Derivative Instruments and Hedging Activities - Schedule of Fair Value of Derivative Instruments (Detail) - USD ($) $ in Thousands	Nov. 30, 2018	May 31, 2018
Derivative [Line Items]
Asset Derivatives at Fair Value	$ 982	$ 11,423
Liability Derivatives at Fair Value	2,998	846
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value		6,453
Liability Derivatives at Fair Value	1,645
Derivatives Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	1,560
Derivatives Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value		6,385
Derivatives Designated As Hedging Instruments | Commodity Contracts | Other Assets
Derivative [Line Items]
Asset Derivatives at Fair Value		68
Derivatives Designated As Hedging Instruments | Commodity Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	85
Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value	982	4,970
Liability Derivatives at Fair Value	1,353	846
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value	982	4,970
Liability Derivatives at Fair Value	1,317	771
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	1,167	613
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	890	4,749
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Other Assets
Derivative [Line Items]
Asset Derivatives at Fair Value	92	221
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	150	158
Derivatives Not Designated As Hedging Instruments | Foreign Currency Exchange Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	$ 36	$ 75