Schedule of Fair Value of Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2012	May 31, 2011
Derivative [Line Items]
Asset Derivatives at Fair Value	$ 1,157	$ 1,138
Liability Derivatives at Fair Value	14,993	12,972
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value		194
Liability Derivatives at Fair Value	10,933	12,399
Derivatives Designated As Hedging Instruments | Interest Rate Contracts
Derivative [Line Items]
Liability Derivatives at Fair Value	10,684	12,399
Derivatives Designated As Hedging Instruments | Interest Rate Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	8,825	10,375
Derivatives Designated As Hedging Instruments | Interest Rate Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	1,859	2,024
Derivatives Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value		194
Liability Derivatives at Fair Value	249
Derivatives Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value		194
Derivatives Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	249
Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value	1,157	944
Liability Derivatives at Fair Value	4,060	573
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value	245	944
Liability Derivatives at Fair Value	4,060
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	245	944
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	4,060
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value	912
Liability Derivatives at Fair Value		573
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	912
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts | Other Accrued Items
Derivative [Line Items]
Liability Derivatives at Fair Value		$ 573