Derivative Financial Instruments (Details) - USD ($) $ in Millions	Jul. 31, 2020	Apr. 30, 2020
Other Current Assets [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	$ 20.9	$ 17.1
Other Current Assets [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	20.4	14.7
Other Current Assets [Member] | Foreign currency exchange contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.5	2.4
Other Current Liabilities [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	18.9	33.3
Other Current Liabilities [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	17.6	33.2
Other Current Liabilities [Member] | Foreign currency exchange contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	1.3	0.1
Other Noncurrent Assets [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.1	0.0
Other Noncurrent Assets [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.1	0.0
Other Noncurrent Assets [Member] | Foreign currency exchange contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.0	0.0
Other Noncurrent Liabilities [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0	0.0
Other Noncurrent Liabilities [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0	0.0
Other Noncurrent Liabilities [Member] | Foreign currency exchange contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	$ 0.0	$ 0.0