees. 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 Weetabix employees, eligibility is frozen to new entrants in the United Kingdom and the benefit accrual is frozen for salaried Weetabix employees in the United States and in the executive scheme for United Kingdom employees. 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, 2017 , and a statement of the funded status and amounts recognized on the combined balance sheets as of September 30, 2017 and 2016. North America Other International Year Ended Year Ended 2017 2016 2017 2016 Change in benefit obligation Benefit obligation at beginning of period $ 71.2 $ 58.1 $ — $ — Service cost 4.1 4.0 1.7 — Interest cost 2.5 2.5 4.9 — Plan participants’ contributions 0.6 0.6 0.6 — Plan amendment (a) — 0.5 — — Actuarial loss (gain) (1.0 ) 8.0 (46.4 ) — Business combinations 25.5 — 746.0 — Benefits paid (3.0 ) (2.7 ) (6.2 ) — Currency translation 0.7 0.2 23.0 — Benefit obligation at end of period $ 100.6 $ 71.2 $ 723.6 $ — Change in fair value of plan assets Fair value of plan assets at beginning of period $ 54.3 $ 44.4 $ — $ — Actual return on plan assets 5.4 5.5 0.3 — Employer contributions 7.7 6.3 2.4 — Business combinations 15.2 — 852.2 — Plan participants’ contributions 0.6 0.6 0.6 — Benefits paid (3.0 ) (2.7 ) (6.2 ) — Currency translation 0.7 0.2 27.4 — Fair value of plan assets at end of period 80.9 54.3 876.7 — Funded status $ (19.7 ) $ (16.9 ) $ 153.1 $ — Amounts recognized in assets or liabilities Other assets $ 1.5 $ — $ 153.1 $ — Other liabilities (21.2 ) (16.9 ) — — Net amount recognized $ (19.7 ) $ (16.9 ) $ 153.1 $ — Amounts recognized in accumulated other comprehensive loss Net actuarial loss $ 0.6 $ 19.1 $ (40.2 ) $ — Prior service cost (credit) 14.3 0.8 — — Total $ 14.9 $ 19.9 $ (40.2 ) $ — Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 3.86 % 3.66 % n/a n/a Discount rate — Canadian plans 3.63 % 3.18 % n/a n/a Discount rate — Other international plans n/a n/a 2.72 % n/a Rate of compensation increase — U.S. plans 3.00 % 3.00 % n/a n/a Rate of compensation increase — Canadian plans 2.69 % 2.75 % n/a n/a Rate of compensation increase — Other international plans n/a n/a 2.70 % n/a (a) In the second quarter of fiscal 2016, the Company finalized a new collective bargaining agreement that resulted in an amendment to its North American pension plans. The accumulated benefit obligation exceeded the fair value of plan assets for the North American pension plans at September 30, 2017 and September 30, 2016 , whereas the fair value of plan assets for the Other International pension plans exceeded the accumulated benefit obligation at September 30, 2017 . The aggregate accumulated benefit obligation for the North American pension plans was $98.3 and $68.6 at September 30, 2017 and 2016, respectively. The aggregate accumulated benefit obligation for the Other International pension plans was $690.4 at September 30, 2017 . The following tables provide the components of net periodic benefit cost for the pension plans including amounts recognized in OCI. North America Year Ended September 30, 2017 2016 2015 Components of net periodic benefit cost Service cost $ 4.1 $ 4.0 $ 3.8 Interest cost 2.5 2.5 2.2 Expected return on plan assets (3.2 ) (2.6 ) (2.4 ) Recognized net actuarial loss 1.6 1.1 0.9 Recognized prior service cost 0.2 0.3 0.3 Net periodic benefit cost $ 5.2 $ 5.3 $ 4.8 Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans 3.66 % 4.55 % 4.56 % Discount rate — Canadian plans 3.18 % 3.82 % 4.25 % Rate of compensation increase — U.S. plans 2.99 % 3.00 % 3.00 % Rate of compensation increase — Canadian plans 2.50 % 2.75 % 2.75 % Expected return on plan assets — U.S. plans 5.33 % 5.20 % 5.72 % Expected return on plan assets — Canadian plans 6.00 % 6.00 % 6.00 % Changes in benefit obligation recognized in Total Comprehensive Income (Loss) Net (gain) loss $ (3.1 ) $ 5.1 $ 6.4 Recognized loss (1.6 ) (1.1 ) (0.9 ) Plan amendment — 0.5 — Recognized prior service cost (0.2 ) (0.3 ) (0.3 ) Currency translation (0.1 ) — — Total recognized in other comprehensive income or loss (before tax effects) $ (5.0 ) $ 4.2 $ 5.2 Other International Year Ended September 30, 2017 2016 2015 Components of net periodic benefit cost Service cost $ 1.7 $ — $ — Interest cost 4.9 — — Expected return on plan assets (7.5 ) — — Net periodic benefit cost $ (0.9 ) $ — $ — Weighted-average assumptions used to determine net benefit cost Discount rate 2.61 % — % — % Rate of compensation increase 2.75 % — % — % Expected return on plan assets 3.52 % — % — % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income (Loss) Net (gain) loss $ (39.3 ) $ — $ — Currency translation (0.9 ) — — Total recognized in other comprehensive income or loss (before tax effects) $ (40.2 ) $ — $ — The estimated net actuarial loss and prior service cost expected to be reclassified from accumulated OCI into net periodic benefit cost during 2018 related to North American pension benefits are $1.1 and $0.1 , respectively. There are no estimated net actuarial loss and prior service cost (credit) expected to be reclassified from accumulated OCI into net periodic benefit cost during 2018 related to Other International pension benefits. In addition, the Company expects to make contributions of $5.2 and $9.6 to its defined benefit North American and Other International pension plans, respectively, during fiscal 2018 . The expected return on North American pension plan assets was determined based on historical and expected future returns of the various asset classes, using the target allocation. The broad target allocations are 56.0% equity securities, 40.0% debt securities and 4.0% real assets. At September 30, 2017 , equity securities were 58.3% , debt securities were 37.0% , real assets were 3.7% and other was 1.0% of the fair value of total plan assets, approximately 69.6% of which was invested in passive index funds. At September 30, 2016 , equity securities were 49.8% , debt securities were 42.4% , real assets were 6.6% and cash was 1.2% of the fair value of total plan assets, approximately 81.0% 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 63.0% debt securities, 22.8% liability driven instruments, 4.0% real assets, 8.0% other and 2.2% cash. At September 30, 2017 , debt securities were 75.9% , liability hedging instruments were 23.3% , real assets were 0.4% , other was 0.1% and cash was 0.3% of the fair value of total plan assets, approximately 25.6% of which was invested in passive index funds. The allocation guidelines were established based on management’s determination of the appropriate risk posture and long-term objectives. The following tables present the North American and Other International pension plan’s assets measured at fair value on a recurring basis and the basis for that measurement. The fair value of mutual funds is based on quoted net asset values of the shares held by the plan at year end. North America September 30, 2017 September 30, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Equities $ 16.4 $ 7.8 $ 8.6 $ 6.7 $ — $ 6.7 Bonds 11.3 11.3 — 6.0 6.0 — Fixed income 4.6 — 4.6 3.9 — 3.9 Real assets 0.9 0.9 — — — — Cash 0.8 0.8 — 0.6 0.6 — Fair value of plan assets in the fair value hierarchy 34.0 20.8 13.2 17.2 6.6 10.6 Equities 30.7 — — 20.3 — — Pooled assets 4.5 — — 4.3 — — Fixed income 9.6 — — 8.9 — — Real assets 2.1 — — 3.6 — — Investments measured at net asset value (a) 46.9 — — 37.1 — — Total plan assets $ 80.9 $ 20.8 $ 13.2 $ 54.3 $ 6.6 $ 10.6 Other International September 30, 2017 Total Level 1 Level 2 Bonds $ 461.7 $ 441.1 $ 20.6 Liability driven instruments 204.2 204.2 — Fixed income 108.3 108.3 — Cash 2.7 2.7 — Fair value of plan assets in the fair value hierarchy 776.9 756.3 20.6 Fixed income 95.0 — — Real assets 3.9 — — Other 0.9 — — Investments measured at net asset value (a) 99.8 — — Total plan assets $ 876.7 $ 756.3 $ 20.6 (a) In accordance with ASC 820-10, certain investments were measured at net asset value per share (“NAV”). In cases where the fair value was measured at NAV using the practical expedient provided for in ASC 820-10, the investments have not been classified in the fair value hierarchy. The fair value amounts presented in these tables are intended to permit reconciliation of the fair value hierarchy to the tables above. Other Postretirement Benefits The following table provides a reconciliation of the changes in the North American other postretirement benefit obligations over the two year period ended September 30, 2017 . Besides the North American plans, the Company does not maintain any other postretirement benefit plans. Year Ended 2017 2016 Change in benefit obligation Benefit obligation at beginning of period $ 68.6 $ 112.4 Service cost 0.6 1.0 Interest cost 2.0 4.0 Plan amendment (a) (0.1 ) (36.1 ) Actuarial gain (4.4 ) (11.3 ) Benefits paid (2.1 ) (1.6 ) Currency translation 0.4 0.2 Benefit obligation at end of period $ 65.0 $ 68.6 Change in fair value of plan assets Employer contributions 2.1 1.6 Benefits paid (2.1 ) (1.6 ) Fair value of plan assets at end of period — — Funded status $ (65.0 ) $ (68.6 ) Amounts recognized in assets or liabilities Other current liabilities (2.7 ) (2.3 ) Other liabilities (62.3 ) (66.3 ) Net amount recognized $ (65.0 ) $ (68.6 ) Amounts recognized in accumulated other comprehensive loss Net actuarial loss $ 8.6 $ 13.6 Prior service cost (credit) (28.8 ) (33.5 ) Total $ (20.2 ) $ (19.9 ) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 3.77 % 3.54 % Discount rate — Canadian plans 3.69 % 3.23 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % (a) In the second quarter of fiscal 2016, the Company finalized a new collective bargaining agreement that resulted in an amendment to its pension and other postretirement benefit plans. The following table provides the components of net periodic benefit cost for the other postretirement benefit plans including amounts recognized in OCI. Year Ended September 30, 2017 2016 2015 Components of net periodic benefit cost Service cost $ 0.6 $ 1.0 $ 2.0 Interest cost 2.0 4.0 4.8 Recognized net actuarial loss 0.7 1.6 1.4 Recognized prior service credit (4.8 ) (3.8 ) (1.6 ) Net periodic benefit cost $ (1.5 ) $ 2.8 $ 6.6 Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans (Prior to plan amendment) (a) n/a 4.60 % 4.61 % Discount rate — U.S. plans (Subsequent to plan amendment) (a) 3.54 % 4.22 % n/a Discount rate — Canadian plans 3.23 % 3.91 % 4.45 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % 2.75 % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income (Loss) Net (gain) loss $ (4.4 ) $ (11.3 ) $ 3.1 Recognized loss (0.7 ) (1.6 ) (1.4 ) Plan amendment (0.1 ) (36.1 ) — Recognized prior service credit 4.8 3.8 1.6 Currency translation 0.1 (0.1 ) (0.3 ) Total recognized in other comprehensive income or loss (before tax effects) $ (0.3 ) $ (45.3 ) $ 3.0 (a) The plan was re-measured as of February 29, 2016. For fiscal 2016, the discount rate was 4.6% for the first five months of benefit cost and 4.22% for the last seven months of benefit cost. For September 30, 2017 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to domestic plans for 2018 was 7.0% and 5.8% for participants under the age of 65 and over the age of 65, respectively, declining gradually to an ultimate rate of 5.0% for 2022 and beyond. For September 30, 2016 measurement purposes, the assumed annual rate of increase in the future per capita cost of covered health care benefits related to domestic plans for 2017 was 7.5% and 6.0% for participants under the age of 65 and over the age of 65, respectively, declining gradually to an ultimate rate of 5.0% for 2022 and beyond. For September 30, 2017 and 2016 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 6.5% and 7.0% , respectively, declining gradually to an ultimate rate of 4.5% for 2021 and beyond for the year ended September 30, 2017 and 2016. A 1% change in assumed health care cost trend rates would result in the following changes in the accumulated postretirement benefit obligation and in the total service and interest cost components for fiscal 2017 : Increase Decrease Effect on postretirement benefit obligation $ 6.7 $ (5.5 ) Effect on total service and interest cost 0.3 (0.2 ) The estimated net actuarial loss and prior service credit expected to be reclassified from accumulated OCI into net periodic benefit cost during 2018 related to other postretirement benefits are $0.3 and $4.7 , respectively. Additional Information As of September 30, 2017 , expected future benefit payments and related federal subsidy receipts (Medicare Part D) in the next ten fiscal years were as follows: 2018 2019 2020 2021 2022 2023- 2027 Pension benefits $ 23.0 $ 24.2 $ 24.6 $ 25.5 $ 26.8 $ 153.3 Other benefits 2.7 3.0 3.2 3.3 3.5 18.2 Subsidy receipts — — 0.1 0.1 0.1 1.0 In addition to the defined benefit plans described above, the Company sponsors a defined contribution 401(k) plan under which it makes matching contributions. The Company expensed $ 18.2 , $ 15.6 and $ 11.7 for the fiscal years ended September 30, 2017 , 2016 and 2015 , respectively.

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Sep. 30, 2017
Stock-Based Compensation [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION On February 3, 2012, the Company established the 2012 Long-Term Incentive Plan (the “2012 Plan”) which permitted the issuance of various stock-based compensation awards up to 6.5 million shares. On January 29, 2016, the Company established the 2016 Long-Term Incentive Plan (the “2016 Plan”) which permits issuance of stock-based compensation awards up to 2.4 million shares. Upon establishment of the 2016 Plan, all remaining shares available to be issued under the 2012 Plan were transfered to the 2016 Plan. Awards issued under the 2012 Plan and 2016 Plan have a maximum term of 10 years, provided, however, that the Corporate Governance and Compensation Committee of the Board of Directors may, in its discretion, grant awards with a longer term to participants who are located outside the United States. Total compensation cost for cash and non-cash stock-based compensation awards recognized in the fiscal years ended 2017 , 2016 and 2015 was $30.7 , $25.6 and $29.2 , respectively, and the related recognized deferred tax benefit for each of those periods was approximately $9.7 , $8.0 and $10.6 , respectively. As of September 30, 2017 , the total compensation cost related to non-vested awards not yet recognized was $44.4 , which is expected to be recognized over a weighted-average period of 2.2 years. In connection with employee retirement and reorganization initiatives during fiscal 2015, the Company accelerated the vesting of unvested equity awards for 25 and 4 employees in the fiscal years ended September 2016 and 2015, respectively. As a result of this acceleration, the Company recorded $2.2 and $8.0 of incremental cash and stock-based compensation expense in the fiscal years ended September 30, 2016 and 2015, respectively. No such expense was recorded in the year ended September 30, 2017. Stock Appreciation Rights Information about stock-settled stock appreciation rights (“SSAR”) is summarized in the following table. Upon exercise of each SSAR, the holder will receive the number of shares of Post common stock equal in value to the difference between the exercise price and the fair market value at the date of exercise, less all applicable taxes. The total intrinsic value of SSARs exercised was $0.6 , $5.1 and $2.1 in the fiscal years ended September 30, 2017 , 2016 and 2015 , respectively. Stock-Settled Stock Appreciation Rights Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2016 152,831 $ 42.07 Granted — — Exercised (15,000 ) 46.19 Forfeited — — Expired — — Outstanding at September 30, 2017 137,831 41.63 5.69 $ 6.4 Vested and expected to vest as of September 30, 2017 137,831 41.63 5.69 6.4 Exercisable at September 30, 2017 102,831 38.17 5.08 5.2 In 2015, the Company granted 40,000 SSARs to its non-management members of the Board of Directors. Due to vesting provisions of these awards the Company determined that these awards had subjective acceleration rights such that the Company expensed the grant date fair value upon issuance and recognized $0.7 of related expense for the year ended September 30, 2015. The following table provides the weighted-average grant date fair value of SSARs granted calculated using the Black-Scholes valuation model, which uses assumptions of expected life (term), expected stock price volatility, risk-free interest rate, and expected dividends (collectively, the “Black-Scholes Model”). The expected term is estimated based on the award’s vesting period and contractual term, along with historical exercise behavior on similar awards. Expected volatilities are based on historical volatility trends. The risk-free rate is the interpolated U.S. Treasury rate for a term equal to the expected term. The weighted-average assumptions and grant date fair values for SSARs granted during the fiscal year ended September 30, 2015 are summarized in the table below. For SSARs granted to Company employees prior to the separation from its former owner, the assumptions used in the Black-Scholes Model were based on the former owner’s history and stock characteristics. 2015 Expected term (in years) 6.5 Expected stock price volatility 29.2% Risk-free interest rate 1.6% Expected dividends 0% Fair value (per SSAR) $16.72 Cash Settled Stock Appreciation Rights Cash-Settled Stock Appreciation Rights Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2016 105,000 $ 46.29 Granted — — Exercised (500 ) 18.10 Forfeited — — Expired — — Outstanding at September 30, 2017 104,500 46.43 7.40 $ 4.4 Vested and expected to vest as of September 30, 2017 104,500 46.43 7.40 4.4 Exercisable at September 30, 2017 71,166 45.83 7.31 3.0 The fair value of each cash settled stock appreciation right (“SAR”) was estimated each reporting period using the Black-Scholes Model. The expected term is estimated based on the award’s vesting period and contractual term, along with historical exercise behavior on similar awards. Expected volatilities are based on historical volatility trends and other factors. The risk-free rate is the interpolated U.S. Treasury rate for a term equal to the expected term. The following table presents the assumptions used to remeasure the fair value of outstanding SARs at September 30, 2017 , 2016 and 2015 . 2017 2016 2015 Expected term 2.9 3.8 4.8 Expected stock price volatility 31.7% 32.4% 29.7% Risk-free interest rate 1.6% 1.0% 1.3% Expected dividends 0% 0% 0% Fair value (per right) $54.18 $44.44 $29.10 Stock Options Stock Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2016 4,255,500 $ 42.15 Granted 343,000 71.32 Exercised (400,000 ) 33.51 Forfeited — — Expired — — Outstanding at September 30, 2017 4,198,500 45.36 6.29 $ 180.2 Vested and expected to vest as of September 30, 2017 4,198,500 45.36 6.29 180.2 Exercisable at September 30, 2017 3,060,163 41.00 5.76 144.7 The fair value of each stock option was estimated on the date of grant using the Black-Scholes Model. The Company uses the simplified method for estimating a stock option term as it does not have sufficient historical share options exercise experience upon which to estimate an expected term. The expected term is estimated based on the award’s vesting period and contractual term, along with historical exercise behavior on similar awards. Expected volatilities are based on historical volatility trends and other factors. The risk-free rate is the interpolated U.S. Treasury rate for a term equal to the expected term. The weighted-average assumptions and fair values for stock options granted during the years ended September 30, 2017 , 2016 and 2015 are summarized in the table below. 2017 2016 2015 Expected term 6.5 6.5 5.3 Expected stock price volatility 30.6% 29.1% 27.9% Risk-free interest rate 1.9% 1.9% 1.6% Expected dividends 0% 0% 0% Fair value (per option) $24.80 $20.22 $7.22 The total intrinsic value of stock options exercised was $17.6 , $5.1 and $12.4 in the fiscal years ended September 30, 2017 , 2016 and 2015 , respectively. Restricted Stock Units Restricted Stock Units Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2016 543,502 $ 54.11 Granted 342,778 73.79 Vested (136,557 ) 51.60 Forfeited (19,683 ) 63.84 Nonvested at September 30, 2017 730,040 63.55 The grant date fair value of each restricted stock award was determined based upon the closing price of the Company’s stock on the date of grant. The total vest date fair value of restricted stock units that vested during fiscal 2017 , 2016 and 2015 was $10.5 , $32.0 and $9.3 , respectively. In fiscal years 2017 and 2016 , the Company granted 10,200 and 15,000 restricted stock units to its non-management members of the Board of Directors, respectively. Due to vesting provisions of these awards, the Company determined that 8,500 and 12,500 of these awards granted in 2017 and 2016, respectively, had subjective acceleration rights such that the Company expensed the grant date fair value upon issuance and recognized $0.7 of related expense in each of the years ended September 30, 2017 and 2016 , respectively. Cash Settled Restricted Stock Units Cash-Settled Restricted Stock Units Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2016 154,230 $ 47.66 Granted — — Vested (51,919 ) 44.41 Forfeited (2,192 ) 42.37 Nonvested at September 30, 2017 100,119 49.47 Cash settled restricted stock awards are liability awards and as such, their fair value is based upon the closing price of the Company’s stock for each reporting period, with the exception of 49,000 cash settled restricted stock units that are valued at the greater of the closing stock price or the grant price of $51.43 . Cash used by the Company to settle restricted stock units was $4.1 , $5.9 and $3.4 for the years ended September 30, 2017 , 2016 and 2015 , respectively. Deferred Compensation Post provides deferred compensation plans for directors and key employees through which eligible participants may elect to defer payment of all or a portion of their compensation or eligible annual bonus until a later date based on the participant’s elections. Participant deferrals for employee participants may be made into Post common stock equivalents (Equity Option) or into a number of funds operated by The Vanguard Group Inc. with a variety of investment strategies and objectives (Vanguard Funds). In order to receive a 33% matching contribution, deferrals for director participants must be made into Post common stock equivalents. Deferrals into the Equity Option are generally distributed in Post stock for employees and cash for directors, while deferrals into the Vanguard Funds are distributed in cash. There are no significant costs related to the administration of the deferred compensation plans. Post funds its deferred compensation liability (potential cash distributions) by investing in the Vanguard Funds in 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 Statement of Operations and offset the related change in the deferred compensation liability. For additional information, refer to Note 14.

Tangible Equity Units Tangible

Tangible Equity Units Tangible Equity Units	12 Months Ended
	Sep. 30, 2017
Tangible Equity Units [Abstract]
Tangible Equity Units	TANGIBLE EQUITY UNITS In May 2014, the Company completed a public offering of 2.875 million TEUs, each with a stated value of $100.00 . Each TEU was comprised of a prepaid stock purchase contract and a senior amortizing note due June 1, 2017. The prepaid common stock purchase contracts were recorded as additional paid-in capital, net of issuance costs, and the senior notes were recorded as long-term debt. Issuance costs associated with the debt component were recorded as deferred financing costs within “Long-term debt” on the Consolidated Balance Sheets and were amortized using the effective interest rate method over the term of the instrument to June 1, 2017. Post allocated the proceeds from the issuance of the TEUs to equity and debt based on the relative fair values of the respective components of each TEU. The proceeds received in the offering were $278.6 , which were net of financing fees of $8.9 . The aggregate values assigned upon issuance of each component of the TEUs were as follows (amounts in millions except price per TEU): Equity Component Debt Component TEUs Total Price per TEU $ 85.48 $ 14.52 $ 100.00 Gross proceeds $ 245.7 $ 41.8 $ 287.5 Issuance costs (7.6 ) (1.3 ) (8.9 ) Net proceeds $ 238.1 $ 40.5 $ 278.6 Balance sheet impact (at issuance) Long-term debt (deferred financing fees) $ — $ 1.3 $ 1.3 Current portion of long-term debt — 13.3 13.3 Long-term debt — 28.5 28.5 Additional paid-in capital 238.1 — 238.1 The senior amortizing note component of each TEU’s initial principal amount of $14.5219 bore interest at 5.25% per annum and had a final installment payment date on June 1, 2017. The Company paid equal quarterly cash installments of $1.3125 per amortizing note on March 1, June 1, September 1 and December 1 of each year. Payments commenced on September 1, 2014 and ended on June 1, 2017. Each installment constituted a payment of interest and a partial repayment of principal. The senior amortizing note component of the TEUs was repaid as of June 1, 2017 and the Company delivered 1.7114 shares of its common stock per purchase contract. Holders of TEUs, or their separated purchase contract components, settled 2.8 and 0.1 purchase contracts during the years ended September 30, 2017 and 2016, respectively, for which the Company issued 4.7 and 0.2 shares of common stock during the years ended September 30, 2017 and 2016, respectively. No purchase contracts were settled and no shares of common stock were issued relating to the TEUs during the year ended September 30, 2015. All outstanding purchase contracts were settled as of September 30, 2017.

Stockholders' Equity Stockholde

Stockholders' Equity Stockholders' Equity	12 Months Ended
	Sep. 30, 2017
Stockholders' Equity Attributable to Parent [Abstract]
Shareholders' Equity	SHAREHOLDERS' EQUITY The Company has two classes of preferred stock, the 3.75% Series B Cumulative Perpetual Convertible Preferred Stock (the “Series B Preferred”) and the 2.5% Series C Cumulative Perpetual Convertible Preferred Stock (the “Series C Preferred”). There are 50.0 preferred shares authorized. The Series B Preferred has a $0.01 par value per share and a $100.00 liquidation value per share. There were 1.5 shares outstanding at both September 30, 2017 and 2016 . The Series B Preferred earns cumulative dividends at a rate of 3.75% per annum payable quarterly on February 15, May 15, August 15 and November 15. The Series B Preferred is non-voting and ranks senior to the Company’s outstanding common stock upon the Company’s dissolution or liquidation. The Series B Preferred has no maturity date; however, holders of the Series B Preferred may convert their stock at an initial conversion rate of 2.1192 shares of the Company’s common stock per share of convertible preferred stock, which is equivalent to a conversion price of $47.19 per share of common stock. On or after February 15, 2018, the Company may redeem all or some of the Series B Preferred at a redemption price equal to 100% of the liquidation preference per share, plus accrued and unpaid dividends to the redemption date if the closing sale price of our common stock has been at least 130% of the conversion price then in effect for at least 20 trading days during any 30 day trading day period ending on, and including, the trading day immediately preceding the date of the redemption notice. The Series C Preferred has a $0.01 par value per share and a $100.00 liquidation value per share. There were 3.2 shares outstanding at both September 30, 2017 and 2016 . The Series C Preferred earns cumulative dividends at a rate of 2.5% per annum payable quarterly on February 15, May 15, August 15 and November 15. The Series C Preferred is non-voting and ranks senior to the Company’s outstanding common stock upon the Company’s dissolution or liquidation. The Series C Preferred has no maturity date; however, holders of the Series C Preferred may convert their stock at an initial conversion rate of 1.8477 shares of the Company’s common stock per share of convertible preferred stock, which is equivalent to a conversion price of $54.12 per share of common stock. On or after February 15, 2019, the Company may redeem all or some of the Series C Preferred at a redemption price equal to 100% of the liquidation preference per share, plus accrued and unpaid dividends to the redemption date if the closing sale price of our common stock has been at least 150% of the conversion price then in effect for at least 20 trading days during any 30 day trading day period ending on, and including, the trading day immediately preceding the date of the redemption notice. Fiscal 2017 During the year ended September 30, 2017, the Company repurchased 4.0 shares of its common stock at an average share price of $79.53 per share for a total cost of $317.8 , including brokers’ commissions. These share repurchases were recorded as “Treasury stock, at cost” on the Consolidated Balance Sheets. Fiscal 2016 In December 2015, the Company and a holder of the Company’s Series B Preferred entered into an exchange agreement pursuant to which the shareholder agreed to deliver 0.9 shares of the Series B Preferred to the Company in exchange for 2.0 shares of common stock and $10.9 of cash. The number of shares of common stock exchanged in the transaction was based upon the current conversion rate, under the Certificate of Designation, Rights and Preferences for the Series B Preferred, of 2.1192 shares of common stock per share of Series B Preferred. The cash paid of $10.9 was recorded as “Additional paid-in capital” on the Consolidated Balance Sheet. 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 pre-determined 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 pre-determined 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 pre-determined price, the Company will receive the number of shares specified in the agreement. In March 2016, the Company entered into a structured share repurchase arrangement which required cash payments totaling $28.3 , including transaction-related fees of $0.2 . At the May 2016 expiration of the agreement, the market price of Post’s common stock exceeded the pre-determined contract price, resulting in cash payments to the Company of $29.4 . Prepayments and cash receipts at settlement under the agreement were recorded as “Additional paid-in capital” on the Consolidated Balance Sheets.

Segments

Segments	12 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segments	SEGMENTS During the fourth quarter of fiscal 2017, we reorganized our reportable segments in accordance with ASC Topic 280, “Segment Reporting.” At September 30, 2017, our reportable segments were as follows: • Post Consumer Brands: North American RTE cereal and granola businesses, inclusive of the recently acquired Weetabix North American RTE cereal business; • Michael Foods Group: eggs, potatoes, cheese and pasta; • Active Nutrition: protein shakes, bars and powders and nutritional supplements; • Private Brands: peanut and other nut butters and dried fruit and nuts; and • Weetabix: the Weetabix branded RTE cereal and Alpen branded muesli business sold and distributed primarily outside of North America. All historical segment results reported herein have been reclassified to conform with the September 30, 2017 presentation. Management evaluates each segment’s performance based on its segment profit, which is its operating profit before impairment of property and intangible assets, facility closure related costs, restructuring expenses, losses on assets held for sale, gain on sale of business and other unallocated corporate income and expenses. The following tables present information about the Company’s reportable segments, including corresponding amounts for the prior year. Post’s external revenues were primarily generated by sales within the United States; foreign (primarily located in the United Kingdom and Canada) sales were approximately 8% of total fiscal 2017 net sales. Sales are attributed to individual countries based on the address to which the product is shipped. As of September 30, 2017 and 2016 , the majority of Post’s tangible long-lived assets were located in the United States; the remainder are located primarily in the United Kingdom and Canada which combined have a net carrying value of approximately $311.1 and $39.5 , respectively. In the fiscal years ended September 30, 2017 , 2016 and 2015 , one customer accounted for $704.1 , $668.8 and $464.1 , respectively, or approximately 13% , 13% and 10% , of total net sales, respectively. All segments, except Weetabix, sell products to this major customer. 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” excludes additions through business acquisitions (see Note 5) and includes the non-monetary portion of asset exchanges. Year Ended September 30, 2017 2016 2015 Net Sales Post Consumer Brands $ 1,851.5 $ 1,838.5 $ 1,365.9 Michael Foods Group 2,116.2 2,184.7 2,305.7 Active Nutrition 713.2 574.7 555.0 Private Brands 432.5 429.1 421.7 Weetabix 112.4 — — Eliminations — (0.2 ) (0.1 ) Total $ 5,225.8 $ 5,026.8 $ 4,648.2 Segment Profit (Loss) Post Consumer Brands $ 359.0 $ 302.9 $ 219.5 Michael Foods Group 133.1 276.6 188.2 Active Nutrition 96.4 44.7 (13.8 ) Private Brands 31.5 28.0 27.5 Weetabix 14.5 — — Total segment profit 634.5 652.2 421.4 General corporate expenses and other 87.7 106.5 147.9 Impairment of goodwill and other intangibles 26.5 — 60.8 Interest expense, net 314.8 306.5 257.5 Loss on extinguishment of debt, net 222.9 86.4 30.0 Other (income) expense, net (91.8 ) 182.9 92.5 Earnings (loss) before income taxes $ 74.4 $ (30.1 ) $ (167.3 ) Net sales by product Cereal and granola $ 1,963.9 $ 1,838.5 $ 1,365.9 Egg and egg products 1,419.1 1,417.0 1,511.9 Cheese and dairy 259.4 320.9 340.4 Refrigerated potato 192.3 179.5 182.3 Pasta 249.4 270.6 275.0 Protein-based products and supplements 713.2 574.7 555.0 Nut butters and dried nut and fruit 432.5 429.1 421.7 Eliminations (4.0 ) (3.5 ) (4.0 ) Total $ 5,225.8 $ 5,026.8 $ 4,648.2 Additions to property and intangibles Post Consumer Brands $ 65.5 $ 39.2 $ 20.7 Michael Foods Group 76.3 58.3 60.5 Active Nutrition 3.9 4.4 7.2 Private Brands 11.1 12.4 5.1 Weetabix 13.6 — — Corporate 20.0 7.2 27.0 Total $ 190.4 $ 121.5 $ 120.5 Depreciation and amortization Post Consumer Brands $ 118.8 $ 111.7 $ 77.9 Michael Foods Group 147.5 141.2 142.3 Active Nutrition 25.3 25.0 26.9 Private Brands 20.1 18.9 18.2 Weetabix 7.7 — — Total segment depreciation and amortization 319.4 296.8 265.3 Corporate and accelerated depreciation 3.7 6.0 7.5 Total $ 323.1 $ 302.8 $ 272.8 September 30, 2017 2016 2015 Assets, end of year Post Consumer Brands $ 3,611.9 $ 3,558.2 $ 3,642.3 Michael Foods Group 3,572.2 3,498.1 3,506.0 Active Nutrition 581.3 624.8 645.4 Private Brands 487.3 484.7 482.3 Weetabix 2,048.9 — — Corporate 1,575.2 1,194.8 887.9 Total $ 11,876.8 $ 9,360.6 $ 9,163.9

Summary Quarterly Financial Inf

Summary Quarterly Financial Information	12 Months Ended
	Sep. 30, 2017
Quarterly Financial Information [Abstract]
Summary Quarterly Financial Information (Unaudited)	SUMMARY QUARTERLY FINANCIAL INFORMATION (UNAUDITED) First Second Third Fourth Quarter Quarter Quarter Quarter Fiscal 2017 Net sales $ 1,249.8 $ 1,255.4 $ 1,272.1 $ 1,448.5 Gross profit 379.2 364.1 393.7 437.1 Impairment of goodwill and other intangible assets — — — 26.5 Net earnings (loss) 97.6 (4.0 ) (59.5 ) 14.2 Net earnings (loss) available to common shareholders 94.2 (7.4 ) (62.9 ) 10.9 Basic earnings (loss) per share $ 1.36 $ (0.11 ) $ (0.93 ) $ 0.16 Diluted earnings (loss) per share $ 1.22 $ (0.11 ) $ (0.93 ) $ 0.16 Fiscal 2016 Net sales $ 1,248.8 $ 1,271.1 $ 1,246.1 $ 1,260.8 Gross profit 362.5 409.3 398.2 377.4 Net earnings (loss) 25.5 4.9 3.3 (37.0 ) Net earnings (loss) available to common shareholders 10.5 1.5 — (40.4 ) Basic earnings (loss) per share $ 0.16 $ 0.02 $ — $ (0.58 ) Diluted earnings (loss) per share $ 0.15 $ 0.02 $ — $ (0.58 )

Subsequent Events

Subsequent Events	12 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS On September 19, 2017, the Company announced that it had entered into a definitive agreement to acquire Bob Evans Farms, Inc. (“Bob Evans”), a producer of retail refrigerated potato, pasta and vegetable-based side dishes, pork sausage, and a variety of refrigerated and frozen convenience food items for $77.00 per share. Bob Evans also has a foodservice business which sells a range of products, including sausage, sausage gravy, breakfast sandwiches and side dishes. The acquisition is expected to close in Post’s second quarter of fiscal 2018.

Summary of Significant Accoun31

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Principles of combination	Principles of Consolidation — The consolidated financial statements include the operations of Post and its wholly-owned and majority-owned subsidiaries. All intercompany transactions have been eliminated.
Use of estimates and allocations	Use of Estimates and Allocations — The consolidated financial statements of the Company are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), which require certain elections as to accounting policy, estimates and assumptions that affect the reported amounts of assets, liabilities, the disclosure of contingent liabilities at the dates of the financial statements and the reported amount of net revenues and expenses during the reporting periods. Significant accounting policy elections, estimates and assumptions include, among others, pension and benefit plan assumptions, valuation assumptions of goodwill and other intangible assets, marketing programs, self insurance reserves and income taxes. Actual results could differ from those estimates.
Business combinations	Business Combinations — The Company uses the acquisition method in accounting for acquired businesses. Under the acquisition method, our financial statements reflect the operations of an acquired business starting from the completion of the acquisition. The assets acquired and liabilities assumed are recorded at their respective estimated fair values at the date of the acquisition. Any excess of the purchase price over the estimated fair values of the identifiable net assets acquired is recorded as goodwill.
Cash equivalents	Cash Equivalents — Cash equivalents include all highly liquid investments with original maturities of less than three months.
Restricted cash	Restricted Cash — Restricted cash includes items such as cash deposits which serve as collateral for certain commodity hedging contracts as well as the Company's high deductible workers’ compensation insurance program. In addition, restricted cash at September 30, 2016 included deposits with third party escrow agents in connection with an acquisition that was credited against the purchase price when the transaction closed.
Receivables	Receivables — Receivables are reported at net realizable value. This value includes appropriate allowances for doubtful accounts, cash discounts, and other amounts which the Company does not ultimately expect to collect. The Company determines its allowance for doubtful accounts based on historical losses as well as the economic status of, and its relationship with its customers, especially those identified as “at risk.” A receivable is considered past due if payments have not been received within the agreed upon invoice terms. Receivables are written off against the allowance when the customer files for bankruptcy protection or are otherwise deemed to be uncollectible based upon the Company’s evaluation of the customer’s solvency.
Inventories	Inventories — Inventories, other than flocks, are generally valued at the lower of average cost (determined on a first-in, first-out basis) or net realizable value. Reported amounts have been reduced by an allowance for obsolete product and packaging materials based on a review of inventories on hand compared to estimated future usage and sales. Flock inventory represents the cost of purchasing and raising chicken flocks to egg laying maturity. The costs included in our flock inventory include the costs of the chicks, the feed fed to the birds and the labor and overhead costs incurred to operate the pullet facilities until the birds are transferred into the laying facilities, at which time their cost is amortized to operations, as cost of goods sold, over their expected useful lives of one to two years.
Restructuring Expenses and Assets Held-for-sale	Restructuring Expenses and Assets Held for Sale — Restructuring charges principally consist of severance, accelerated stock compensation and other employee separation costs, accelerated depreciation and certain long-lived asset impairments. The Company recognizes restructuring obligations and liabilities for exit and disposal activities at fair value in the period the liability is incurred. Employee severance costs are expensed when they become probable and reasonably estimable under established severance plans. Depreciation expense related to assets that will be disposed of or idled as a part of the restructuring activity is accelerated through the expected date of the asset shut down. Assets are classified as held for sale if the Company has committed to a plan for selling the assets, is actively and reasonably marketing them, and sale is reasonably expected within one year. The carrying value of assets held for sale is included in “Prepaid expenses and other current assets” on the Consolidated Balance Sheets. See Note 4 for information about restructuring expenses and assets held for sale.
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 20 years for machinery and equipment; 1 to 40 years for buildings, building improvements and leasehold improvements; and 1 to 5 years for software. Total depreciation expense was $164.0 , $150.2 and $131.1 in fiscal 2017 , 2016 and 2015 , respectively. Any gains and losses incurred on the sale or disposal of assets are included in "Other operating expenses, net” in the Consolidated Statements of Operations. Repair and maintenance costs incurred in connection with on-going and planned major maintenance activities are accounted for under the direct expensing method.
Other intangible assets	Other Intangible Assets — Other intangible assets consist primarily of customer relationships and trademarks/brands acquired in business combinations and includes 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 goodwill. Trademarks with indefinite lives are reviewed for impairment during the fourth quarter of each fiscal year following the annual forecasting process, or more frequently if facts and circumstances indicate the trademark may be impaired. The trademark impairment tests require us to estimate the fair value of the trademark and compare it to its carrying value. The estimated fair value is determined using an income-based approach (the relief-from-royalty method), which requires significant assumptions for each brand, including estimates regarding future revenue growth, discount rates, and appropriate royalty rates. Assumptions are determined after consideration of several factors for each brand, including profit levels, research of external royalty rates by third party experts and the relative importance of each brand to the Company. Revenue growth assumptions are based on historical trends and management’s expectations for future growth by brand. The discount rate is based on a weighted-average cost of capital utilizing industry market data of similar companies. In addition, definite-lived assets and indefinite-lived intangible assets are reassessed as needed when information becomes available that is believed to negatively impact the fair market value of an asset. In general, an asset is deemed impaired and written down to its fair value if estimated related future cash flows are less than its carrying amount. See Note 6 for information about goodwill impairments. For the year ended September 30, 2017, the Company conducted an impairment review and concluded there was no impairment of other intangible assets as of September 30, 2017. At September 30, 2017, the fair value of the Honey Bunches of Oats brand exceeded its carrying value of $243.9 by 8% . For the year ended September 30, 2016, the Company conducted an impairment review and concluded there was no impairment of other intangible assets as of September 30, 2016. At September 30, 2016, the estimated fair values of all other intangible assets exceeded their carrying value by at least 36% . At September 30, 2015, Post recorded impairment losses in the Post Consumer Brands segment of $3.7 for the Grape-Nuts brand and $0.1 for the 100% Bran brand to record these trademarks at their estimated current fair values of $11.2 and zero , respectively. Due to repeated past impairments, continued weakness in the brand forecasts and a lack of sales growth from recent brand support efforts, as of October, 1 2015, the Grape-Nuts brand was converted to a definite-lived asset and assigned a 20 year useful life. These fair value measurements fell within Level 3 of the fair value hierarchy as described in Note 14. The trademark impairment losses are reported in “Impairment of goodwill and other intangible assets” on the Consolidated Statements of Operations.
Deferred compensation investments	Deferred Compensation Investments — The Company funds a portion of its deferred compensation liability by investing in certain mutual funds in the same amounts as selected by the participating employees. Because management’s intent is to invest in a manner that matches the deferral options chosen by the participants and those participants can elect to transfer amounts in or out of each of the designated deferral options at any time, these investments have been classified as trading assets and are stated at fair value in “Prepaid expenses and other current assets” and “Other Assets” (see Note 14). Both realized and unrealized gains and losses on these assets are included in “Selling, general and administrative expenses” and offset the related change in the deferred compensation liability.
Revenue	Revenue — Revenue is recognized when title of goods and risk of loss is transferred to the customer, as specified by the shipping terms. Net sales reflect gross sales, including amounts billed to customers for shipping and handling, less sales discounts and trade allowances (including promotional price buy downs and new item promotional funding). Customer trade allowances are generally computed as a percentage of gross sales. Products are generally sold with no right of return except in the case of goods which do not meet product specifications or are damaged, and related reserves are maintained based on return history. If additional rights of return are granted, revenue recognition is deferred. Estimated reductions to revenue for customer incentive offerings are based upon customer redemption history.
Cost of good sold	Cost of Goods Sold — Cost of goods sold includes, among other things, inbound and outbound freight costs 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 Statement of Operations.
Advertising	Advertising — Advertising costs are expensed as incurred except for costs of producing media advertising such as television commercials or magazine advertisements, which are deferred until the first time the advertising takes place.
Stock-based compensation	Stock-based Compensation — The Company recognizes the cost of employee services received in exchange for awards of equity instruments based on the grant-date fair value of equity awards and the fair market value at each quarterly reporting date for liability awards. That cost is recognized over the period during which an employee is required to provide service in exchange for the award — the requisite service period (usually the vesting period). See Note 18 for disclosures related to stock-based compensation.
Income tax (benefit) expense	Income Tax Expense (Benefit) — Income tax expense (benefit) is estimated based on income taxes in each jurisdiction and includes the effects of both current tax exposures and the temporary differences resulting from differing treatment of items for tax and financial reporting purposes. These temporary differences result in deferred tax assets and liabilities. A valuation allowance is established against the related deferred tax assets to the extent that it is not more likely than not that the future benefits will 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 due to an underpayment of income taxes is classified as income taxes. The Company considers the undistributed earnings of its foreign subsidiaries to be permanently reinvested, so no U.S. taxes have been provided in relation to the Company's investment in its foreign subsidiaries. See Note 8 for disclosures related to income taxes.

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Property	Property consisted of: September 30, 2017 2016 Land and land improvements $ 90.9 $ 58.0 Buildings and leasehold improvements 699.4 618.2 Machinery and equipment 1,439.3 1,094.5 Software 64.5 50.4 Construction in progress 100.0 79.2 2,394.1 1,900.3 Accumulated depreciation (703.4 ) (545.9 ) $ 1,690.7 $ 1,354.4
Other intangible assets	Other intangible assets consisted of: September 30, 2017 September 30, 2016 Carrying Amount Accum. Amort. Net Amount Carrying Amount Accum. Amort. Net Amount Subject to amortization: Customer relationships $ 2,249.3 $ (416.7 ) $ 1,832.6 $ 2,012.7 $ (302.0 ) $ 1,710.7 Trademarks/brands 834.1 (162.9 ) 671.2 795.1 (120.6 ) 674.5 Other 21.7 (9.8 ) 11.9 21.7 (7.7 ) 14.0 3,105.1 (589.4 ) 2,515.7 2,829.5 (430.3 ) 2,399.2 Not subject to amortization: Trademarks/brands 838.2 — 838.2 434.5 — 434.5 $ 3,943.3 $ (589.4 ) $ 3,353.9 $ 3,264.0 $ (430.3 ) $ 2,833.7

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Schedule of Restructuring and Related Costs [Table Text Block]	Amounts related to the restructuring events are shown in the following table. Costs are recognized in “Selling, general and administrative expenses” in the Consolidated Statements of Operations. These expenses are not included in the measure of segment performance for any segment (see Note 21). Employee-Related Costs Pension Curtailment Accelerated Depreciation Total Balance, September 30, 2014 $ 0.7 $ — $ — $ 0.7 Charge to expense 13.2 — 2.1 15.3 Cash payments (3.4 ) — — (3.4 ) Non-cash charges — — (2.1 ) (2.1 ) Balance, September 30, 2015 $ 10.5 $ — $ — $ 10.5 Charge to expense 2.1 — 0.4 2.5 Cash payments (10.6 ) — — (10.6 ) Non-cash charges (0.9 ) — (0.4 ) (1.3 ) Balance, September 30, 2016 $ 1.1 $ — $ — $ 1.1 Charge to expense — — — — Cash payments (1.1 ) — — (1.1 ) Non-cash charges — — — — Balance, September 30, 2017 $ — $ — $ — $ — Total expected restructuring charge $ 18.5 $ 1.7 $ 20.1 $ 40.3 Cumulative incurred to date 18.5 1.7 20.1 40.3 Remaining expected restructuring charge $ — $ — $ — $ —

Business Combinations and Div34

Business Combinations and Divestitures (Tables)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following table provides the allocation of the purchase price related to the fiscal 2017 acquisitions of NPE and the preliminary purchase price related to the acquisition of the Weetabix Group based upon the fair value of assets and liabilities assumed. Certain preliminary values of the Weetabix Group acquisition, including receivables, inventory, property, goodwill, other intangible assets, other assets, other current liabilities, deferred taxes and other liabilities, are not yet finalized pending the final purchase price allocation and are subject to change once additional information is obtained. Measurement period adjustments have been made to the allocation of purchase price for the acquisition of NPE since the date of acquisition related to working capital settlements, updated valuations of property and intangibles, income tax receivable and deferred taxes. The fair value of goodwill related to the acquisition of NPE will not be deductible for U.S. income tax purposes. The Company does not expect the final fair value of goodwill related to the acquisition of the Weetabix Group to be deductible for U.S. income tax purposes. NPE The Weetabix Group Cash and cash equivalents $ 5.6 $ 62.2 Receivables 8.5 39.7 Inventories 2.1 63.4 Prepaid expenses and other current assets 0.4 1.2 Property 10.4 283.9 Goodwill 46.3 969.3 Other intangible assets 51.4 608.4 Other assets — 112.0 Current portion of capital lease (0.1 ) — Accounts payable (6.3 ) (66.3 ) Other current liabilities (2.9 ) (28.4 ) Long-term capital lease (0.2 ) — Deferred tax liability - long-term (18.7 ) (137.6 ) Other liabilities — (10.9 ) Noncontrolling interest — (9.7 ) Total acquisition cost $ 96.5 $ 1,887.2	The following table provides the allocation of the purchase price related to the fiscal 2016 acquisition of WEF based upon the fair value of assets and liabilities assumed. The Company expects the final fair value of goodwill related to the acquisition of WEF to be deductible for U.S. income tax purposes. WEF Cash and cash equivalents $ 19.2 Receivables 11.1 Inventories 10.3 Prepaid expenses and other current assets 0.5 Property 56.2 Goodwill 4.2 Other intangible assets 15.2 Other assets 0.1 Accounts payable (2.2 ) Other current liabilities (1.0 ) Total acquisition cost $ 113.6	PowerBar ABC MOM Brands Cash and cash equivalents $ 2.4 $ 0.6 $ 11.1 Receivables 6.5 12.8 41.7 Inventories 23.1 15.5 97.9 Prepaid expenses and other current assets 0.1 0.4 6.2 Property 17.9 19.7 532.1 Goodwill 18.6 49.6 195.6 Other intangible assets 61.0 71.9 364.4 Deferred tax asset - non-current 11.7 — — Other assets — 0.4 — Accounts payable (1.2 ) (9.0 ) (33.0 ) Deferred tax liability - current (0.2 ) (0.4 ) (5.4 ) Other current liabilities (4.4 ) (2.8 ) (24.9 ) Deferred tax liability - non-current (1.1 ) (30.7 ) (6.9 ) Other liabilities — — (1.3 ) Total acquisition cost $ 134.4 $ 128.0 $ 1,177.5
Business Acquisition, Pro Forma Information [Table Text Block]	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 dates, nor is it necessarily an indication of future operating results. 2017 2016 2015 Pro forma net sales $ 5,614.9 $ 5,751.2 $ 5,236.6 Pro forma net earnings (loss) available to common shareholders $ 71.9 $ 2.0 $ (73.3 ) Pro forma basic earnings (loss) per share $ 1.06 $ 0.03 $ (1.29 ) Pro forma diluted earnings (loss) per share $ 1.03 $ 0.03 $ (1.29 )

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in carrying amount of goodwill	The changes in the carrying amount of goodwill by segment are noted in the following table. Post Consumer Brands Michael Foods Group Active Nutrition Private Brands Weetabix Total Balance, September 30, 2015 Goodwill (gross) $ 2,069.0 $ 1,341.6 $ 180.7 $ 178.9 $ — $ 3,770.2 Accumulated impairment losses (609.1 ) — (88.3 ) — — (697.4 ) Goodwill (net) $ 1,459.9 $ 1,341.6 $ 92.4 $ 178.9 $ — $ 3,072.8 Goodwill acquired — 4.2 — — — 4.2 Currency translation adjustment 0.1 — — 2.6 — 2.7 Balance, September 30, 2016 Goodwill (gross) $ 2,069.1 $ 1,345.8 $ 180.7 $ 181.5 $ — $ 3,777.1 Accumulated impairment losses (609.1 ) — (88.3 ) — — (697.4 ) Goodwill (net) $ 1,460.0 $ 1,345.8 $ 92.4 $ 181.5 $ — $ 3,079.7 Goodwill acquired 5.3 46.3 — — 964.0 1,015.6 Impairment loss — — (26.5 ) — — (26.5 ) Currency translation adjustment 0.3 — — — (37.1 ) (36.8 ) Balance, September 30, 2017 Goodwill (gross) $ 2,074.7 $ 1,392.1 $ 180.7 $ 181.5 $ 926.9 $ 4,755.9 Accumulated impairment losses (609.1 ) — (114.8 ) — — (723.9 ) Goodwill (net) $ 1,465.6 $ 1,392.1 $ 65.9 $ 181.5 $ 926.9 $ 4,032.0

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Reconciliation of provision (benefit) for income taxes	The benefit for income taxes consisted of the following: Year Ended September 30, 2017 2016 2015 Current: Federal $ (5.8 ) $ 37.6 $ 59.5 State 4.3 1.7 2.9 Foreign 10.2 8.5 5.7 8.7 47.8 68.1 Deferred: Federal 19.7 (64.8 ) (116.0 ) State 2.7 (7.5 ) (2.1 ) Foreign (5.0 ) (2.3 ) (2.0 ) 17.4 (74.6 ) (120.1 ) Income tax expense (benefit) $ 26.1 $ (26.8 ) $ (52.0 )
Reconciliation of income tax (benefit) provision	A reconciliation of income tax benefit with amounts computed at the statutory federal rate follows: Year Ended September 30, 2017 2016 2015 Computed tax at federal statutory rate (35%) $ 26.1 $ (10.5 ) $ (58.6 ) Non-deductible goodwill impairment loss 7.2 — 16.5 Non-deductible compensation 1.8 2.6 0.4 Non-deductible transaction costs 2.9 — 0.6 Domestic production activities deduction — (4.3 ) (5.9 ) State income taxes, net of effect on federal tax 0.8 (6.2 ) (7.2 ) Non-taxable interest income (3.4 ) (2.6 ) (2.7 ) Valuation allowances 4.8 3.8 6.7 Change in deferred tax rates — (2.0 ) 4.9 Uncertain tax positions (0.5 ) (2.0 ) (3.4 ) Sale and liquidation of Michael Foods Canadian egg business — (3.6 ) — Enacted tax law and changes — 0.7 (0.4 ) Income tax credits (1.4 ) (1.5 ) (0.4 ) Rate differential on foreign income (6.8 ) (1.8 ) (1.4 ) Excess tax benefits for share-based payments (6.2 ) — — Other, net (none in excess of 5% of statutory tax) 0.8 0.6 (1.1 ) Income tax expense (benefit) $ 26.1 $ (26.8 ) $ (52.0 )
Deferred tax assets (liabilities)	Deferred tax non-current assets (liabilities) were as follows: September 30, 2017 September 30, 2016 Assets Liabilities Net Assets Liabilities Net Accrued vacation, incentive and severance $ 16.2 $ — $ 16.2 $ 14.3 $ — $ 14.3 Inventory 3.0 — 3.0 2.5 — 2.5 Accrued liabilities 16.6 — 16.6 24.0 — 24.0 Property — (210.1 ) (210.1 ) — (172.3 ) (172.3 ) Intangible assets — (882.5 ) (882.5 ) — (784.3 ) (784.3 ) Pension and other postretirement benefits 5.3 — 5.3 31.7 — 31.7 Stock-based and deferred compensation 28.7 — 28.7 22.2 — 22.2 Derivative mark-to-market adjustments 91.9 — 91.9 121.6 — 121.6 Net operating loss carryforwards, credits 38.7 — 38.7 22.2 — 22.2 Other items 6.5 (1.6 ) 4.9 5.1 (1.3 ) 3.8 Total gross deferred income taxes 206.9 (1,094.2 ) (887.3 ) 243.6 (957.9 ) (714.3 ) Valuation allowance (18.5 ) — (18.5 ) (12.2 ) — (12.2 ) Total deferred taxes $ 188.4 $ (1,094.2 ) $ (905.8 ) $ 231.4 $ (957.9 ) $ (726.5 )
Income Tax Contingency [Line Items]
Summary of Income Tax Contingencies [Table Text Block]	Unrecognized tax benefits, September 30, 2015 $ 11.3 Additions for tax positions taken in current year and acquisitions 0.1 Reductions for tax positions taken in prior years (1.6 ) Settlements with tax authorities/statute expirations (0.5 ) Unrecognized tax benefits, September 30, 2016 $ 9.3 Additions for tax positions taken in current year and acquisitions — Reductions for tax positions taken in prior years — Settlements with tax authorities/statute expirations (0.7 ) Unrecognized tax benefits, September 30, 2017 $ 8.6

Earnings (loss) per Share (Tabl

Earnings (loss) per Share (Tables)	12 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Year ended September 30, 2017 2016 2015 Net earnings (loss) for basic loss per share $ 34.8 $ (28.4 ) $ (132.3 ) Net earnings (loss) for diluted loss per share $ 34.8 $ (28.4 ) $ (132.3 ) Weighted-average shares outstanding 65.2 63.9 51.8 Effect of TEUs on weighted-average shares for basic earnings (loss) per share 2.6 4.9 4.9 Weighted-average shares for basic earnings (loss) per share 67.8 68.8 56.7 Effect of dilutive securities: Stock options 1.8 — — Restricted stock awards 0.3 — — Total dilutive securities 2.1 — — Weighted-average shares for diluted earnings (loss) per share 69.9 68.8 56.7 Basic earnings (loss) per common share $ 0.51 $ (0.41 ) $ (2.33 ) Diluted earnings (loss) per common share $ 0.50 $ (0.41 ) $ (2.33 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	The following table details the securities that have been excluded from the calculation of weighted-average shares for diluted earnings (loss) per share as they were anti-dilutive. Year ended September 30, 2017 2016 2015 Stock options 0.3 4.3 4.2 Stock appreciation rights — 0.2 0.3 Restricted stock awards — 0.5 0.5 Preferred shares conversion to common 9.1 9.1 11.0

Supplemental Operations State38

Supplemental Operations Statement and Cash Flow Information (Tables)	12 Months Ended
	Sep. 30, 2017
Supplemental Operations Statement and Cash Flow Information [Abstract]
Supplemental Operations Statement and Cash Flow Information	Year Ended September 30, 2017 2016 2015 Advertising and promotion expenses $ 159.7 $ 184.2 $ 137.3 Repair and maintenance expenses 162.6 141.6 92.1 Research and development expenses 18.6 16.3 16.8 Rent expense 41.8 32.0 23.3 Interest income (6.8 ) (2.7 ) (0.8 ) Interest paid 333.6 309.6 235.5 Income taxes paid 29.6 73.4 46.4

Supplemental Balance Sheet In39

Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Sep. 30, 2017
Supplemental Balance Sheet Information [Abstract]
Supplemental Balance Sheet Information	September 30, 2017 2016 Receivables, net Trade $ 421.6 $ 354.9 Income tax receivable 46.4 23.6 Other 14.2 8.1 482.2 386.6 Allowance for doubtful accounts (1.6 ) (1.6 ) $ 480.6 $ 385.0 Inventories Raw materials and supplies $ 129.8 $ 112.4 Work in process 16.9 17.4 Finished products 395.6 339.3 Flocks 31.2 34.0 $ 573.5 $ 503.1 Other Assets Pension asset $ 154.6 $ — Other 29.7 15.9 $ 184.3 $ 15.9 Accounts Payable Trade $ 306.5 $ 228.8 Book cash overdrafts 17.8 26.6 Other 11.7 9.0 $ 336.0 $ 264.4 Other Current Liabilities Advertising and promotion $ 74.5 $ 95.8 Accrued interest 36.5 55.2 Accrued compensation 89.9 103.9 Hedging liabilities 54.6 5.5 Accrued legal settlements 8.6 37.3 Other 82.2 59.6 $ 346.3 $ 357.3 Other Liabilities Pension and other postretirement benefit obligations $ 83.5 $ 83.2 Hedging liabilities - non-current 188.9 313.2 Accrued compensation - non-current 29.2 22.7 Other 26.2 21.2 $ 327.8 $ 440.3

Allowance for Doubtful Accoun40

Allowance for Doubtful Accounts (Tables)	12 Months Ended
	Sep. 30, 2017
Allowance for Doubtful Accounts [Abstract]
Allowance for Doubtful Accounts	September 30, 2017 2016 2015 Balance, beginning of year $ 1.6 $ 2.0 $ 1.4 Provision charged to expense 0.3 1.2 0.7 Write-offs, less recoveries (0.3 ) (1.6 ) (0.3 ) Impact of acquisitions — — 0.2 Balance, end of year $ 1.6 $ 1.6 $ 2.0

Derivative Financial Instrume41

Derivative Financial Instruments and Hedging (Tables)	12 Months Ended
	Sep. 30, 2017
Derivative [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	September 30, September 30, Not designated as hedging instruments under ASC Topic 815: Commodity contracts $ 53.8 $ 49.8 Energy contracts 25.6 23.6 Foreign exchange contracts - Forward contracts 3.8 — Interest rate swap 76.1 77.6 Interest rate swaps - Rate-lock swaps 1,649.3 1,649.3 Designated as hedging instruments under ASC Topic 815: Foreign exchange contracts - Forward contracts 20.9 — Foreign exchange contracts - Cross-currency swaps 448.7 — Interest rate swap 1,000.0 —
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following tables present the balance sheet location and fair value of the Company’s derivative instruments on a gross and net basis as of September 30, 2017 and 2016 , along with the portion designated as hedging instruments under ASC Topic 815. The Company does not offset derivative assets and liabilities within the Consolidated Balance Sheets. Fair Value Portion Designated as Hedging Instruments Balance Sheet Location September 30, September 30, September 30, September 30, Asset Derivatives: Commodity contracts Prepaid expenses and other current assets $ 0.5 $ 0.6 $ — $ — Energy contracts Prepaid expenses and other current assets 3.8 2.4 — — Foreign exchange contracts Prepaid expenses and other current assets 1.3 — 1.1 — Foreign exchange contracts Other assets 0.3 — 0.3 — $ 5.9 $ 3.0 $ 1.4 $ — Liability Derivatives: Commodity contracts Other current liabilities $ 1.9 $ 3.3 $ — $ — Energy contracts Other current liabilities 0.3 0.2 — — Foreign exchange contracts Other current liabilities 1.5 — 1.5 — Foreign exchange contracts Other liabilities 23.6 — 23.6 — Interest rate swaps Other current liabilities 50.9 2.0 0.7 — Interest rate swaps Other liabilities 165.3 313.2 4.2 — $ 243.5 $ 318.7 $ 30.0 $ —
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following tables present the effects of the Company’s derivative instruments on the Company’s Consolidated Statements of Operations for the years ended September 30, 2017 , 2016 and 2015 and Consolidated Statements of Comprehensive Income (Loss) as of September 30, 2017 and 2016 . Derivatives Not Designated as Hedging Instruments Statement of Operations Location (Gain) Loss Recognized in Statement of Operations 2017 2016 2015 Commodity contracts Cost of goods sold $ (0.4 ) $ 7.5 $ (5.2 ) Energy contracts Cost of goods sold (1.3 ) 1.2 12.8 Foreign exchange contracts Selling, general and administrative expenses 0.8 — — Interest rate swaps Other (income) expense, net (102.1 ) 182.9 92.5 Derivatives Designated as Hedging Instruments (Gain) Loss Recognized in OCI Loss Reclassified from Accumulated OCI into Earnings Loss Recognized in Earnings [amount excluded from effectiveness testing] Statement of Operations Location 2017 2016 2017 2016 2017 2016 Foreign exchange contracts $ (1.6 ) $ — $ — $ — $ — $ — Selling, general and administrative expenses Interest rate swaps 5.6 — 0.7 — — — Interest expense, net Cross-currency swaps (a) 14.8 — — — 10.3 — Other expense (income), net (a) On July 3, 2017, the Company designated its cross-currency swaps, entered into in the third quarter of fiscal 2017, as net investment hedges. Prior to the designation, mark to market losses of $10.3 were recognized in “Other expense (income), net” in the Consolidated Statement of Operations.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value	The following table presents the assets and liabilities measured at fair value on a recurring basis and the basis for that measurement according to the levels in the fair value hierarchy in ASC Topic 820: September 30, 2017 September 30, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Assets Deferred compensation investment $ 15.4 $ 15.4 $ — $ 11.5 $ 11.5 $ — Derivative assets 5.9 — 5.9 3.0 — 3.0 $ 21.3 $ 15.4 $ 5.9 $ 14.5 $ 11.5 $ 3.0 Liabilities Deferred compensation liabilities $ 22.5 $ — $ 22.5 $ 17.3 $ — $ 17.3 Derivative liabilities 243.5 — 243.5 318.7 — 318.7 $ 266.0 $ — $ 266.0 $ 336.0 $ — $ 336.0
Fair Value Measurements, Nonrecurring	The following table summarizes the Level 3 activity. For additional information on assets held for sale, see Note 4. Balance, September 30, 2015 $ 11.4 Transfers into held for sale 9.6 Losses on assets held for sale (9.3 ) Proceeds from the sale of assets held for sale (1.6 ) Balance, September 30, 2016 $ 10.1 Gain on sale of assets held for sale 0.2 Proceeds from the sale of assets held for sale (10.3 ) Balance, September 30, 2017 $ —

Long Term Debt (Tables)

Long Term Debt (Tables)	12 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	September 30, 2017 2016 5.50% Senior Notes maturing March 2025 $ 1,000.0 $ — 5.75% Senior Notes maturing March 2027 1,500.0 — 5.00% Senior Notes maturing August 2026 1,750.0 1,750.0 7.75% Senior Notes maturing March 2024 — 800.0 8.00% Senior Notes maturing July 2025 137.5 400.0 6.00% Senior Notes maturing December 2022 630.0 630.0 6.75% Senior Notes maturing December 2021 — 875.0 7.375% Senior Notes maturing February 2022 — 133.0 Term Loan 2,194.5 — TEUs (see Note 19) — 11.0 4.57% 2012 Series Bond maturing September 2017 — 1.3 Capital leases 0.2 — 7,212.2 4,600.3 Less: Current Portion (22.1 ) (12.3 ) Debt issuance costs, net (81.8 ) (53.5 ) Plus: Unamortized premium 40.8 16.7 Total long-term debt $ 7,149.1 $ 4,551.2

Pension and Other Postretirem44

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Sep. 30, 2017
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
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, 2017 , and a statement of the funded status and amounts recognized on the combined balance sheets as of September 30, 2017 and 2016. North America Other International Year Ended Year Ended 2017 2016 2017 2016 Change in benefit obligation Benefit obligation at beginning of period $ 71.2 $ 58.1 $ — $ — Service cost 4.1 4.0 1.7 — Interest cost 2.5 2.5 4.9 — Plan participants’ contributions 0.6 0.6 0.6 — Plan amendment (a) — 0.5 — — Actuarial loss (gain) (1.0 ) 8.0 (46.4 ) — Business combinations 25.5 — 746.0 — Benefits paid (3.0 ) (2.7 ) (6.2 ) — Currency translation 0.7 0.2 23.0 — Benefit obligation at end of period $ 100.6 $ 71.2 $ 723.6 $ — Change in fair value of plan assets Fair value of plan assets at beginning of period $ 54.3 $ 44.4 $ — $ — Actual return on plan assets 5.4 5.5 0.3 — Employer contributions 7.7 6.3 2.4 — Business combinations 15.2 — 852.2 — Plan participants’ contributions 0.6 0.6 0.6 — Benefits paid (3.0 ) (2.7 ) (6.2 ) — Currency translation 0.7 0.2 27.4 — Fair value of plan assets at end of period 80.9 54.3 876.7 — Funded status $ (19.7 ) $ (16.9 ) $ 153.1 $ — Amounts recognized in assets or liabilities Other assets $ 1.5 $ — $ 153.1 $ — Other liabilities (21.2 ) (16.9 ) — — Net amount recognized $ (19.7 ) $ (16.9 ) $ 153.1 $ — Amounts recognized in accumulated other comprehensive loss Net actuarial loss $ 0.6 $ 19.1 $ (40.2 ) $ — Prior service cost (credit) 14.3 0.8 — — Total $ 14.9 $ 19.9 $ (40.2 ) $ — Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 3.86 % 3.66 % n/a n/a Discount rate — Canadian plans 3.63 % 3.18 % n/a n/a Discount rate — Other international plans n/a n/a 2.72 % n/a Rate of compensation increase — U.S. plans 3.00 % 3.00 % n/a n/a Rate of compensation increase — Canadian plans 2.69 % 2.75 % n/a n/a Rate of compensation increase — Other international plans n/a n/a 2.70 % n/a (a) In the second quarter of fiscal 2016, the Company finalized a new collective bargaining agreement that resulted in an amendment to its North American pension plans. The following table provides a reconciliation of the changes in the North American other postretirement benefit obligations over the two year period ended September 30, 2017 . Besides the North American plans, the Company does not maintain any other postretirement benefit plans. Year Ended 2017 2016 Change in benefit obligation Benefit obligation at beginning of period $ 68.6 $ 112.4 Service cost 0.6 1.0 Interest cost 2.0 4.0 Plan amendment (a) (0.1 ) (36.1 ) Actuarial gain (4.4 ) (11.3 ) Benefits paid (2.1 ) (1.6 ) Currency translation 0.4 0.2 Benefit obligation at end of period $ 65.0 $ 68.6 Change in fair value of plan assets Employer contributions 2.1 1.6 Benefits paid (2.1 ) (1.6 ) Fair value of plan assets at end of period — — Funded status $ (65.0 ) $ (68.6 ) Amounts recognized in assets or liabilities Other current liabilities (2.7 ) (2.3 ) Other liabilities (62.3 ) (66.3 ) Net amount recognized $ (65.0 ) $ (68.6 ) Amounts recognized in accumulated other comprehensive loss Net actuarial loss $ 8.6 $ 13.6 Prior service cost (credit) (28.8 ) (33.5 ) Total $ (20.2 ) $ (19.9 ) Weighted-average assumptions used to determine benefit obligation Discount rate — U.S. plans 3.77 % 3.54 % Discount rate — Canadian plans 3.69 % 3.23 % Rate of compensation increase — Canadian plans 2.75 % 2.75 % (a) In the second quarter of fiscal 2016, the Company finalized a new collective bargaining agreement that resulted in an amendment to its pension and other postretirement benefit plans.
Schedule of net benefit costs and assumptions used in calculation	The following tables provide the components of net periodic benefit cost for the pension plans including amounts recognized in OCI. North America Year Ended September 30, 2017 2016 2015 Components of net periodic benefit cost Service cost $ 4.1 $ 4.0 $ 3.8 Interest cost 2.5 2.5 2.2 Expected return on plan assets (3.2 ) (2.6 ) (2.4 ) Recognized net actuarial loss 1.6 1.1 0.9 Recognized prior service cost 0.2 0.3 0.3 Net periodic benefit cost $ 5.2 $ 5.3 $ 4.8 Weighted-average assumptions used to determine net benefit cost Discount rate — U.S. plans 3.66 % 4.55 % 4.56 % Discount rate — Canadian plans 3.18 % 3.82 % 4.25 % Rate of compensation increase — U.S. plans 2.99 % 3.00 % 3.00 % Rate of compensation increase — Canadian plans 2.50 % 2.75 % 2.75 % Expected return on plan assets — U.S. plans 5.33 % 5.20 % 5.72 % Expected return on plan assets — Canadian plans 6.00 % 6.00 % 6.00 % Changes in benefit obligation recognized in Total Comprehensive Income (Loss) Net (gain) loss $ (3.1 ) $ 5.1 $ 6.4 Recognized loss (1.6 ) (1.1 ) (0.9 ) Plan amendment — 0.5 — Recognized prior service cost (0.2 ) (0.3 ) (0.3 ) Currency translation (0.1 ) — — Total recognized in other comprehensive income or loss (before tax effects) $ (5.0 ) $ 4.2 $ 5.2 Other International Year Ended September 30, 2017 2016 2015 Components of net periodic benefit cost Service cost $ 1.7 $ — $ — Interest cost 4.9 — — Expected return on plan assets (7.5 ) — — Net periodic benefit cost $ (0.9 ) $ — $ — Weighted-average assumptions used to determine net benefit cost Discount rate 2.61 % — % — % Rate of compensation increase 2.75 % — % — % Expected return on plan assets 3.52 % — % — % Changes in plan assets and benefit obligation recognized in Total Comprehensive Income (Loss) Net (gain) loss $ (39.3 ) $ — $ — Currency translation (0.9 ) — — Total recognized in other comprehensive income or loss (before tax effects) $ (40.2 ) $ — $ —
Pension plan's assets measured at fair value on a recurring basis	The following tables present the North American and Other International pension plan’s assets measured at fair value on a recurring basis and the basis for that measurement. The fair value of mutual funds is based on quoted net asset values of the shares held by the plan at year end. North America September 30, 2017 September 30, 2016 Total Level 1 Level 2 Total Level 1 Level 2 Equities $ 16.4 $ 7.8 $ 8.6 $ 6.7 $ — $ 6.7 Bonds 11.3 11.3 — 6.0 6.0 — Fixed income 4.6 — 4.6 3.9 — 3.9 Real assets 0.9 0.9 — — — — Cash 0.8 0.8 — 0.6 0.6 — Fair value of plan assets in the fair value hierarchy 34.0 20.8 13.2 17.2 6.6 10.6 Equities 30.7 — — 20.3 — — Pooled assets 4.5 — — 4.3 — — Fixed income 9.6 — — 8.9 — — Real assets 2.1 — — 3.6 — — Investments measured at net asset value (a) 46.9 — — 37.1 — — Total plan assets $ 80.9 $ 20.8 $ 13.2 $ 54.3 $ 6.6 $ 10.6 Other International September 30, 2017 Total Level 1 Level 2 Bonds $ 461.7 $ 441.1 $ 20.6 Liability driven instruments 204.2 204.2 — Fixed income 108.3 108.3 — Cash 2.7 2.7 — Fair value of plan assets in the fair value hierarchy 776.9 756.3 20.6 Fixed income 95.0 — — Real assets 3.9 — — Other 0.9 — — Investments measured at net asset value (a) 99.8 — — Total plan assets $ 876.7 $ 756.3 $ 20.6
Change in accumulated postretirement benefit obligation from a 1% change in assumed health care cost trend	A 1% change in assumed health care cost trend rates would result in the following changes in the accumulated postretirement benefit obligation and in the total service and interest cost components for fiscal 2017 : Increase Decrease Effect on postretirement benefit obligation $ 6.7 $ (5.5 ) Effect on total service and interest cost 0.3 (0.2 )
Expected future benefit payments and related federal subsidy receipts	As of September 30, 2017 , expected future benefit payments and related federal subsidy receipts (Medicare Part D) in the next ten fiscal years were as follows: 2018 2019 2020 2021 2022 2023- 2027 Pension benefits $ 23.0 $ 24.2 $ 24.6 $ 25.5 $ 26.8 $ 153.3 Other benefits 2.7 3.0 3.2 3.3 3.5 18.2 Subsidy receipts — — 0.1 0.1 0.1 1.0

Stock-Based Compensation Plans

Stock-Based Compensation Plans Stock-Based Compensation Plans (Tables)	12 Months Ended
	Sep. 30, 2017
Share-based Payment Award [Line Items]
Stock Options, Activity [Table Text Block]	Stock Options Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2016 4,255,500 $ 42.15 Granted 343,000 71.32 Exercised (400,000 ) 33.51 Forfeited — — Expired — — Outstanding at September 30, 2017 4,198,500 45.36 6.29 $ 180.2 Vested and expected to vest as of September 30, 2017 4,198,500 45.36 6.29 180.2 Exercisable at September 30, 2017 3,060,163 41.00 5.76 144.7
Stock Options, Valuation Assumptions [Table Text Block]	2017 2016 2015 Expected term 6.5 6.5 5.3 Expected stock price volatility 30.6% 29.1% 27.9% Risk-free interest rate 1.9% 1.9% 1.6% Expected dividends 0% 0% 0% Fair value (per option) $24.80 $20.22 $7.22
Stock Settled
Share-based Payment Award [Line Items]
Stock Appreciation Rights, Activity [Table Text Block]	Stock-Settled Stock Appreciation Rights Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2016 152,831 $ 42.07 Granted — — Exercised (15,000 ) 46.19 Forfeited — — Expired — — Outstanding at September 30, 2017 137,831 41.63 5.69 $ 6.4 Vested and expected to vest as of September 30, 2017 137,831 41.63 5.69 6.4 Exercisable at September 30, 2017 102,831 38.17 5.08 5.2
Stock Appreciation Rights, Valuation Assumptions [Table Text Block]	2015 Expected term (in years) 6.5 Expected stock price volatility 29.2% Risk-free interest rate 1.6% Expected dividends 0% Fair value (per SSAR) $16.72
Restricted Stock Units, Activity [Table Text Block]	Restricted Stock Units Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2016 543,502 $ 54.11 Granted 342,778 73.79 Vested (136,557 ) 51.60 Forfeited (19,683 ) 63.84 Nonvested at September 30, 2017 730,040 63.55
Cash Settled
Share-based Payment Award [Line Items]
Stock Appreciation Rights, Activity [Table Text Block]	Cash-Settled Stock Appreciation Rights Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2016 105,000 $ 46.29 Granted — — Exercised (500 ) 18.10 Forfeited — — Expired — — Outstanding at September 30, 2017 104,500 46.43 7.40 $ 4.4 Vested and expected to vest as of September 30, 2017 104,500 46.43 7.40 4.4 Exercisable at September 30, 2017 71,166 45.83 7.31 3.0
Stock Appreciation Rights, Valuation Assumptions [Table Text Block]	2017 2016 2015 Expected term 2.9 3.8 4.8 Expected stock price volatility 31.7% 32.4% 29.7% Risk-free interest rate 1.6% 1.0% 1.3% Expected dividends 0% 0% 0% Fair value (per right) $54.18 $44.44 $29.10
Restricted Stock Units, Activity [Table Text Block]	Cash-Settled Restricted Stock Units Weighted- Average Grant Date Fair Value Per Share Nonvested at September 30, 2016 154,230 $ 47.66 Granted — — Vested (51,919 ) 44.41 Forfeited (2,192 ) 42.37 Nonvested at September 30, 2017 100,119 49.47

Tangible Equity Units (Tables)

Tangible Equity Units (Tables)	12 Months Ended
	Sep. 30, 2017
Tangible Equity Units [Abstract]
Tangible Equity Units Table	The aggregate values assigned upon issuance of each component of the TEUs were as follows (amounts in millions except price per TEU): Equity Component Debt Component TEUs Total Price per TEU $ 85.48 $ 14.52 $ 100.00 Gross proceeds $ 245.7 $ 41.8 $ 287.5 Issuance costs (7.6 ) (1.3 ) (8.9 ) Net proceeds $ 238.1 $ 40.5 $ 278.6 Balance sheet impact (at issuance) Long-term debt (deferred financing fees) $ — $ 1.3 $ 1.3 Current portion of long-term debt — 13.3 13.3 Long-term debt — 28.5 28.5 Additional paid-in capital 238.1 — 238.1

Segments (Tables)

Segments (Tables)	12 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	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” excludes additions through business acquisitions (see Note 5) and includes the non-monetary portion of asset exchanges. Year Ended September 30, 2017 2016 2015 Net Sales Post Consumer Brands $ 1,851.5 $ 1,838.5 $ 1,365.9 Michael Foods Group 2,116.2 2,184.7 2,305.7 Active Nutrition 713.2 574.7 555.0 Private Brands 432.5 429.1 421.7 Weetabix 112.4 — — Eliminations — (0.2 ) (0.1 ) Total $ 5,225.8 $ 5,026.8 $ 4,648.2 Segment Profit (Loss) Post Consumer Brands $ 359.0 $ 302.9 $ 219.5 Michael Foods Group 133.1 276.6 188.2 Active Nutrition 96.4 44.7 (13.8 ) Private Brands 31.5 28.0 27.5 Weetabix 14.5 — — Total segment profit 634.5 652.2 421.4 General corporate expenses and other 87.7 106.5 147.9 Impairment of goodwill and other intangibles 26.5 — 60.8 Interest expense, net 314.8 306.5 257.5 Loss on extinguishment of debt, net 222.9 86.4 30.0 Other (income) expense, net (91.8 ) 182.9 92.5 Earnings (loss) before income taxes $ 74.4 $ (30.1 ) $ (167.3 ) Net sales by product Cereal and granola $ 1,963.9 $ 1,838.5 $ 1,365.9 Egg and egg products 1,419.1 1,417.0 1,511.9 Cheese and dairy 259.4 320.9 340.4 Refrigerated potato 192.3 179.5 182.3 Pasta 249.4 270.6 275.0 Protein-based products and supplements 713.2 574.7 555.0 Nut butters and dried nut and fruit 432.5 429.1 421.7 Eliminations (4.0 ) (3.5 ) (4.0 ) Total $ 5,225.8 $ 5,026.8 $ 4,648.2 Additions to property and intangibles Post Consumer Brands $ 65.5 $ 39.2 $ 20.7 Michael Foods Group 76.3 58.3 60.5 Active Nutrition 3.9 4.4 7.2 Private Brands 11.1 12.4 5.1 Weetabix 13.6 — — Corporate 20.0 7.2 27.0 Total $ 190.4 $ 121.5 $ 120.5 Depreciation and amortization Post Consumer Brands $ 118.8 $ 111.7 $ 77.9 Michael Foods Group 147.5 141.2 142.3 Active Nutrition 25.3 25.0 26.9 Private Brands 20.1 18.9 18.2 Weetabix 7.7 — — Total segment depreciation and amortization 319.4 296.8 265.3 Corporate and accelerated depreciation 3.7 6.0 7.5 Total $ 323.1 $ 302.8 $ 272.8 September 30, 2017 2016 2015 Assets, end of year Post Consumer Brands $ 3,611.9 $ 3,558.2 $ 3,642.3 Michael Foods Group 3,572.2 3,498.1 3,506.0 Active Nutrition 581.3 624.8 645.4 Private Brands 487.3 484.7 482.3 Weetabix 2,048.9 — — Corporate 1,575.2 1,194.8 887.9 Total $ 11,876.8 $ 9,360.6 $ 9,163.9

Summary Quarterly Financial I48

Summary Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Sep. 30, 2017
Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information	First Second Third Fourth Quarter Quarter Quarter Quarter Fiscal 2017 Net sales $ 1,249.8 $ 1,255.4 $ 1,272.1 $ 1,448.5 Gross profit 379.2 364.1 393.7 437.1 Impairment of goodwill and other intangible assets — — — 26.5 Net earnings (loss) 97.6 (4.0 ) (59.5 ) 14.2 Net earnings (loss) available to common shareholders 94.2 (7.4 ) (62.9 ) 10.9 Basic earnings (loss) per share $ 1.36 $ (0.11 ) $ (0.93 ) $ 0.16 Diluted earnings (loss) per share $ 1.22 $ (0.11 ) $ (0.93 ) $ 0.16 Fiscal 2016 Net sales $ 1,248.8 $ 1,271.1 $ 1,246.1 $ 1,260.8 Gross profit 362.5 409.3 398.2 377.4 Net earnings (loss) 25.5 4.9 3.3 (37.0 ) Net earnings (loss) available to common shareholders 10.5 1.5 — (40.4 ) Basic earnings (loss) per share $ 0.16 $ 0.02 $ — $ (0.58 ) Diluted earnings (loss) per share $ 0.15 $ 0.02 $ — $ (0.58 )

Summary of Significant Accoun49

Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	2 Months Ended
	Sep. 30, 2017USD ($)
Weetabix Group
Business Acquisition
Receivables Sold	$ 37.3

Summary of Significant Accoun50

Summary of Significant Accounting Policies - Property (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Property, plant and equipment
Additions to property	$ 190.4	$ 121.5	$ 107.9
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	2,394.1	1,900.3
Accumulated depreciation	(703.4)	(545.9)
Property, net	1,690.7	1,354.4
Depreciation	164	150.2	$ 131.1
Land
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	90.9	58
Building and leasehold improvements
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 699.4	618.2
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	40 years
Machinery and equipment
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 1,439.3	1,094.5
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	20 years
Software
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 64.5	50.4
Software | Minimum
Property, Plant and Equipment, Net [Abstract]
Useful life	1 year
Software | Maximum
Property, Plant and Equipment, Net [Abstract]
Useful life	5 years
Construction in Progress
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, gross	$ 100	$ 79.2

Summary of Significant Accoun51

Summary of Significant Accounting Policies - Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Finite-Lived and Indefinite-Lived, Intangible Assets
Amortization of intangible assets	$ 159.1	$ 152.6	$ 141.7
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2,017	167.5
2,018	166.6
2,019	166.5
2,020	166.5
2,021	163.8
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	3,105.1	2,829.5
Finite-Lived Intangible Assets, Accumulated Amortization	(589.4)	(430.3)
Finite-Lived Intangible Assets, Net	2,515.7	2,399.2
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Carrying amount, total	3,943.3	3,264
Other intangible assets, net	3,353.9	2,833.7
Customer Relationships
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	2,249.3	2,012.7
Finite-Lived Intangible Assets, Accumulated Amortization	(416.7)	(302)
Finite-Lived Intangible Assets, Net	1,832.6	1,710.7
Trademarks
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	834.1	795.1
Finite-Lived Intangible Assets, Accumulated Amortization	(162.9)	(120.6)
Finite-Lived Intangible Assets, Net	671.2	674.5
Other Intangible Assets
Finite-Lived Intangible Assets [Abstract]
Finite-Lived Intangible Assets, Gross	21.7	21.7
Finite-Lived Intangible Assets, Accumulated Amortization	(9.8)	(7.7)
Finite-Lived Intangible Assets, Net	11.9	14
Trademarks
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 838.2	$ 434.5

Summary of Significant Accoun52

Summary of Significant Accounting Policies - Recoverability of Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2015	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount			36.00%
Trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	$ 838.2		$ 434.5
Post Grape Nuts [Member] | Trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Impairment Losses		$ 3.7
Indefinite-Lived Intangible Assets (Excluding Goodwill)		11.2
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
100% Bran [Member] | Trademarks
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Impairment Losses		0.1
Indefinite-Lived Intangible Assets (Excluding Goodwill)		$ 0
Honey Bunches of Oats [Member]
Finite-Lived Intangible Assets [Line Items]
Reporting Unit, Amount of Fair Value in Excess of Carrying Amount	$ 243.9
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	8.00%

Summary of Significant Accoun53

Summary of Significant Accounting Policies - Cost of Products Sold (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Accounting Policies [Abstract]
Cost Of Goods Sold, Storage And Warehouse Costs	$ 142.9	$ 124.1	$ 103.4

Summary of Significant Accoun54

Summary of Significant Accounting Policies Advertising (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Prepaid Advertising	$ 1.3	$ 1.6

Recently Issued and Adopted A55

Recently Issued and Adopted Accounting Standards Recently Issued and Adopted Accounting Standards (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
New Accounting Pronouncement, Early Adoption [Line Items]
Impairment of goodwill and other intangible assets	$ 26.5	$ 0	$ 0	$ 0	$ 26.5	$ 0	$ 60.8
Net Cash Provided by (Used in) Financing Activities					(2,053.1)	4.5	(1,372.4)
Net Cash (Used in) Provided by Operating Activities					386.7	502.4	451.6
Accounting Standards Update 2016-09
New Accounting Pronouncement, Early Adoption [Line Items]
Net Cash Provided by (Used in) Financing Activities					6.2	9.6	3.3
Net Cash (Used in) Provided by Operating Activities					6.2	$ 9.6	$ 3.3
Adjustments for New Accounting Principle, Early Adoption | Accounting Standards Update 2017-04
New Accounting Pronouncement, Early Adoption [Line Items]
Impairment of goodwill and other intangible assets					$ 26.5

Restructuring (Details)

Restructuring (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Restructuring Reserve [Roll Forward]
Balance	$ 1.1	$ 10.5	$ 0.7
Charge to expense	0	2.5	15.3
Cash payments	(1.1)	(10.6)	(3.4)
Non-cash charges	0	(1.3)	(2.1)
Balance	0	1.1	10.5
Total expected restructuring charge	40.3
Cumulative incurred to date	40.3
Remaining expected restructuring charge	0
Assets held for sale	(0.2)	9.3	34.2
Employee Severance
Restructuring Reserve [Roll Forward]
Balance	1.1	10.5	0.7
Charge to expense	0	2.1	13.2
Cash payments	(1.1)	(10.6)	(3.4)
Non-cash charges	0	(0.9)	0
Balance	0	1.1	10.5
Total expected restructuring charge	18.5
Cumulative incurred to date	18.5
Remaining expected restructuring charge	0
Pension Curtailment
Restructuring Reserve [Roll Forward]
Balance	0	0	0
Charge to expense	0	0	0
Cash payments	0	0	0
Non-cash charges	0	0	0
Balance	0	0	0
Total expected restructuring charge	1.7
Cumulative incurred to date	1.7
Remaining expected restructuring charge	0
Accelerated depreciation
Restructuring Reserve [Roll Forward]
Balance	0	0	0
Charge to expense	0	0.4	2.1
Cash payments	0	0	0
Non-cash charges	0	(0.4)	(2.1)
Balance	0	0	0
Total expected restructuring charge	20.1
Cumulative incurred to date	20.1
Remaining expected restructuring charge	0
Level 3
Restructuring Reserve [Roll Forward]
Fair value of assets held-for-sale	$ 0	10.1	$ 11.4
Assets held for sale		9.3
Modesto, California Facility | Prepaid expenses and other current assets | Level 3 | Facility Closing
Restructuring Reserve [Roll Forward]
Fair value of assets held-for-sale		4.3
Farmers Branch, Texas Facility | Prepaid expenses and other current assets | Level 3 | Facility Closing
Restructuring Reserve [Roll Forward]
Fair value of assets held-for-sale		$ 5.8

Business Combinations and Div57

Business Combinations and Divestitures (Details) $ / shares in Units, shares in Thousands, £ in Millions, $ in Millions	Jul. 03, 2017USD ($)	Jul. 03, 2017GBP (£)	Oct. 03, 2016USD ($)	Mar. 02, 2016USD ($)	Oct. 04, 2015USD ($)	May 04, 2015USD ($)$ / sharesshares	Nov. 01, 2014USD ($)	Oct. 02, 2014USD ($)	Feb. 28, 2017USD ($)	May 31, 2016USD ($)	Sep. 30, 2017USD ($)$ / sharesshares	Sep. 30, 2016USD ($)$ / sharesshares	Sep. 30, 2015USD ($)$ / shares	Sep. 30, 2017GBP (£)shares	Oct. 03, 2015USD ($)	Oct. 01, 2014USD ($)
Business Acquisition
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax											$ 0	$ 1.3	$ 0
Assets held for sale											(0.2)	9.3	34.2
Business Combination, Acquisition Related Costs											$ 30.5	$ 8.5	14.1
Common Stock, Shares, Issued | shares						2,450					66,100	64,900		66,100
Proceeds from sale of businesses											$ 0	$ 7.3	3.8
Goodwill											4,032	3,079.7
Payments to Acquire Businesses, Net of Cash Acquired											1,915.2	94.4	1,239.2
Pro forma net sales											5,614.9	5,751.2	5,236.6
Pro forma net earnings available to common stockholders											$ 71.9	$ 2	$ (73.3)
Pro forma basic earnings per share | $ / shares											$ 1.06	$ 0.03	$ (1.29)
Pro forma diluted earnings per share | $ / shares											$ 1.03	$ 0.03	$ (1.29)
National Pasteurized Eggs
Business Acquisition
Net Working Capital Settlement									$ 1.2
Business Combination, Purchase Price Adjustment, Income Tax Receivable Due Back to Seller											$ 0.7
Consideration Transferred			$ 93.5
Cash and cash equivalents											5.6
Receivables											8.5
Inventories											2.1
Prepaid expenses and other current assets											0.4
Property											10.4
Goodwill											46.3
Other intangible assets											51.4
Other assets											0
Current portion of capital lease											(0.1)
Accounts payable											(6.3)
Other current liabilities											(2.9)
Long-term capital lease											(0.2)
Deferred tax liability, long-term											(18.7)
Other liabilities											0
Total acquisition cost											96.5
Payments to Acquire Businesses, Net of Cash Acquired			$ 97
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value											0
National Pasteurized Eggs | Customer Relationships
Business Acquisition
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			16 years
Other intangible assets			$ 43.9
National Pasteurized Eggs | Trademarks
Business Acquisition
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			20 years
Other intangible assets			$ 7.5
Weetabix Group
Business Acquisition
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual											112.4
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual											14.5
Cash and cash equivalents											62.2
Receivables											39.7
Inventories											63.4
Prepaid expenses and other current assets											1.2
Property											283.9
Goodwill											969.3
Other intangible assets											608.4
Other assets											112
Current portion of capital lease											0
Accounts payable											(66.3)
Other current liabilities											(28.4)
Long-term capital lease											0
Deferred tax liability, long-term											(137.6)
Other liabilities											(10.9)
Total acquisition cost											1,887.2			£ 1,400
Payments to Acquire Businesses, Net of Cash Acquired	$ 1,454.1
Cash Acquired from Acquisition	$ 62.2	£ 48
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value											(9.7)
Weetabix Group | Customer Relationships
Business Acquisition
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years	20 years
Other intangible assets	$ 172.8
Weetabix Group | Trademarks
Business Acquisition
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	16 years	16 years
Other intangible assets	$ 30.5
Willamette Egg
Business Acquisition
Net Working Capital Settlement											4.6
Payments to Acquire Businesses, Gross					$ 90
Consideration Transferred					109
Cash and cash equivalents															$ 19.2
Receivables															11.1
Inventories															10.3
Prepaid expenses and other current assets															0.5
Property															56.2
Goodwill															4.2
Other intangible assets															15.2
Other assets															0.1
Accounts payable															(2.2)
Other current liabilities															(1)
Total acquisition cost															$ 113.6
Willamette Egg | Customer Relationships
Business Acquisition
Finite-lived Intangible Assets Acquired					$ 12.7
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					20 years
Willamette Egg | Trademarks
Business Acquisition
Finite-lived Intangible Assets Acquired					$ 2.5
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					20 years
Michael Foods Canada
Business Acquisition
Gain (Loss) on Disposition of Business											2
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax											1.3
Proceeds from Divestiture of Businesses				$ 6.9
Proceeds from Divestiture of Businesses, Net of Cash Divested				$ 6.4
Business Divestiture, Purchase Price Adjustment, Net Working Capital Settlement										$ 0.5
PowerBar and Musashi
Business Acquisition
Net Working Capital Settlement												$ 1.7
Assets held for sale													$ 3.7
Payments to Acquire Businesses, Gross								$ 150
Consideration Transferred								136.1
Proceeds from sale of businesses												3.8
Cash and cash equivalents																$ 2.4
Receivables																6.5
Inventories																23.1
Prepaid expenses and other current assets																0.1
Property																17.9
Goodwill																18.6
Other intangible assets																61
Deferred tax asset, long-term																11.7
Other assets																0
Accounts payable																(1.2)
Deferred tax liability, current																(0.2)
Other current liabilities																(4.4)
Deferred tax liability, long-term																(1.1)
Other liabilities																0
Total acquisition cost																$ 134.4
PowerBar and Musashi | Customer Relationships
Business Acquisition
Finite-lived Intangible Assets Acquired								$ 21
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								18 years 4 months
PowerBar and Musashi | Trademarks
Business Acquisition
Finite-lived Intangible Assets Acquired								$ 40
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life								20 years
PowerBar Australia
Business Acquisition
Business Divestiture, Purchase Price Adjustment, Net Working Capital Settlement											0.4
American Blanching Company
Business Acquisition
Payments to Acquire Businesses, Gross							$ 128
Cash and cash equivalents							0.6
Receivables							12.8
Inventories							15.5
Prepaid expenses and other current assets							0.4
Property							19.7
Goodwill							49.6
Other intangible assets							71.9
Deferred tax asset, long-term							0
Other assets							0.4
Accounts payable							(9)
Deferred tax liability, current							(0.4)
Other current liabilities							(2.8)
Deferred tax liability, long-term							(30.7)
Other liabilities							0
Total acquisition cost							128
American Blanching Company | Customer Relationships
Business Acquisition
Finite-lived Intangible Assets Acquired							$ 63.9
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							17 years
American Blanching Company | Trademarks
Business Acquisition
Finite-lived Intangible Assets Acquired							$ 8
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life							10 years
MOM Brands Company
Business Acquisition
Net Working Capital Settlement												$ 4
Shares Issued, Price Per Share | $ / shares						$ 46.60
Consideration Transferred, Other						$ 114.4
Consideration Transferred						1,181.5
Cash and cash equivalents						11.1
Receivables						41.7
Inventories						97.9
Prepaid expenses and other current assets						6.2
Property						532.1
Goodwill						195.6
Other intangible assets						364.4
Deferred tax asset, long-term						0
Other assets						0
Accounts payable						(33)
Deferred tax liability, current						(5.4)
Other current liabilities						(24.9)
Deferred tax liability, long-term						(6.9)
Other liabilities						(1.3)
Total acquisition cost						1,177.5
MOM Brands Company | Customer Relationships
Business Acquisition
Finite-lived Intangible Assets Acquired						$ 185.6
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						20 years
MOM Brands Company | Trademarks
Business Acquisition
Finite-lived Intangible Assets Acquired						$ 178.8
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						20 years
Selling, general and administrative expenses | Weetabix Group
Business Acquisition
Gain (Loss) on Foreign Currency Derivatives Recorded in Earnings, Net											30
Trademarks | Weetabix Group
Business Acquisition
Other intangible assets	$ 391
North America | Weetabix Group
Business Acquisition
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual											28.1
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual											$ (6.4)
North America | Weetabix Group | Customer Relationships
Business Acquisition
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	21 years	21 years
Other intangible assets	$ 14.1

Goodwill (Details)

Goodwill (Details) - USD ($)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Goodwill [Line Items]
Goodwill	$ 4,032,000,000	$ 3,079,700,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		36.00%
Impairment Loss		$ 0	$ (57,000,000)
Operating Segments
Goodwill [Line Items]
Goodwill (gross)	4,755,900,000	3,777,100,000	3,770,200,000
Accumulated impairment losses	(723,900,000)	(697,400,000)	(697,400,000)
Goodwill	4,032,000,000	3,079,700,000	3,072,800,000
Goodwill acquired	1,015,600,000	4,200,000
Impairment Loss	(26,500,000)
Currency translation adjustment	(36,800,000)	2,700,000
Operating Segments | Post Consumer Brands Segment
Goodwill [Line Items]
Goodwill (gross)	2,074,700,000	2,069,100,000	2,069,000,000
Accumulated impairment losses	(609,100,000)	(609,100,000)	(609,100,000)
Goodwill	1,465,600,000	1,460,000,000	1,459,900,000
Goodwill acquired	5,300,000	0
Impairment Loss	0
Currency translation adjustment	300,000	100,000
Operating Segments | Michael Foods Group Segment
Goodwill [Line Items]
Goodwill (gross)	1,392,100,000	1,345,800,000	1,341,600,000
Accumulated impairment losses	0	0	0
Goodwill	1,392,100,000	1,345,800,000	1,341,600,000
Goodwill acquired	46,300,000	4,200,000
Impairment Loss	0
Currency translation adjustment	0	0
Operating Segments | Active Nutrition Segment
Goodwill [Line Items]
Goodwill (gross)	180,700,000	180,700,000	180,700,000
Accumulated impairment losses	(114,800,000)	(88,300,000)	(88,300,000)
Goodwill	65,900,000	92,400,000	92,400,000
Goodwill acquired	0	0
Impairment Loss	(26,500,000)
Reporting Unit, Amount of Carrying Value in Excess of Fair Value	76.6
Currency translation adjustment	0	0
Operating Segments | Private Brands Segment
Goodwill [Line Items]
Goodwill (gross)	181,500,000	181,500,000	178,900,000
Accumulated impairment losses	0	0	0
Goodwill	181,500,000	181,500,000	178,900,000
Goodwill acquired	0	0
Impairment Loss	0
Currency translation adjustment	0	2,600,000
Operating Segments | Weetabix Group
Goodwill [Line Items]
Goodwill (gross)	926,900,000	0	0
Accumulated impairment losses	0	0	0
Goodwill	926,900,000	0	$ 0
Goodwill acquired	964,000,000	0
Impairment Loss	0
Currency translation adjustment	$ (37,100,000)	0
Operating Segments | Dymatize
Goodwill [Line Items]
Reporting Unit, Amount of Fair Value in Excess of Carrying Amount		$ 36,000,000
Operating Segments | All reporting units excluding Dymatize
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		33.00%
Operating Segments | All Reporting Units, Excluding Weetabix
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount	25.00%

Equity Interests (Details)

Equity Interests (Details) $ in Millions	Jul. 03, 2017joint_venture	Sep. 30, 2017USD ($)
Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Weetabix East Africa Limited
Schedule of Equity Method Investments [Line Items]
Ownership Percentage by Parent		50.10%
Weetabix Group
Schedule of Equity Method Investments [Line Items]
Number of Joint Ventures Acquired | joint_venture	2
Other Assets | Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Investment in subsidiaries		$ 4.5
Other Liabilities | Weetabix East Africa Limited
Schedule of Equity Method Investments [Line Items]
Accounts Payable, Related Parties		0.5
Other Operating Expense, Net | Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Loss from Equity Method Investments		0.1
Melck Street Management Proprietary Limited | Other Assets | Alpen Food Company South Africa (Proprietary) Limited
Schedule of Equity Method Investments [Line Items]
Accounts Receivable, Related Parties		$ 1
Pioneer Food Group Limited | Weetabix East Africa Limited
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		49.90%

Income Taxes - Income tax (bene

Income Taxes - Income tax (benefit) provision (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Current
Federal	$ (5.8)	$ 37.6	$ 59.5
State	4.3	1.7	2.9
Foreign	10.2	8.5	5.7
Current	8.7	47.8	68.1
Deferred
Federal	19.7	(64.8)	(116)
State	2.7	(7.5)	(2.1)
Foreign	(5)	(2.3)	(2)
Deferred	17.4	(74.6)	(120.1)
Income tax expense (benefit)	$ 26.1	$ (26.8)	$ (52)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed tax at federal statutory rate (35%)	$ 26.1	$ (10.5)	$ (58.6)
Non-deductible goodwill impairment loss	7.2	0	16.5
Non-deductible compensation	1.8	2.6	0.4
Non-deductible transaction costs	2.9	0	0.6
Domestic production activities deduction	0	(4.3)	(5.9)
State income taxes, net of effect on federal tax	0.8	(6.2)	(7.2)
Non-taxable interest income	(3.4)	(2.6)	(2.7)
Valuation allowances	4.8	3.8	6.7
Change in deferred tax rates	0	(2)	4.9
Uncertain tax positions	(0.5)	(2)	(3.4)
Sale and liquidation of Michael Foods Canadian egg business	0	(3.6)	0
Enacted tax law and changes	0	0.7	(0.4)
Income tax credits	(1.4)	(1.5)	(0.4)
Rate differential on foreign income	(6.8)	(1.8)	(1.4)
Tax effect of recently adopted accounting standards	(6.2)	0	0
Other, net (none in excess of 5% of statutory tax)	0.8	0.6	(1.1)
Income tax expense (benefit)	$ 26.1	$ (26.8)	$ (52)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
None in excess of 5% of computed tax	5.00%	5.00%	5.00%

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Components of Deferred Tax Assets [Abstract]
Net Income (Loss) Available to Common Stockholders, Diluted	$ 34.8	$ (28.4)	$ (132.3)
Components of Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liabilities	(905.8)	(726.5)
Assets
Components of Deferred Tax Assets [Abstract]
Total gross deferred income taxes, current	188.4	231.4
Assets | Noncurrent
Components of Deferred Tax Assets [Abstract]
Accrued vacation, incentive and severance	16.2	14.3
Inventory	3	2.5
Accrued liabilities	16.6	24
Pension and other postretirement benefits	5.3	31.7
Stock-based and deferred compensation	28.7	22.2
Derivative mark-to-market adjustments	91.9	121.6
Net operating loss carryforwards, credits	38.7	22.2
Other items, non-current assets	6.5	5.1
Valuation allowance	(18.5)	(12.2)
Total gross deferred income taxes	206.9	243.6
Liability
Components of Deferred Tax Liabilities [Abstract]
Total deferred tax liabilities, gross	(1,094.2)	(957.9)
Liability | Noncurrent
Components of Deferred Tax Assets [Abstract]
Property	(210.1)	(172.3)
Intangible assets	(882.5)	(784.3)
Components of Deferred Tax Liabilities [Abstract]
Other items, current liabilities	(1.6)	(1.3)
Noncurrent deferred tax liabilities	(1,094.2)	(957.9)
Net Assets
Deferred Tax Assets (Liabilities), Net [Abstract]
Total deferred tax assets (liabilities), net	905.8	726.5
Net Assets | Noncurrent
Components of Deferred Tax Assets [Abstract]
Accrued vacation, incentive and severance	16.2	14.3
Inventory	3	2.5
Accrued liabilities	16.6	24
Property	(210.1)	(172.3)
Intangible assets	(882.5)	(784.3)
Pension and other postretirement benefits	5.3	31.7
Stock-based and deferred compensation	28.7	22.2
Derivative mark-to-market adjustments	91.9	121.6
Net operating loss carryforwards, credits	38.7	22.2
Valuation allowance	(18.5)	(12.2)
Components of Deferred Tax Liabilities [Abstract]
Noncurrent deferred tax liabilities	(887.3)	(714.3)
Deferred Tax Assets (Liabilities), Net [Abstract]
Other items, net	$ 4.9	$ 3.8

Income Taxes - Income Taxes Nar

Income Taxes - Income Taxes Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosures
Effective tax rate	35.10%	89.00%	31.10%
Operating Loss Carryforwards, Limitations on Usage	$ 11.8
Undistributed Earnings of Foreign Subsidiaries	56.4
Foreign income (loss) before income taxes	24.7	$ 29.6	$ 7
Domestic Tax Authority
Income Tax Disclosures
Operating Loss Carryforwards	96.8
State and Local Jurisdiction
Income Tax Disclosures
Operating Loss Carryforwards	360.2
Foreign Tax Authority
Income Tax Disclosures
Operating Loss Carryforwards	$ 9.3
Minimum
Income Tax Disclosures
Tax Credit Carryforward, Expiration Date	Jan. 1, 2021
Minimum | State and Local Jurisdiction
Income Tax Disclosures
Tax Credit Carryforward, Expiration Date	Jan. 1, 2018
Maximum
Income Tax Disclosures
Tax Credit Carryforward, Expiration Date	Jan. 1, 2037
Maximum | State and Local Jurisdiction
Income Tax Disclosures
Tax Credit Carryforward, Expiration Date	Jan. 1, 2037

Unrecognized tax benefits (Deta

Unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 8.6	$ 9.3	$ 11.3
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	0	0.1
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	0	(1.6)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(0.7)	(0.5)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	5.6
Decrease in Unrecognized Tax Benefits is Reasonably Possible	1
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	2.7	2.4
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 0.3	$ (0.1)	$ 0

Earnings (loss) per Share (Deta

Earnings (loss) per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share, Diluted
Net Earnings (Loss) Available to Common Shareholders	$ 10.9	$ (62.9)	$ (7.4)	$ 94.2	$ (40.4)	$ 0	$ 1.5	$ 10.5	$ 34.8	$ (28.4)	$ (132.3)
Net Income (Loss) Available to Common Stockholders, Diluted									$ 34.8	$ (28.4)	$ (132.3)
Weighted-average shares outstanding									65.2	63.9	51.8
Effect of TEUs on weighted-average shares for basic earnings (loss) per share									2.6	4.9	4.9
Weighted-average shares for basic (loss) earnings per share									67.8	68.8	56.7
Effect of dilutive securities									2.1	0	0
Weighted-average shares for diluted earnings (loss) per share									69.9	68.8	56.7
Basic (loss) earnings per common share	$ 0.16	$ (0.93)	$ (0.11)	$ 1.36	$ (0.58)	$ 0	$ 0.02	$ 0.16	$ 0.51	$ (0.41)	$ (2.33)
Diluted (loss) earnings per common share	$ 0.16	$ (0.93)	$ (0.11)	$ 1.22	$ (0.58)	$ 0	$ 0.02	$ 0.15	$ 0.50	$ (0.41)	$ (2.33)
Stock Options
Earnings Per Share, Diluted
Effect of dilutive securities									1.8	0	0
Restricted Stock
Earnings Per Share, Diluted
Effect of dilutive securities									0.3	0	0

Earnings (loss) per Share Antid

Earnings (loss) per Share Antidilutive shares excluded from earnings per share (Details) - shares shares in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.3	4.3	4.2
Stock Appreciation Rights
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0.2	0.3
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0.5	0.5
Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	9.1	9.1	11

Supplemental Operations State67

Supplemental Operations Statement and Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Supplemental Operations Statement and Cash Flow Information [Abstract]
Advertising and promotion expenses	$ 159.7	$ 184.2	$ 137.3
Repair and maintenance expenses	162.6	141.6	92.1
Research and development expenses	18.6	16.3	16.8
Rent expense	41.8	32	23.3
Interest income	(6.8)	(2.7)	(0.8)
Interest paid	333.6	309.6	235.5
Income taxes paid	$ 29.6	$ 73.4	$ 46.4

Supplemental Balance Sheet In68

Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Receivables, net
Trade	$ 421.6	$ 354.9
Income tax receivable	46.4	23.6
Other	14.2	8.1
Gross receivables	482.2	386.6
Allowance for doubtful accounts	(1.6)	(1.6)
Receivables, net	480.6	385
Inventories
Raw materials and supplies	129.8	112.4
Work in process	16.9	17.4
Finished products	395.6	339.3
Flocks	31.2	34
Inventories	573.5	503.1
Other Assets
Pension asset	154.6	0
Other	29.7	15.9
Other Assets	184.3	15.9
Accounts Payable
Trade	306.5	228.8
Book cash overdrafts	17.8	26.6
Other	11.7	9
Accounts payable	336	264.4
Current Liabilities
Advertising and promotion	74.5	95.8
Accrued interest	36.5	55.2
Accrued compensation	89.9	103.9
Hedging liabilities	54.6	5.5
Accrued legal settlements	8.6	37.3
Other	82.2	59.6
Other current liabilities	346.3	357.3
Other Liabilities
Pension and other postretirement benefit obligations	83.5	83.2
Hedging liabilities - non-current	188.9	313.2
Accrued compensation - non-current	29.2	22.7
Other	26.2	21.2
Other Liabilities	$ 327.8	$ 440.3

Allowance for Doubtful Accoun69

Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Allowance For Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of year	$ 1.6	$ 2	$ 1.4
Provision charged to expense	0.3	1.2	0.7
Write-offs, less recoveries	(0.3)	(1.6)	(0.3)
Impact of acquisitions	0	0	0.2
Balance, end of year	$ 1.6	$ 1.6	$ 2

Derivative Financial Instrume70

Derivative Financial Instruments and Hedging Derivative Financial Instruments and Hedging Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2017
Derivative [Line Items]
Cash Flow Hedge Loss to be Reclassified During Next 12 Months		$ 0.7
Collateral Already Posted	$ 6.1	$ 2.9
Forward Contracts
Derivative [Line Items]
Remaining Maturity	17 months

Derivative Financial Instrume71

Derivative Financial Instruments and Hedging (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Level 2
Derivatives, Fair Value
Asset Derivatives:	$ 5.9	$ 3
Liability Derivatives:	243.5	318.7
Portion Designated as Hedging Instruments | Level 2
Derivatives, Fair Value
Asset Derivatives:	1.4	0
Liability Derivatives:	30	0
Commodity contracts | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0.5	0.6
Commodity contracts | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	1.9	3.3
Commodity contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	53.8	49.8
Commodity contracts | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Commodity contracts | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	0
Energy contracts | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	3.8	2.4
Energy contracts | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0.3	0.2
Energy contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	25.6	23.6
Energy contracts | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	0	0
Energy contracts | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0	0
Foreign exchange contracts | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	1.3	0
Foreign exchange contracts | Level 2 | Other assets
Derivatives, Fair Value
Asset Derivatives:	0.3	0
Foreign exchange contracts | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	1.5	0
Foreign exchange contracts | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	23.6	0
Foreign exchange contracts | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	3.8	0
Foreign exchange contracts | Portion Designated as Hedging Instruments
Derivatives, Fair Value
Derivative, Notional Amount	20.9	0
Foreign exchange contracts | Portion Designated as Hedging Instruments | Level 2 | Prepaid expenses and other current assets
Derivatives, Fair Value
Asset Derivatives:	1.1	0
Foreign exchange contracts | Portion Designated as Hedging Instruments | Level 2 | Other assets
Derivatives, Fair Value
Asset Derivatives:	0.3	0
Foreign exchange contracts | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	1.5	0
Foreign exchange contracts | Portion Designated as Hedging Instruments | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	23.6	0
Currency Swap | Portion Designated as Hedging Instruments
Derivatives, Fair Value
Derivative, Notional Amount	448.7	0
Interest rate swaps | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	50.9	2
Interest rate swaps | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	165.3	313.2
Interest rate swaps | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	76.1	77.6
Interest rate swaps | Portion Designated as Hedging Instruments
Derivatives, Fair Value
Derivative, Notional Amount	1,000	0
Interest rate swaps | Portion Designated as Hedging Instruments | Level 2 | Other current liabilities
Derivatives, Fair Value
Liability Derivatives:	0.7	0
Interest rate swaps | Portion Designated as Hedging Instruments | Level 2 | Other liabilities
Derivatives, Fair Value
Liability Derivatives:	4.2	0
Interest rate swap, rate lock swaps [Member] | Not Designated as Hedging Instrument
Derivatives, Fair Value
Derivative, Notional Amount	$ 1,649.3	$ 1,649.3

Derivative Financial Instrume72

Derivative Financial Instruments and Hedging Gain (Loss) recognized in earnings from derivative instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Commodity contracts | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in Statement of Operations	$ (0.4)	$ 7.5	$ (5.2)
Energy contracts | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in Statement of Operations	(1.3)	1.2	12.8
Foreign exchange contracts | Selling, general and administrative expenses
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in Statement of Operations	0.8	0	0
Interest rate swaps | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in Statement of Operations	(102.1)	182.9	$ 92.5
Portion Designated as Hedging Instruments | Foreign exchange contracts | Selling, general and administrative expenses
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in OCI	(1.6)	0
Loss Reclassified from Accumulated OCI into Earnings	0	0
Loss Recognized in Earnings [amount excluded from effectiveness testing]	0	0
Portion Designated as Hedging Instruments | Interest rate swaps | Interest expense, net
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in OCI	5.6	0
Loss Reclassified from Accumulated OCI into Earnings	0.7	0
Loss Recognized in Earnings [amount excluded from effectiveness testing]	0	0
Portion Designated as Hedging Instruments | Currency Swap | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Recognized in OCI	14.8	0
Loss Reclassified from Accumulated OCI into Earnings	0	0
Loss Recognized in Earnings [amount excluded from effectiveness testing]	$ 10.3	$ 0

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Impairment of goodwill and other intangible assets	$ 26.5	$ 0	$ 0	$ 0	$ 26.5	$ 0	$ 60.8
Impairment of Intangible Assets (Excluding Goodwill)							3.8
Deferred compensation investment	15.4				15.4	11.5
Derivative Asset	5.9				5.9	3
Assets, Fair Value Disclosure	21.3				21.3	14.5
Deferred compensation liabilities	22.5				22.5	17.3
Derivative Liabilities	243.5				243.5	318.7
Liabilities, Fair Value Disclosure	266				266	336
Loss on write-down of assets held for sale					0.2	(9.3)	(34.2)
Goodwill, Impairment Loss						0	57
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Deferred compensation investment	15.4				15.4	11.5
Derivative Asset	0				0	0
Assets, Fair Value Disclosure	15.4				15.4	11.5
Deferred compensation liabilities	0				0	0
Derivative Liabilities	0				0	0
Liabilities, Fair Value Disclosure	0				0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt, Fair Value Disclosure	7,343.4				7,343.4	4,852.2
Deferred compensation investment	0				0	0
Derivative Asset						3
Assets, Fair Value Disclosure	5.9				5.9	3
Deferred compensation liabilities	22.5				22.5	17.3
Derivative Liabilities						318.7
Liabilities, Fair Value Disclosure	266				266	336
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of assets held-for-sale	$ 0				0	10.1	$ 11.4
Increase (Decrease) in Assets Held-for-sale						9.6
Gain (Loss) on Disposition of Property Plant Equipment					0.2
Loss on write-down of assets held for sale						(9.3)
Proceeds from Sale of Property Held-for-sale					$ (10.3)	(1.6)
Modesto, California Facility | Facility Closing | Prepaid expenses and other current assets | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of assets held-for-sale						4.3
Farmers Branch, Texas Facility | Facility Closing | Prepaid expenses and other current assets | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value of assets held-for-sale						$ 5.8

Long Term Debt (Details)

Long Term Debt (Details) - USD ($)	3 Months Ended					12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument
Capital leases			$ 0			$ 200,000	$ 0
Long-term Debt and Capital Lease Obligations, Including Current Maturities			4,600,300,000			7,212,200,000	4,600,300,000
Current portion of long-term debt			(12,300,000)			(22,100,000)	(12,300,000)
Debt issuance costs, net			(53,500,000)			(81,800,000)	(53,500,000)
Plus: Unamortized premium			16,700,000			40,800,000	16,700,000
Total long-term debt			4,551,200,000			7,149,100,000	4,551,200,000
Debt Covenant, Leverage Ratio						$ 4.25
Debt Covenant, Percentage of Revolving Credit Commitments						30.00%
Debt covenant, interest coverage ratio						$ 2
Loss on extinguishment of debt, net						222,900,000	86,400,000	$ 30,000,000
Payment for Debt Extinguishment or Debt Prepayment Cost						219,800,000	88,000,000	0
Repayments of Long-term Debt						$ 2,088,400,000	1,632,200,000	1,225,100,000
Debt Instruments, Covenant Compliance, Percentage of Revolving Credit Commitments						30.00%
Revolving Credit Facility
Debt Instrument
Debt Covenant, Leverage Ratio		$ 4.25
Debt Covenant, Percentage of Revolving Credit Commitments		30.00%
Debt Covenant, Maximum Undischarged Judgments		$ 75,000,000
Line of Credit Facility, Current Borrowing Capacity		800,000,000
Letters of Credit Outstanding, Amount						$ 10,000,000
Line of Credit Facility, Remaining Borrowing Capacity						$ 790,000,000
Revolving Credit Facility | Minimum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage						0.25%
Revolving Credit Facility | Maximum
Debt Instrument
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage						0.375%
Line of Credit
Debt Instrument
Line of Credit Facility, Current Borrowing Capacity		50,000,000
Senior Notes
Debt Instrument
Debt issuance costs, net						$ (7,200,000)
Debt Instrument, Issuance Price, Percentage of Par Value						105.50%
Debt Instrument, Increase, Additional Borrowings						$ 784,000,000
Senior Notes | 5.50% Senior Notes maturing March 2025
Debt Instrument
Long-term Debt			0			1,000,000,000	0
Senior Notes		$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage		5.50%
Senior Notes | 5.75% Senior Notes maturing March 2027
Debt Instrument
Long-term Debt			0			1,500,000,000	0
Senior Notes		$ 750,000,000
Debt Instrument, Interest Rate, Stated Percentage		5.75%
Senior Notes | 5.50% and 5.75% Senior Notes
Debt Instrument
Debt issuance costs, net		$ (24,600,000)
Debt Instrument, Increase, Additional Borrowings		$ 1,725,400,000
Senior Notes | Additional Issuance of 5.75% Senior Notes Maturing in March 2027
Debt Instrument
Debt Instrument, Additional Debt Issued						$ 750,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.75%
Senior Notes | 5.00% Senior Notes maturing August 2026
Debt Instrument
Long-term Debt			1,750,000,000			$ 1,750,000,000	1,750,000,000
Debt issuance costs, net			(24,300,000)				(24,300,000)
Senior Notes			$ 1,750,000,000				$ 1,750,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.00%				5.00%
Debt Instrument, Increase, Additional Borrowings			$ 1,725,700,000
Senior Notes | 7.75% Senior Notes maturing March 2024
Debt Instrument
Long-term Debt			800,000,000			0	$ 800,000,000
Plus: Unamortized premium						$ 63,000,000
Senior Notes				$ 800,000,000				$ 800,000,000
Debt Instrument, Interest Rate, Stated Percentage	7.75%			7.75%		6.75%		7.75%
Loss on extinguishment of debt, net						$ 58,500,000
Repayments of Long-term Debt						875,000,000
Repayments of Debt	$ 800,000,000
Write off of Deferred Debt Issuance Cost						8,900,000
Write-off of Unamortized Debt Premium						13,400,000
Senior Notes | 8.00% Senior Notes maturing July 2025
Debt Instrument
Long-term Debt			400,000,000			137,500,000	400,000,000
Senior Notes				$ 400,000,000				$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage	8.00%			8.00%				8.00%
Repayments of Debt	$ 262,500,000
Senior Notes | 6.00% Senior Notes maturing December 2022
Debt Instrument
Long-term Debt			$ 630,000,000			630,000,000	$ 630,000,000
Debt issuance costs, net					$ (11,000,000)
Senior Notes					630,000,000
Debt Instrument, Interest Rate, Stated Percentage			6.00%				6.00%
Debt Instrument, Increase, Additional Borrowings					$ 619,000,000
Senior Notes | 6.75% Senior Notes maturing December 2021
Debt Instrument
Long-term Debt			$ 875,000,000			0	$ 875,000,000
Senior Notes | 7.375% Senior Notes maturing February 2022
Debt Instrument
Long-term Debt			$ 133,000,000			0	$ 133,000,000
Plus: Unamortized premium						$ 4,900,000
Debt Instrument, Interest Rate, Stated Percentage			7.375%			7.375%	7.375%
Loss on extinguishment of debt, net						$ 4,000,000	$ 78,600,000
Payment for Debt Extinguishment or Debt Prepayment Cost							88,000,000
Repayments of Long-term Debt						133,000,000	1,242,000,000
Write off of Deferred Debt Issuance Cost						1,200,000	12,400,000
Write-off of Unamortized Debt Premium						2,100,000	21,800,000
Senior Notes | 7.75% and 8.00% Senior Notes
Debt Instrument
Debt issuance costs, net				$ (12,100,000)				$ (12,100,000)
Loss on extinguishment of debt, net						160,400,000
Payment for Debt Extinguishment or Debt Prepayment Cost						151,900,000
Write off of Deferred Debt Issuance Cost						8,500,000
Debt Instrument, Increase, Additional Borrowings				$ 1,187,900,000
Term Loan
Debt Instrument
Long-term Debt			$ 0			2,194,500,000	0
Loss on extinguishment of debt, net						7,800,000	30,000,000
Term Loan | Joinder No. 1 Term Loan [Member]
Debt Instrument
Loans Payable to Bank	1,200,000,000
Proceeds from Issuance of Unsecured Debt	1,200,000,000
Term Loan | Joinder No. 2 Term Loan
Debt Instrument
Loans Payable to Bank	1,000,000,000
Proceeds from Issuance of Unsecured Debt	$ 1,000,000,000
Debt Instrument, Interest Rate, Effective Percentage	3.49%
Debt Instrument, Periodic Payment, Principal	$ 5,500,000
Amortization of Debt Issuance Costs						23,700,000
TEUs
Debt Instrument
Long-term Debt			11,000,000			0	11,000,000
Bonds | 4.57% 2012 Series Bond maturing September 2017
Debt Instrument
Long-term Debt			$ 1,300,000			0	$ 1,300,000
Revolver Incremental Borrowing Capacity
Debt Instrument
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases						700,000,000
Debt Covenant, Proforma Consolidated Leverage Ratio						6.50
Debt Covenant, Proforma Senior Secured Leverage Ratio						3
Debt Issuance Costs, Line of Credit Arrangements, Gross						4,600,000
Debt Covenant, Quarterly Interest Ratio						$ 2
Base Rate | Revolving Credit Facility | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate						0.75%
Base Rate | Revolving Credit Facility | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate						1.25%
Base Rate | Term Loan | Joinder No. 2 Term Loan
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	1.25%
Eurodollar | Revolving Credit Facility | Minimum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate						1.75%
Eurodollar | Revolving Credit Facility | Maximum
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate						2.25%
Eurodollar | Term Loan | Joinder No. 2 Term Loan
Debt Instrument
Debt Instrument, Basis Spread on Variable Rate	2.25%

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies(Details)	Dec. 08, 2016USD ($)	Sep. 30, 2017USD ($)plaintiff_groupdefendant	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)
Loss Contingencies [Line Items]
Accrued legal settlements		$ 8,600,000	$ 37,300,000
Litigation Settlement, Expense		74,500,000	28,500,000	$ 0
Future Minimum Payments Due and Rent Expense
2,018		22,400,000
2,019		25,300,000
2,020		23,700,000
2,021		22,800,000
2,022		20,600,000
Thereafter		$ 38,100,000
Michael Foods
Loss Contingencies [Line Items]
Accrued legal settlements			$ 28,500,000
Operating Segments | Michael Foods
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number		22
Loss Contingency, Pending Claims, Other Defendants | defendant		20
Loss Contingency, Pending Claims, Number of Plaintiff Groups | plaintiff_group		3
Litigation Settlement	$ 75,000,000

Pension and Other Postretirem76

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, 2017	Sep. 30, 2016	Sep. 30, 2015
Amounts recognized in assets or liabilities [Abstract]
Other liabilities	$ (83.5)	$ (83.2)
Other Benefits
Change in benefit obligation [roll forward]
Service cost	0.6	1	$ 2
Interest cost	2	4	4.8
North America | Pension Benefits
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	71.2	58.1
Service cost	4.1	4	3.8
Interest cost	2.5	2.5	2.2
Plan participants' contributions	0.6	0.6
Plan Amendment	0	0.5
Actuarial (gain) loss	(1)	8
Business combinations	25.5	0
Benefits paid	(3)	(2.7)
Currency translation	0.7	0.2
Benefit obligation at end of period	100.6	71.2	58.1
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	54.3	44.4
Actual return on plan assets	5.4	5.5
Business combinations	15.2	0
Employer contributions	7.7	6.3
Currency translation	0.7	0.2
Fair value of plan assets at end of period	80.9	54.3	44.4
Defined benefit plan, funded status of plan [Abstract]
Funded status	(19.7)	(16.9)
Amounts recognized in assets or liabilities [Abstract]
Other assets	1.5	0
Other liabilities	(21.2)	(16.9)
Net amount recognized	(19.7)	(16.9)
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	0.6	19.1
Prior service cost (credit)	14.3	0.8
Total	14.9	19.9
Weighted-average assumptions used to determine benefit obligation [Abstract]
Plans with benefit obligations in excess of plan assets, aggregate benefit obligation	98.3	68.6
North America | Other Benefits
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	68.6	112.4
Service cost	0.6	1
Interest cost	2	4
Plan Amendment	(0.1)	(36.1)
Actuarial (gain) loss	(4.4)	(11.3)
Currency translation	0.4	0.2
Benefit obligation at end of period	65	68.6	112.4
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	0
Employer contributions	2.1	1.6
Fair value of plan assets at end of period	0	0
Defined benefit plan, funded status of plan [Abstract]
Funded status	(65)	(68.6)
Amounts recognized in assets or liabilities [Abstract]
Other current liabilities	(2.7)	(2.3)
Other liabilities	(62.3)	(66.3)
Net amount recognized	(65)	(68.6)
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	8.6	13.6
Prior service cost (credit)	(28.8)	(33.5)
Total	(20.2)	(19.9)
Weighted-average assumptions used to determine benefit obligation [Abstract]
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ 2.1	$ 1.6
U.S. Plans, Pension Benefits | UNITED STATES
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	3.77%	3.54%
U.S. Plans, Pension Benefits | UNITED STATES | Pension Benefits
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	3.86%	3.66%
Rate of compensation increase	3.00%	3.00%
International Pension Plans | Other International
Weighted-average assumptions used to determine benefit obligation [Abstract]
Plans with benefit obligations in excess of plan assets, aggregate benefit obligation	$ 690.4
International Pension Plans | Other International | Pension Benefits
Change in benefit obligation [roll forward]
Benefit obligation at beginning of period	0	$ 0
Service cost	1.7	0	0
Interest cost	4.9	0	0
Plan participants' contributions	0.6	0
Plan Amendment	0	0
Actuarial (gain) loss	(46.4)	0
Business combinations	746	0
Benefits paid	(6.2)	0
Currency translation	23	0
Benefit obligation at end of period	723.6	0	0
Change in fair value of plan assets [roll forward]
Fair value of plan assets at beginning of period	0	0
Actual return on plan assets	0.3	0
Business combinations	852.2	0
Employer contributions	2.4	0
Currency translation	27.4	0
Fair value of plan assets at end of period	876.7	0	$ 0
Defined benefit plan, funded status of plan [Abstract]
Funded status	153.1	0
Amounts recognized in assets or liabilities [Abstract]
Other assets	153.1	0
Other liabilities	0	0
Net amount recognized	153.1	0
Amounts recognized in accumulated other comprehensive income or loss [Abstract]
Net actuarial (gain) loss	(40.2)	0
Prior service cost (credit)	0	0
Total	$ (40.2)	$ 0
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	2.72%
Rate of compensation increase	2.70%
International Pension Plans | CANADA
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	3.69%	3.23%
Rate of compensation increase	2.75%	2.75%
International Pension Plans | CANADA | Pension Benefits
Weighted-average assumptions used to determine benefit obligation [Abstract]
Discount rate	3.63%	3.18%
Rate of compensation increase	2.69%	2.75%

Pension and Other Postretirem77

Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	Feb. 28, 2016	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss			$ (47.8)	$ (6.2)	$ 9.5
Estimated net actuarial loss to be reclassified from accumulated other comprehensive income into net periodic benefit cost			0.3
Prior service cost expected to be reclassified from accumulated other comprehensive income into net periodic benefit cost			(4.7)
Other Benefits
Components of net periodic benefit cost [Abstract]
Service cost			0.6	1	2
Interest cost			2	4	4.8
Recognized net actuarial loss			0.7	1.6	1.4
Recognized prior service cost			(4.8)	(3.8)	(1.6)
Net periodic benefit cost			(1.5)	2.8	6.6
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	4.60%	4.22%
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss			(4.4)	(11.3)	3.1
Recognized loss			(0.7)	(1.6)	(1.4)
Plan Amendment			(0.1)	(36.1)	0
Recognized prior service cost			4.8	3.8	1.6
Currency translation			0.1	(0.1)	(0.3)
Total recognized in other comprehensive income or loss (before tax effects)			(0.3)	(45.3)	3
North America | Pension Benefits
Components of net periodic benefit cost [Abstract]
Service cost			4.1	4	3.8
Interest cost			2.5	2.5	2.2
Expected return on plan assets			(3.2)	(2.6)	(2.4)
Recognized net actuarial loss			1.6	1.1	0.9
Recognized prior service cost			0.2	0.3	0.3
Net periodic benefit cost			5.2	5.3	4.8
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss			(3.1)	5.1	6.4
Recognized loss			(1.6)	(1.1)	(0.9)
Plan Amendment			0	0.5	0
Recognized prior service cost			(0.2)	(0.3)	(0.3)
Currency translation			(0.1)	0	0
Total recognized in other comprehensive income or loss (before tax effects)			(5)	4.2	$ 5.2
Estimated net actuarial loss to be reclassified from accumulated other comprehensive income into net periodic benefit cost			1.1
Prior service cost expected to be reclassified from accumulated other comprehensive income into net periodic benefit cost			0.1
North America | Other Benefits
Components of net periodic benefit cost [Abstract]
Service cost			0.6	1
Interest cost			$ 2	$ 4
U.S. Plans, Pension Benefits | North America | Pension Benefits
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate			3.66%	4.55%	4.56%
Rate of compensation increase			2.99%	3.00%	3.00%
Expected return on plan assets			5.33%	5.20%	5.72%
U.S. Plans, Pension Benefits | UNITED STATES | Other Benefits
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate	4.60%	4.22%	3.54%		4.61%
International Pension Plans | North America | Pension Benefits
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate			3.18%	3.82%	4.25%
Rate of compensation increase			2.50%	2.75%	2.75%
Expected return on plan assets			6.00%	6.00%	6.00%
International Pension Plans | CANADA | Other Benefits
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate			3.23%	3.91%	4.45%
Rate of compensation increase			2.75%	2.75%	2.75%
International Pension Plans | Other International | Pension Benefits
Components of net periodic benefit cost [Abstract]
Service cost			$ 1.7	$ 0	$ 0
Interest cost			4.9	0	0
Expected return on plan assets			(7.5)	0	0
Net periodic benefit cost			$ (0.9)	$ 0	$ 0
Weighted-average assumptions used to determine net benefit cost [Abstract]
Discount rate			2.61%	0.00%	0.00%
Rate of compensation increase				0.00%	0.00%
Expected return on plan assets			3.52%	0.00%	0.00%
Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract]
Net (gain) loss			$ (39.3)	$ 0	$ 0
Currency translation			(0.9)	0	0
Total recognized in other comprehensive income or loss (before tax effects)			$ (40.2)	$ 0	$ 0

Pension and Other Postretirem78

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, 2017	Sep. 30, 2016	Sep. 30, 2015
Equities
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations		49.80%
North America
Defined Benefit Plan Disclosure
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 5.2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Allocation Of Assets, Other Securities	1.00%
Actual allocations, index funds	69.60%	81.00%
Pension plan's assets at fair value	$ 80.9	$ 54.3	$ 44.4
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	34	17.2
Investments Net Asset Value	46.9	37.1
North America | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	20.8	6.6
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	20.8	6.6
Investments Net Asset Value	0	0
North America | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	13.2	10.6
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	13.2	10.6
Investments Net Asset Value	$ 0	0
North America | Equities
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	56.00%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	58.30%
Pension plan's assets at fair value	$ 16.4	6.7
Investments Net Asset Value	30.7	20.3
North America | Equities | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	7.8	0
Investments 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	8.6	6.7
Investments Net Asset Value	$ 0	$ 0
North America | Debt Securities
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	37.00%	42.40%
North America | Bonds
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 11.3	$ 6
North America | Bonds | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	11.3	6
North America | Bonds | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
North America | Pooled Assets [Member]
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	4.5	4.3
North America | Pooled Assets [Member] | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	0	0
North America | Pooled Assets [Member] | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	0	0
North America | Fixed income
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	4.6	3.9
Investments Net Asset Value	9.6	8.9
North America | Fixed income | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Investments Net Asset Value	0	0
North America | Fixed income | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	4.6	3.9
Investments Net Asset Value	$ 0	$ 0
North America | Real assets
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	3.70%	6.60%
Pension plan's assets at fair value	$ 0.9	$ 0
Investments Net Asset Value	2.1	3.6
North America | Real assets | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	1	0
Investments Net Asset Value	0	0
North America | Real assets | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0	0
Investments Net Asset Value	0	$ 0
North America | Cash and Cash Equivalents
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations		1.20%
Pension plan's assets at fair value	0.8	$ 0.6
North America | Cash and Cash Equivalents | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0.8	0.6
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
Other International
Defined Benefit Plan Disclosure
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 9.6
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Allocation Of Assets, Other Securities	0.10%
Actual allocations, index funds	25.60%
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	$ 776.9
Other International | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	756.3
Other International | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Fair Value of Plan Assets not Measured at NAV	$ 20.6
Other International | Debt Securities
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	75.90%
Other International | Liability Hedging Instruments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	22.80%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	23.30%
Other International | Fixed income
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%
Other International | Real assets
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	8.00%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	0.40%
Other International | Cash and Cash Equivalents
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.20%
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Defined Benefit Plan, Actual Plan Asset Allocations	0.30%
Other International | Corporate Debt Securities [Member]
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	63.00%
International Pension Plans | Other International
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	$ 876.7	$ 0	$ 0
Investments Net Asset Value	99.8
International Pension Plans | Other International | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	756.3
Investments Net Asset Value	0
International Pension Plans | Other International | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	20.6
Investments Net Asset Value	0
International Pension Plans | Other International | Bonds
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	461.7
International Pension Plans | Other International | Bonds | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	441
International Pension Plans | Other International | Bonds | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	20.6
International Pension Plans | Other International | Liability Hedging Instruments
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	204.2
International Pension Plans | Other International | Liability Hedging Instruments | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	204
International Pension Plans | Other International | Liability Hedging Instruments | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0
International Pension Plans | Other International | Fixed income
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	108.3
Investments Net Asset Value	95
International Pension Plans | Other International | Fixed income | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	108
Investments Net Asset Value	0
International Pension Plans | Other International | Fixed income | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0
Investments Net Asset Value	0
International Pension Plans | Other International | Real assets
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	3.9
International Pension Plans | Other International | Real assets | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	0
International Pension Plans | Other International | Real assets | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	0
International Pension Plans | Other International | Cash and Cash Equivalents
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	2.7
International Pension Plans | Other International | Cash and Cash Equivalents | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	2.7
International Pension Plans | Other International | Cash and Cash Equivalents | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Pension plan's assets at fair value	0
International Pension Plans | Other International | Other Investments [Member]
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	0.9
International Pension Plans | Other International | Other Investments [Member] | Level 1
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	0
International Pension Plans | Other International | Other Investments [Member] | Level 2
Defined Benefit Plan, Actual Plan Asset Allocation [Abstract]
Investments Net Asset Value	$ 0

Pension and Other Postretirem79

Pension and Other Postretirement Benefits - Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Effect on postretirement benefit obligation, increase	$ 6.7
Effect on postretirement benefit obligation, decrease	(5.5)
Effect on total service and interest cost, increase	0.3
Effect on total service and interest cost, decrease	(0.2)
Estimated net actuarial loss to be reclassified from accumulated other comprehensive income into net periodic benefit cost	0.3
Prior service cost expected to be reclassified from accumulated other comprehensive income into net periodic benefit cost	$ 4.7
U.S. Plans, Pension Benefits | Other Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%	5.00%
U.S. Plans, Pension Benefits | Participants Under 65 | Other Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7.00%	7.50%
U.S. Plans, Pension Benefits | Participants Over 65 | Other Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	5.80%	6.00%
International Pension Plans | CANADA | Other Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.50%
International Pension Plans | CANADA | Participants Under 65 | Other Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	6.50%
International Pension Plans | CANADA | Participants Over 65 | Other Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7.00%

Pension and Other Postretirem80

Pension and Other Postretirement Benefits - Expected Future Benefit Payments and Related Federal Subsidy Receipts (Details) $ in Millions	Sep. 30, 2017USD ($)
Disclosure of Expected Gross Prescription Drug Subsidy Receipts [Abstract]
Year 1	$ 0
Year 2	0
Year 3	0.1
Year 4	0.1
Year 5	0.1
Years 6-10	1
Pension benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Year 1	23
Year 2	24.2
Year 3	24.6
Year 4	25.5
Year 5	26.8
Year 6 and thereafter	153.3
Other benefits
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Year 1	2.7
Year 2	3
Year 3	3.2
Year 4	3.3
Year 5	3.5
Year 6 and thereafter	$ 18.2

Pension and Other Postretirem81

Pension and Other Postretirement Benefits Defined contribution plan expense (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Retirement Benefits [Abstract]
Defined Contribution Plan, Cost	$ 18.2	$ 15.6	$ 11.7

Stock-Based Compensation Plan82

Stock-Based Compensation Plans - Stock-Based Compensation Plans Narrative (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017USD ($)$ / sharesshares	Sep. 30, 2016USD ($)$ / sharesshares	Sep. 30, 2015USD ($)shares
Share-based Payment Award [Line Items]
Share-based Compensation Arrangement , Maximum Award Vesting Period	10 years
Matching contribution on Director Deferred Compensation	33.00%
Stock Based Compensation Awards [Abstract]
Stock-based Compensation Expense | $	$ 30.7	$ 25.6	$ 29.2
Recognized deferred tax beneft | $	9.7	$ 8	$ 10.6
Compensation cost related to nonvested awards not yet recognized | $	$ 44.4
Awards not yet recognized. weighted average period to be recognized	2 years 2 months 10 days
Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Number of Employees Affected		25	4
Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Incremental Compensation Cost | $		$ 2.2	$ 8
Stock Settled
Stock Based Compensation Awards [Abstract]
Exercised, Total Intrinsic Value | $	$ 0.6	5.1	$ 2.1
Restricted Stock Awards [Abstract]
Granted	0		40,000
2012 Long-Term Incentive Plan
Restricted Stock Awards [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	6,500,000
2016 Long-Term Incentive Plan
Restricted Stock Awards [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	2,400,000
Stock Settled
Restricted Stock Awards [Abstract]
Fair value of restricted stock awards vested | $	$ 10.5	$ 32	$ 9.3
Nonvestsed restricted stock awards	730,040	543,502
Grant date value per share | $ / shares	$ 63.55	$ 54.11
Granted	342,778
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number	8,500	12,500
Stock Settled | 2016 Long-Term Incentive Plan
Restricted Stock Awards [Abstract]
Granted	10,200	15,000

Stock-Based Compensation Plan83

Stock-Based Compensation Plans - Stock Appreciation Rights Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Stock Appreciation Rights
Stock-based Compensation Expense	$ 30.7	$ 25.6	$ 29.2
Cash Settled
Stock Appreciation Rights
Outstanding	104,500	105,000
Granted	0
Exercised	(500)
Forfeited	0
Expired	0
Vested And Expected To Vest	104,500
Exercisable	71,166
Outstanding, Weighted Average Exercise Price	$ 46.43	$ 46.29
Granted, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	18.10
Forfeited, Weighted Average Exercise Price	0
Expired, Weighted Average Exercise Price	0
Vested And Expected To Vest, Weighted Average Exercise Price	46.43
Exercisable, Weighted Average Exercise Price	$ 45.83
Outstanding, Weighted Average Remaining Contractual Term	7 years 4 months 24 days
Vested And Expected To Vest, Outstanding, Weighted Average Remaining Contractual Term	7 years 4 months 24 days
Exercisable, Weighted Average Remaining Contractual Term	7 years 3 months 21 days
Outstanding, Intrinsic Value	$ 4.4
Vested And Expected To Vest, Outstanding, Aggregate Intrinsic Value	4.4
Exercisable, Aggregate Intrinsic Value	$ 3
Expected Term	2 years 11 months 10 days	3 years 9 months 14 days	4 years 9 months 14 days
Expected Volatility Rate	31.65812%	32.39%	29.70%
Risk Free Interest Rate	1.64884%	0.99%	1.26%
Expected Dividend Rate	0.00%	0.00%	0.00%
Fair Value Of Awards, Per Share	$ 54.18	$ 44.44	$ 29.10
Stock Settled
Stock Appreciation Rights
Outstanding	137,831	152,831
Granted	0		40,000
Non-employee director share-based compensation			$ 0.7
Exercised	(15,000)
Forfeited	0
Expired	0
Vested And Expected To Vest	137,831
Exercisable	102,831
Outstanding, Weighted Average Exercise Price	$ 41.63	$ 42.07
Granted, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	46.19
Forfeited, Weighted Average Exercise Price	0
Expired, Weighted Average Exercise Price	0
Vested And Expected To Vest, Weighted Average Exercise Price	41.63
Exercisable, Weighted Average Exercise Price	$ 38.17
Outstanding, Weighted Average Remaining Contractual Term	5 years 8 months 10 days
Vested And Expected To Vest, Outstanding, Weighted Average Remaining Contractual Term	5 years 8 months 10 days
Exercisable, Weighted Average Remaining Contractual Term	5 years 28 days
Outstanding, Intrinsic Value	$ 6.4
Vested And Expected To Vest, Outstanding, Aggregate Intrinsic Value	6.4
Exercisable, Aggregate Intrinsic Value	5.2
Expected Term			6 years 6 months
Expected Volatility Rate			29.16%
Risk Free Interest Rate			1.58%
Expected Dividend Rate			0.00%
Fair Value Of Awards, Per Share			$ 16.72
Exercised, Total Intrinsic Value	$ 0.6	$ 5.1	$ 2.1

Stock-Based Compensation Plan84

Stock-Based Compensation Plans - Stock Option award activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Payment Award [Line Items]
Outstanding	4,198,500	4,255,500
Granted	343,000
Exercised	(400,000)
Forfeited	0
Expired	0
Vested and Expected to Vest	4,198,500
Exercisable	3,060,163
Outstanding, Weighted Average Exercise Price	$ 45.36	$ 42.15
Granted, Weighted Average Exercise Price	71.32
Exercised, Weighted Average Exercise Price	33.51
Forfeitured and Expired, Weighted Average Exercise Price	0
Vested and Expected to Vest, Weighted Average Exercise Price	45.36
Exercisable, Weighted Average Exercise Price	$ 41
Outstanding, Weighted Average Remaining Contractual Term	6 years 3 months 14 days
Vested and Expected to Vest, Weighted Average Remaining Contractual Term	6 years 3 months 14 days
Exercisable, Weighted Average Remaining Contractual Term	5 years 9 months 4 days
Outstanding, Intrinsic Value	$ 180.2
Vested and Expected to Vest, Aggregate Intrinsic Value	180.2
Exercisable, Intrinsic Value	144.7
Stock Options
Share-based Payment Award [Line Items]
Exercised, Total Intrinsic Value	$ 17.6	$ 5.1	$ 12.4
Expected Term	6 years 6 months	6 years 6 months 15 days	5 years 3 months 5 days
Expected Volatility Rate	30.60823%	29.05%	27.93%
Risk Free Interest Rate	1.91332%	1.92%	1.57%
Expected Dividend Rate	0.00%	0.00%	0.00%
Fair value per option	$ 24.80	$ 20.22	$ 7.22

Stock-Based Compensation Plan85

Stock-Based Compensation Plans - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Stock Settled
Share-based Payment Award [Line Items]
Nonvestsed restricted stock awards	730,040	543,502
Granted	342,778
Vested	(136,557)
Forfeited	(19,683)
Grant date value per share	$ 63.55	$ 54.11
Granted, Weighted Average Exercise Price	73.79
Vested, Weighted Average Exercise Price	51.60
Forfeited, Weighted Average Exercise Price	$ 63.84
Fair value of restricted stock awards vested	$ 10.5	$ 32	$ 9.3
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number	8,500	12,500
Non-employee director share-based compensation	$ 0.7	$ 0.7
Cash Settled
Share-based Payment Award [Line Items]
Restricted Stock Units valued at greater of current stock price or grant price	49,000
Grant date price of restricted stock units valued at greater of current stock price or grant price	$ 51.43
Nonvestsed restricted stock awards	100,119	154,230
Granted	0
Vested	(51,919)
Forfeited	(2,192)
Grant date value per share	$ 49.47	$ 47.66
Granted, Weighted Average Exercise Price	0
Vested, Weighted Average Exercise Price	44.41
Forfeited, Weighted Average Exercise Price	$ 42.37
Total Share-based Liabilities Paid	$ 4.1	$ 5.9	$ 3.4
2016 Long-Term Incentive Plan | Stock Settled
Share-based Payment Award [Line Items]
Granted	10,200	15,000

Tangible Equity Units (Details)

Tangible Equity Units (Details) - USD ($)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Tangible Equity Units [Line Items]
Tangible Equity Units, Number of Units Issued	2,875,000
Tangible Equity Units, Issuance Costs	$ (8,900,000)
Proceeds From Issuance of Tangible Equity Units Net	$ 278,600,000
Tangible Equity Units Unit Price	$ 100
Tangible Equity Units, Exchanged	2,800,000	100,000
Tangible Equity Units Equity Component
Tangible Equity Units [Line Items]
Tangible Equity Units, Carrying Amount	$ 85.48
Proceeds from Issuance of Tangible Equity Units, Gross	245,700,000
Tangible Equity Units, Issuance Costs	(7,600,000)
Proceeds From Issuance of Tangible Equity Units Net	238,100,000
Tangible Equity Units Debt Component
Tangible Equity Units [Line Items]
Tangible Equity Units, Carrying Amount	14.5219
Proceeds from Issuance of Tangible Equity Units, Gross	41,800,000
Tangible Equity Units, Issuance Costs	(1,300,000)
Proceeds From Issuance of Tangible Equity Units Net	$ 40,500,000
Debt Instrument, Interest Rate, Stated Percentage	5.25%
Tangible Equity Unit, Equity Component, Settlement Rate per Unit	$ 1.3125
Tangible Equity Units
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross	$ 287,500,000
Minimum
Tangible Equity Units [Line Items]
Tangible Equity Unit, Equity Component, Settlement Rate per Unit	1.7114
Long Term Debt, Current Maturities | Tangible Equity Units Equity Component
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross		$ 0
Long Term Debt, Current Maturities | Tangible Equity Units Debt Component
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross		13,300,000
Long Term Debt, Current Maturities | Tangible Equity Units
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross		13,300,000
Long-term Debt | Tangible Equity Units Equity Component
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross		0
Tangible Equity Units, Issuance Costs		0
Long-term Debt | Tangible Equity Units Debt Component
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross		28,500,000
Tangible Equity Units, Issuance Costs		1,300,000
Long-term Debt | Tangible Equity Units
Tangible Equity Units [Line Items]
Proceeds from Issuance of Tangible Equity Units, Gross		28,500,000
Tangible Equity Units, Issuance Costs		1,300,000
Additional Paid-in Capital | Tangible Equity Units Equity Component
Tangible Equity Units [Line Items]
Proceeds From Issuance of Tangible Equity Units Net		238,100,000
Additional Paid-in Capital | Tangible Equity Units Debt Component
Tangible Equity Units [Line Items]
Proceeds From Issuance of Tangible Equity Units Net		0
Additional Paid-in Capital | Tangible Equity Units
Tangible Equity Units [Line Items]
Proceeds From Issuance of Tangible Equity Units Net		$ 238,100,000
Common Stock
Tangible Equity Units [Line Items]
Tangible equity units conversion (shares)	4,700,000	200,000

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	May 04, 2015
Class of Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method	$ 317.8
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Par value of preferred stock	$ 0.01	$ 0.01
Convertible Preferred Stock, Shares Issued upon Conversion		2.1192
Preferred stock conversion	$ 0	$ (10.9)	$ 0
Upfront payment for share repurchases	(28.3)
Transaction costs paid in connection with stock repurchase contracts	(0.2)
Aggregate cash received under share repurchase agreement	$ 29.4
Common Stock, Shares, Issued	66,100,000	64,900,000		2,450,000
Proceeds from issuance of common stock, net of issuance costs	$ 0	$ 0	$ 732.7
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage	3.75%	3.75%
Par value of preferred stock	$ 0.01
Preferred Stock, Liquidation Preference Per Share	$ 100
Preferred Stock, Shares Outstanding	1,500,000	1,500,000
Convertible Preferred Stock, Shares Issued upon Conversion	2.1192
Conversion price of convertible preferred stock	$ 47.19
Preferred Stock, Redemption Price Per Share	$ 1
Percentage of conversion price, closing sale price of common stock, minimum	130.00%
Conversion price in effect, days	20 days
Redemption notice, trading day period	30 days
Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage	2.50%	2.50%
Par value of preferred stock	$ 0.01
Preferred Stock, Liquidation Preference Per Share	$ 100
Preferred Stock, Shares Outstanding	3,200,000	3,200,000
Convertible Preferred Stock, Shares Issued upon Conversion	1.8477
Conversion price of convertible preferred stock	$ 54.12
Preferred Stock, Redemption Price Per Share	$ 1
Percentage of conversion price, closing sale price of common stock, minimum	150.00%
Conversion price in effect, days	20 days
Redemption notice, trading day period	30 days
Preferred Stock
Class of Stock [Line Items]
Conversion of Stock, Shares Converted		900,000
Common Stock
Class of Stock [Line Items]
Conversion of Stock, Shares Issued		2,000,000
Common Stock
Class of Stock [Line Items]
Treasury Stock Acquired, Average Cost Per Share	$ 79.53
Treasury Stock, Value, Acquired, Cost Method	$ (317.8)
Treasury Stock, Shares, Acquired	4,000,000
Conversion of Stock, Shares Converted		(2,000,000)

Segments (Details)

Segments (Details) - USD ($)	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Entity-Wide Revenue, Major Customer, Percentage									13.00%	13.00%	10.00%
Net Sales	$ 1,448,500,000	$ 1,272,100,000	$ 1,255,400,000	$ 1,249,800,000	$ 1,260,800,000	$ 1,246,100,000	$ 1,271,100,000	$ 1,248,800,000	$ 5,225,800,000	$ 5,026,800,000	$ 4,648,200,000
Operating Income (Loss)									520,300,000	545,700,000	212,700,000
Impairment of goodwill and other intangible assets	26,500,000					$ 0	$ 0	$ 0	26,500,000	0	60,800,000
Interest expense, net									314,800,000	306,500,000	257,500,000
Loss on extinguishment of debt, net									222,900,000	86,400,000	30,000,000
Other (income) expense, net									(91,800,000)	182,900,000	92,500,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									74,400,000	(30,100,000)	(167,300,000)
Property, Plant and Equipment, Additions									190,400,000	121,500,000	120,500,000
Depreciation and amortization									323,100,000	302,800,000	272,800,000
Assets	11,876,800,000				9,360,600,000				11,876,800,000	9,360,600,000	9,163,900,000
Major customer sales, value
Segment Reporting Information [Line Items]
Net Sales									704,100,000	668,800,000	464,100,000
Non-US
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Percent of Revenue from External Customers Attributed to Foreign Countries									0.08
Disclosure on Geographic Areas, Long-Lived Assets in Foreign Countries	311,100,000				39,500,000				311,100,000	39,500,000
Operating Segments
Segment Reporting Information [Line Items]
Net Sales									5,225,800,000	5,026,800,000	4,648,200,000
Operating Income (Loss)									634,500,000	652,200,000	421,400,000
Depreciation and amortization									319,400,000	296,800,000	265,300,000
Operating Segments | Post Consumer Brands Segment
Segment Reporting Information [Line Items]
Net Sales									1,851,500,000	1,838,500,000	1,365,900,000
Operating Income (Loss)									359,000,000	302,900,000	219,500,000
Property, Plant and Equipment, Additions									65,500,000	39,200,000	20,700,000
Depreciation and amortization									118,800,000	111,700,000	77,900,000
Assets	3,611,900,000				3,558,200,000				3,611,900,000	3,558,200,000	3,642,300,000
Operating Segments | Michael Foods segment
Segment Reporting Information [Line Items]
Net Sales									2,116,200,000	2,184,700,000	2,305,700,000
Operating Income (Loss)									133,100,000	276,600,000	188,200,000
Property, Plant and Equipment, Additions									76,300,000	58,300,000	60,500,000
Depreciation and amortization									147,500,000	141,200,000	142,300,000
Assets	3,572,200,000				3,498,100,000				3,572,200,000	3,498,100,000	3,506,000,000
Operating Segments | Active Nutrition Segment
Segment Reporting Information [Line Items]
Net Sales									713,200,000	574,700,000	555,000,000
Operating Income (Loss)									96,400,000	44,700,000	(13,800,000)
Property, Plant and Equipment, Additions									3,900,000	4,400,000	7,200,000
Depreciation and amortization									25,300,000	25,000,000	26,900,000
Assets	581,300,000				624,800,000				581,300,000	624,800,000	645,400,000
Operating Segments | Private Brands Segment
Segment Reporting Information [Line Items]
Net Sales									432,500,000	429,100,000	421,700,000
Operating Income (Loss)									31,500,000	28,000,000	27,500,000
Property, Plant and Equipment, Additions									11,100,000	12,400,000	5,100,000
Depreciation and amortization									20,100,000	18,900,000	18,200,000
Assets	487,300,000				484,700,000				487,300,000	484,700,000	482,300,000
Operating Segments | Weetabix Group
Segment Reporting Information [Line Items]
Net Sales									112,400,000	0	0
Operating Income (Loss)									14,500,000	0	0
Property, Plant and Equipment, Additions									13,600,000	0	0
Depreciation and amortization									7,700,000	0	0
Assets	2,048,900,000				0				2,048,900,000	0	0
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Other Expenses									87,700,000	106,500,000	147,900,000
Property, Plant and Equipment, Additions									20,000,000	7,200,000	27,000,000
Depreciation and amortization									3,700,000	6,000,000	7,500,000
Assets	$ 1,575,200,000				$ 1,194,800,000				1,575,200,000	1,194,800,000	887,900,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Sales									0	(200,000)	(100,000)
Cereal and granola | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									1,963,900,000	1,838,500,000	1,365,900,000
Egg and egg products | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									1,419,100,000	1,417,000,000	1,511,900,000
Cheese and dairy | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									259,400,000	320,900,000	340,400,000
Refrigerated potato | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									192,300,000	179,500,000	182,300,000
Pasta | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									249,400,000	270,600,000	275,000,000
Protein-based products and supplements | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									713,200,000	574,700,000	555,000,000
Nut butters and dried nut and fruit | Operating Segments
Segment Reporting Information [Line Items]
Net Sales									432,500,000	429,100,000	421,700,000
Product Eliminations
Segment Reporting Information [Line Items]
Net Sales									$ 4,000,000	$ 3,500,000	$ 4,000,000

Summary Quarterly Financial I89

Summary Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Quarterly Financial Information [Abstract]
Net Sales	$ 1,448.5	$ 1,272.1	$ 1,255.4	$ 1,249.8	$ 1,260.8	$ 1,246.1	$ 1,271.1	$ 1,248.8	$ 5,225.8	$ 5,026.8	$ 4,648.2
Gross Profit	437.1	393.7	364.1	379.2	377.4	398.2	409.3	362.5	1,574.1	1,547.4	1,174.4
Net Income (Loss) Attributable to Parent	14.2	(59.5)	(4)	97.6	(37)	3.3	4.9	25.5	48.3	(3.3)	(115.3)
Net Earnings (Loss) Available to Common Stockholders	$ 10.9	$ (62.9)	$ (7.4)	$ 94.2	$ (40.4)	$ 0	$ 1.5	$ 10.5	$ 34.8	$ (28.4)	$ (132.3)
Basic (loss) earnings per common share	$ 0.16	$ (0.93)	$ (0.11)	$ 1.36	$ (0.58)	$ 0	$ 0.02	$ 0.16	$ 0.51	$ (0.41)	$ (2.33)
Diluted (loss) earnings per common share	$ 0.16	$ (0.93)	$ (0.11)	$ 1.22	$ (0.58)	$ 0	$ 0.02	$ 0.15	$ 0.50	$ (0.41)	$ (2.33)

Subsequent Events (Details)

Subsequent Events (Details)	Sep. 19, 2017$ / shares
Bob Evans Farms
Subsequent Event
Business Acquisition, Share Price	$ 77