Schedule Of Financial Assets And Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2012	May 31, 2011
Fair Value [Line Items]
Assets	$ 1,157	$ 1,138
Liabilities	14,993	12,972
Derivative Contracts
Fair Value [Line Items]
Assets	1,157	1,138
Liabilities	14,993	12,972
Quoted Prices In Active Markets (Level 1)
Fair Value [Line Items]
Assets
Liabilities
Quoted Prices In Active Markets (Level 1) | Derivative Contracts
Fair Value [Line Items]
Assets
Liabilities
Significant Other Observable Inputs (Level 2)
Fair Value [Line Items]
Assets	1,157	1,138
Liabilities	14,993	12,972
Significant Other Observable Inputs (Level 2) | Derivative Contracts
Fair Value [Line Items]
Assets	1,157	1,138
Liabilities	14,993	12,972
Significant Unobservable Inputs (Level 3)
Fair Value [Line Items]
Assets
Liabilities
Significant Unobservable Inputs (Level 3) | Derivative Contracts
Fair Value [Line Items]
Assets
Liabilities