Other Financial Instruments and Fair Value Measurements (Details 1) - Fair value measurements recurring [Member] - USD ($) $ in Millions		Apr. 30, 2023	Apr. 30, 2022
Financial assets (liabilities) measured at fair value on a recurring basis
Investment in equity securities	[1]	$ 487.8
Total long-term debt	[2]	(3,879.1)	$ (3,977.7)
Total financial instruments measured at fair value		(3,362.6)	(3,926.3)
Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	5.0	5.7
Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	18.6	19.9
Money Market Funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.4	1.0
Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	3.4	23.1
Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	1.3	1.7
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets (liabilities) measured at fair value on a recurring basis
Investment in equity securities	[1]	487.8
Total long-term debt	[2]	(3,879.1)	(3,977.7)
Total financial instruments measured at fair value		(3,383.0)	(3,947.4)
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	5.0	5.7
Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.0	0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.4	1.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	2.7	23.4
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	0.2	0.2
Significant Observable Inputs (Level 2)
Financial assets (liabilities) measured at fair value on a recurring basis
Investment in equity securities	[1]	0.0
Total long-term debt	[2]	0.0	0.0
Total financial instruments measured at fair value		20.4	21.1
Significant Observable Inputs (Level 2) | Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.0	0.0
Significant Observable Inputs (Level 2) | Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	18.6	19.9
Significant Observable Inputs (Level 2) | Money Market Funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.0	0.0
Significant Observable Inputs (Level 2) | Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	0.7	(0.3)
Significant Observable Inputs (Level 2) | Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	1.1	1.5
Significant Unobservable Inputs (Level 3)
Financial assets (liabilities) measured at fair value on a recurring basis
Investment in equity securities	[1]	0.0
Total long-term debt	[2]	0.0	0.0
Total financial instruments measured at fair value		0.0	0.0
Significant Unobservable Inputs (Level 3) | Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.0	0.0
Significant Unobservable Inputs (Level 3) | Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.0	0.0
Significant Unobservable Inputs (Level 3) | Money Market Funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities and other investments	[3]	0.0	0.0
Significant Unobservable Inputs (Level 3) | Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	0.0	0.0
Significant Unobservable Inputs (Level 3) | Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[4]	$ 0.0	$ 0.0

[1] The market approach is utilized to measure the fair value of equity securities. The investment in equity securities represents our equity interest in Post of approximately 8 percent as of April 30, 2023, which is valued using the trading value of Post common stock. In 2023, we recognized an unrealized pre-tax loss of $3.8 on the investment, which was included in other income (expense) – net in the Statement of Consolidated Income. For additional information, see Investment in Equity Securities in Note 1: Accounting Policies and Note 3: Divestitures.

[2] Long-term debt is composed of public Senior Notes, which are traded in an active secondary market and valued using quoted prices. For additional information, see Note 7: Debt and Financing Arrangements.

[3] Marketable securities and other investments consist of funds maintained for the payment of benefits associated with nonqualified retirement plans. The funds include equity securities listed in active markets, municipal obligations valued by a third-party using valuation techniques that utilize inputs that are derived principally from or corroborated by observable market data, and money market funds with maturities of three months or less. Based on the short-term nature of these money market funds, carrying value approximates fair value. As of April 30, 2023, our municipal obligations are scheduled to mature as follows: $1.6 in 2024, $1.3 in 2025, $0.8 in 2026, $4.9 in 2027, $0.4 in 2028, and the remaining $9.6 in 2029 and beyond. For additional information, see Marketable Securities and Other Investments in Note 1: Accounting Policies.

[4] Level 1 commodity and foreign currency exchange derivatives are valued using quoted market prices for identical instruments in active markets. Level 2 commodity and foreign currency exchange derivatives are valued using quoted prices for similar assets or liabilities in active markets. For additional information, see Note 9: Derivative Financial Instruments.