Schedule of Fair Value of Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2014	May 31, 2014
Derivative [Line Items]
Asset Derivatives at Fair Value	$ 337	$ 1,284
Liability Derivatives at Fair Value	6,324	4,475
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value	106	456
Liability Derivatives at Fair Value	5,729	4,180
Derivatives Designated As Hedging Instruments | Interest Rate Contracts
Derivative [Line Items]
Liability Derivatives at Fair Value	2,285
Derivatives Designated As Hedging Instruments | Interest Rate Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	2,102	4,180
Derivatives Designated As Hedging Instruments | Interest Rate Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	183
Derivatives Designated As Hedging Instruments | Foreign Exchange Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	106
Derivatives Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	3,444
Derivatives Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value		456
Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value	231	828
Liability Derivatives at Fair Value	595	295
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value		32
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	595	295
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	$ 231	$ 796