Derivative Financial Instruments (Details) - USD ($) $ in Millions	Oct. 31, 2018	Apr. 30, 2018
Other Current Assets [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	$ 23.1	$ 17.0
Other Current Assets [Member] | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.0
Other Current Assets [Member] | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	23.1	17.0
Other Current Assets [Member] | Interest rate contract | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.0
Other Current Assets [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	21.1	14.8
Other Current Assets [Member] | Foreign currency exchange contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	2.0	2.2
Other Current Liabilities [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	13.8	7.5
Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0
Other Current Liabilities [Member] | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	13.8	7.5
Other Current Liabilities [Member] | Interest rate contract | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0
Other Current Liabilities [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	13.8	6.8
Other Current Liabilities [Member] | Foreign currency exchange contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0	0.7
Other Noncurrent Assets [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	10.5	0.4
Other Noncurrent Assets [Member] | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	10.5
Other Noncurrent Assets [Member] | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.0	0.4
Other Noncurrent Assets [Member] | Interest rate contract | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	10.5
Other Noncurrent Assets [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Assets	0.0	0.4
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	0.2	0.2
Other Noncurrent Liabilities [Member] | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0
Other Noncurrent Liabilities [Member] | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.2	0.2
Other Noncurrent Liabilities [Member] | Interest rate contract | Designated as Hedging Instrument [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.0
Other Noncurrent Liabilities [Member] | Commodity contracts | Not designated as hedging instruments [Member]
Fair value of derivative instruments [Line Items]
Derivatives Instruments, Liabilities	0.2	0.2
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