Fair Value Measurements and Derivative Instruments - Outstanding Futures Contracts (Detail) (Designated as Hedging Instrument [Member], Commodity Contract [Member])
May 31, 2014
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Corn futures [Member]
 
Derivative [Line Items]  
Outstanding futures contracts 4,775,000
Ethanol futures [Member]
 
Derivative [Line Items]  
Outstanding futures contracts 14,700,000
Natural gas futures [Member]
 
Derivative [Line Items]  
Outstanding futures contracts 40,000