Derivative Instruments and Hedging Activities - Schedule of Fair Value of Derivative Instruments (Detail) - USD ($) $ in Thousands	Feb. 29, 2020	May 31, 2019
Derivative [Line Items]
Asset Derivatives at Fair Value	$ 881	$ 2,414
Liability Derivatives at Fair Value	7,673	12,238
Derivatives Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value		5
Liability Derivatives at Fair Value	3,827	8,584
Derivatives Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	3,230	8,383
Derivatives Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value		5
Derivatives Designated As Hedging Instruments | Commodity Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	597	201
Derivatives Not Designated As Hedging Instruments
Derivative [Line Items]
Asset Derivatives at Fair Value	881	2,409
Liability Derivatives at Fair Value	3,846	3,654
Derivatives Not Designated As Hedging Instruments | Commodity Contracts
Derivative [Line Items]
Asset Derivatives at Fair Value	881	2,409
Liability Derivatives at Fair Value	3,839	3,634
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	3,596	3,568
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Receivables
Derivative [Line Items]
Asset Derivatives at Fair Value	881	2,347
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Other Assets
Derivative [Line Items]
Asset Derivatives at Fair Value		62
Derivatives Not Designated As Hedging Instruments | Commodity Contracts | Other Liabilities
Derivative [Line Items]
Liability Derivatives at Fair Value	243	66
Derivatives Not Designated As Hedging Instruments | Foreign Currency Exchange Contracts | Accounts Payable
Derivative [Line Items]
Liability Derivatives at Fair Value	$ 7	$ 20