Other Financial Instruments and Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022	Nov. 15, 2023	Apr. 28, 2023
Fair Value Disclosures [Abstract]
Company's Municipal bond mature in 2025	$ 1.5
Company's Municipal bond mature in 2026	0.8
Company's Municipal bond mature in 2027	3.8
Company's Municipal bond mature in 2028	0.4
Company's Municipal bond mature in 2029	3.4
Company's Municipal bond mature in 2030 and beyond	7.3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in equity securities	0.0	$ 487.8
Realized loss on investment in equity securities – net	(21.5)	0.0	$ 0.0
Other intangible assets impairment charges	0.0	$ 0.0	150.4
Sahale Snacks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	11.5
Post Holdings Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in equity securities, current, ownership percentage		8.00%
Cumulative realized loss on investment in equity securities - net	30.7
Realized loss on investment in equity securities – net	26.9	$ 3.8
Post Holdings Inc. | Pet Food Brands
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in equity securities		487.8		$ 460.9	$ 491.6
U.S. Retail Frozen Handheld and Spreads | Sahale Snacks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 11.5
U.S. Retail Pet Foods | Pet Food Brands
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		$ 790.3
U.S. Retail Pet Foods | Trademarks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other intangible assets impairment charges			$ 150.4