Schedule of Summary of Derivative Hedges (Detail)	12 Months Ended
	May 31, 2016 USD ($)
Commodity Contracts | Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Notional Amount	$ 33,371,000
Commodity Contracts | Derivatives Not Designated As Hedging Instruments | Minimum
Derivative [Line Items]
Maturity Date	2016-06
Commodity Contracts | Derivatives Not Designated As Hedging Instruments | Maximum
Derivative [Line Items]
Maturity Date	2017-12
Foreign Currency Contracts | Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Notional Amount	$ 10,767,000
Maturity Date	2017-05
Cash Flow Hedges | Commodity Contracts
Derivative [Line Items]
Notional Amount	$ 87,639,000
Cash Flow Hedges | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date	2016-06
Cash Flow Hedges | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date	2017-12
Cash Flow Hedges | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	$ 17,032,000
Maturity Date	2019-09