Other Financial Instruments and Fair Value Measurements (Details 1) - Fair value measurements recurring [Member] - USD ($) $ in Millions		Jan. 31, 2021	Apr. 30, 2020
Financial assets (liabilities) measured at fair value on a recurring basis
Total long-term debt	[1]	$ (5,209.0)	$ (5,740.6)
Total financial instruments measured at fair value		(5,152.2)	(5,718.2)
Equity mutual funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	9.1	8.7
Municipal obligations
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	29.3	24.2
Money market funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.7	5.7
Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	19.6	(18.5)
Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	(1.9)	2.3
Fair Value, Inputs, Level 1 [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Total long-term debt	[1]	(5,209.0)	(5,032.0)
Total financial instruments measured at fair value		(5,179.7)	(5,035.7)
Fair Value, Inputs, Level 1 [Member] | Equity mutual funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	9.1	8.7
Fair Value, Inputs, Level 1 [Member] | Municipal obligations
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.0	0.0
Fair Value, Inputs, Level 1 [Member] | Money market funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.7	5.7
Fair Value, Inputs, Level 1 [Member] | Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	19.6	(18.3)
Fair Value, Inputs, Level 1 [Member] | Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	(0.1)	0.2
Fair Value, Inputs, Level 2 [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Total long-term debt	[1]	0.0	(708.6)
Total financial instruments measured at fair value		27.5	(682.5)
Fair Value, Inputs, Level 2 [Member] | Equity mutual funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.0	0.0
Fair Value, Inputs, Level 2 [Member] | Municipal obligations
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	29.3	24.2
Fair Value, Inputs, Level 2 [Member] | Money market funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.0	0.0
Fair Value, Inputs, Level 2 [Member] | Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	0.0	(0.2)
Fair Value, Inputs, Level 2 [Member] | Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	(1.8)	2.1
Fair Value, Inputs, Level 3 [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Total long-term debt	[1]	0.0	0.0
Total financial instruments measured at fair value		0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Equity mutual funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Municipal obligations
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Money market funds
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	[2]	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Commodity contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Foreign currency exchange contracts - net
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative financial instruments	[3]	$ 0.0	$ 0.0

[1] Long-term debt is composed of public Senior Notes, which are classified as Level 1, and the Term Loan, which was classified as Level 2 prior to the prepayment of the remaining balance during the third quarter of 2021. The public Senior Notes are traded in an active secondary market and valued using quoted prices. The fair value of the Term Loan was based on the net present value of each interest and principal payment calculated utilizing an interest rate derived from an estimated yield curve obtained from independent pricing sources for similar types of term loan borrowing arrangements. For additional information, see Note 8: Debt and Financing Arrangements.

[2] 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 January 31, 2021, our municipal obligations are scheduled to mature as follows: $0.3 in 2021, $1.5 in 2022, $3.5 in 2024, and the remaining $24.0 in 2025 and beyond. We do not have any municipal obligations scheduled to mature in 2023.

[3] 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 10: Derivative Financial Instruments.