Schedule of Summary of Derivative Hedges (Detail) (USD $)	12 Months Ended
	May 31, 2012
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Notional amount	25,750,000
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2012-06
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2013-11
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts
Derivative [Line Items]
Notional amount	71,750,000
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2012-06
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2012-08
Cash Flow Hedges | Commodity Contracts
Derivative [Line Items]
Notional amount	7,200,000
Maturity Date(s)	2012-11
Cash Flow Hedges | Interest Rate Contracts
Derivative [Line Items]
Notional amount	100,000,000
Maturity Date(s)	2014-12