Schedule of Summary of Derivative Hedges (Detail) $ in Thousands	12 Months Ended
	May 31, 2017 USD ($)
Commodity Contracts | Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Notional Amount	$ 25,331
Commodity Contracts | Derivatives Not Designated As Hedging Instruments | Minimum
Derivative [Line Items]
Maturity Date	2017-06
Commodity Contracts | Derivatives Not Designated As Hedging Instruments | Maximum
Derivative [Line Items]
Maturity Date	2018-12
Foreign Exchange Contracts | Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Notional Amount	$ 4,676
Maturity Date	2017-06
Cash Flow Hedges | Commodity Contracts
Derivative [Line Items]
Notional Amount	$ 35,529
Cash Flow Hedges | Commodity Contracts | Minimum
Derivative [Line Items]
Maturity Date	2017-06
Cash Flow Hedges | Commodity Contracts | Maximum
Derivative [Line Items]
Maturity Date	2019-06
Cash Flow Hedges | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	$ 17,203
Maturity Date	2019-09