Derivative Instruments and Hedging Activities - Schedule of Fair Value of Derivative Instruments (Detail) - USD ($) $ in Thousands	May 31, 2018	May 31, 2017
Derivative [Line Items]
Asset Derivatives at Fair Value	$ 11,423	$ 8,326
Liability Derivatives at Fair Value	846	1,142
Designated as Hedging Instrument
Derivative [Line Items]
Asset Derivatives at Fair Value	6,453	7,154
Liability Derivatives at Fair Value		571
Designated as Hedging Instrument | Commodity Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value		7,154
Liability Derivatives at Fair Value		270
Designated as Hedging Instrument | Commodity Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value		159
Designated as Hedging Instrument | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	6,385	7,148
Designated as Hedging Instrument | Commodity Contracts | Other Assets
Derivative [Line Items]
Asset Derivatives at Fair Value	68	6
Designated as Hedging Instrument | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value		111
Designated as Hedging Instrument | Interest Rate Contracts
Derivative [Line Items]
Liability Derivatives at Fair Value		301
Designated as Hedging Instrument | Interest Rate Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value		160
Designated as Hedging Instrument | Interest Rate Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value		141
Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value	4,970	1,172
Liability Derivatives at Fair Value	846	571
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value	4,970	1,110
Liability Derivatives at Fair Value	771	571
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	158	1
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	4,749	1,110
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Other Assets
Derivative [Line Items]
Asset Derivatives at Fair Value	221
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	613	570
Derivatives Not Designated As Hedging Instruments | Foreign Currency Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value		$ 62
Derivatives Not Designated As Hedging Instruments | Foreign Currency Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	$ 75