Accounting Policies - Narrative (Details) shares in Millions, $ in Millions				12 Months Ended
		Nov. 15, 2023 USD ($) shares	Apr. 28, 2023 USD ($) shares	Apr. 30, 2025 USD ($) Contract Facility		Apr. 30, 2024 USD ($)		Apr. 30, 2023 USD ($)	Apr. 30, 2022 USD ($)
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents				$ 69.9		$ 62.0		$ 655.8	$ 169.9
Advertising expense				181.0		182.5		160.3
Reserve for credit loss				1.5		8.7
Unrealized pre-tax gains included in accumulated other comprehensive income (loss) on available-for-sale securities				0.7		1.4
Accumulated other comprehensive income (loss)				$ (184.5)		(234.6)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for share-based payments				3 years
Compensation cost related to nonvested share-based awards not yet recognized				$ 36.0
Weighted-average period of recognition				1 year 10 months 24 days
Excess tax benefit from share-based compensation				$ 1.0		2.9		1.4
Accounting Policies (Additional Textual) [Abstract]
Charges for defined contribution plans				47.7		41.5		41.0
Property, Plant and Equipment [Line Items]
Operating Lease, Expense				118.7		121.7		113.3
Schedule of Investments [Line Items]
Realized Investment Gains (Losses)				$ 0.0		(21.5)		0.0
Concentration Risk [Line Items]
Facilities covered by union contracts | Facility				9
Number of union contracts expiring in 2025 | Contract				3
Other debt gains (charges) – net	[1]			$ 30.2	[2]	(19.5)	[2]	0.0
Accumulated other comprehensive income (loss)				6,082.6		7,693.9		7,290.8	8,140.1
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Concentration Risk [Line Items]
Accumulated other comprehensive income (loss)				$ (41.7)		(39.2)		(34.3)	$ (21.1)
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for share-based payments				1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for share-based payments				3 years
Selling, Distribution And Administrative Expense
Condensed Financial Statements, Captions [Line Items]
Distribution costs				$ 291.1		267.7		304.5
Research and development costs				51.7		49.1		47.3
Cash Equivalents [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents				0.0		0.0
Work In Process Inventory
Condensed Financial Statements, Captions [Line Items]
Work-in-process inventory				81.0		81.3
Other Noncurrent Assets
Condensed Financial Statements, Captions [Line Items]
Marketable securities and other investments				20.0		22.1
Accounts Payable [Member]
Condensed Financial Statements, Captions [Line Items]
Supplier Financing, Outstanding Payment Obligations				$ 340.4		$ 384.9
Machinery and equipment [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets				3 years
Machinery and equipment [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets				20 years
Capitalized software costs [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets				1 year
Capitalized software costs [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets				7 years
Buildings, fixtures, and improvements [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets				5 years
Buildings, fixtures, and improvements [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of assets				40 years
Post Holdings Inc.
Schedule of Investments [Line Items]
Investment in equity securities, current, ownership percentage						8.00%
Cumulative realized loss on investment in equity securities - net						$ 30.7
Realized Investment Gains (Losses)						$ 26.9		3.8
Post Holdings Inc. | Pet Food Brands
Schedule of Investments [Line Items]
Proceeds from Divestiture of Business, Equity | shares		5.4	5.4
Investment in equity securities		$ 460.9	$ 491.6					$ 487.8
Mountain Country Foods [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest acquired				20.00%
Numi, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest acquired				42.00%
Unionized Employees [Member] | Number of Employees, Total [Member]
Concentration Risk [Line Items]
Percentage of concentration risk				22.00%
Unionized Employees Subject to Union Contracts Expiring within One Year | Number of Employees, Total [Member]
Concentration Risk [Line Items]
Percentage of concentration risk				10.00%

[1] Includes special project costs related to certain divestiture, acquisition, integration, and restructuring activities. For more information, see Note 4: Special Project Costs, Note 5: Reportable Segments, and Note 8: Debt and Financing Arrangements.

[2] Includes special project costs related to certain divestiture, acquisition, integration, and restructuring activities. For more information, see Note 4: Special Project Costs and Note 8: Debt and Financing Arrangements.