Other Financial Instruments and Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2021
Fair Value Disclosures [Abstract]
Company's Municipal bond mature in 2024	$ 1.6
Company's Municipal bond mature in 2025	1.3
Company's Municipal bond mature in 2026	0.8
Company's Municipal bond mature in 2027	4.9
Company's Municipal bond mature in 2028	0.4
Company's Municipal bond mature in 2029 and beyond	9.6
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other intangible assets impairment charges	0.0	$ 150.4	$ 3.8
Pet Food Brands
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 790.3
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%
Unrealized Gain (Loss) on Investments	$ (3.8)
U.S. Retail Pet Foods [Member] | Pet Food Brands
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill	$ 790.3
U.S. Retail Pet Foods [Member] | Trademarks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other intangible assets impairment charges		$ 150.4
U.S. Retail Consumer Foods [Member] | Trademarks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other intangible assets impairment charges			$ 3.8