Derivative Financial Instruments (Details) (USD $) | Jul. 31, 2014 | Apr. 30, 2014 |
In Millions, unless otherwise specified |
Other Current Assets [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | $29.40 | $54.40 |
Other Current Assets [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 12.8 | 41.4 |
Other Current Assets [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 16.6 | 13 |
Other Current Assets [Member] | Commodity contracts [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 0 | 23.4 |
Other Current Assets [Member] | Commodity contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 15.4 | 11.6 |
Other Current Assets [Member] | Foreign currency exchange contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 1.2 | 1.4 |
Other Current Assets [Member] | Interest Rate Contract [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 12.8 | 18 |
Other Current Liabilities [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 19.1 | 17.4 |
Other Current Liabilities [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 0 | 10.9 |
Other Current Liabilities [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 19.1 | 6.5 |
Other Current Liabilities [Member] | Commodity contracts [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 0 | 10.9 |
Other Current Liabilities [Member] | Commodity contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 18.2 | 5.8 |
Other Current Liabilities [Member] | Foreign currency exchange contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 0.9 | 0.7 |
Other Current Liabilities [Member] | Interest Rate Contract [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | 0 | 0 |
Other Noncurrent Assets [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 4.7 | ' |
Other Noncurrent Assets [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 4.2 | ' |
Other Noncurrent Assets [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 0.5 | ' |
Other Noncurrent Assets [Member] | Commodity contracts [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 0 | ' |
Other Noncurrent Assets [Member] | Commodity contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 0.5 | ' |
Other Noncurrent Assets [Member] | Foreign currency exchange contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 0 | ' |
Other Noncurrent Assets [Member] | Interest Rate Contract [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Assets | 4.2 | ' |
Other Noncurrent Liabilities [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | 3.1 |
Other Noncurrent Liabilities [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | 3.1 |
Other Noncurrent Liabilities [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | 0 |
Other Noncurrent Liabilities [Member] | Commodity contracts [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | 0 |
Other Noncurrent Liabilities [Member] | Commodity contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | 0 |
Other Noncurrent Liabilities [Member] | Foreign currency exchange contracts [Member] | Not designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | 0 |
Other Noncurrent Liabilities [Member] | Interest Rate Contract [Member] | Designated as hedging instruments [Member] | ' | ' |
Fair value of derivative instruments [Line Items] | ' | ' |
Derivatives Instruments, Liabilities | ' | $3.10 |