Schedule of Summary of Derivative Hedges (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2013
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Notional Amount	13,490
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2013-03
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2014-11
Derivatives Not Designated As Hedging Instruments | Foreign Exchange Contracts
Derivative [Line Items]
Notional Amount	50,810
Maturity Date(s)	2013-05
Cash Flow Hedges | Commodity Contracts
Derivative [Line Items]
Notional Amount	35,700
Cash Flow Hedges | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date(s)	2013-03
Cash Flow Hedges | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date(s)	2013-12
Cash Flow Hedges | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	100,000
Maturity Date(s)	2014-12