Schedule Of Financial Assets And Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	May 31, 2012
Fair Value [Line Items]
Assets	$ 739	$ 1,157
Liabilities	12,370	14,993
Derivative Contracts
Fair Value [Line Items]
Assets	739	1,157
Liabilities	12,370	14,993
Significant Other Observable Inputs (Level 2)
Fair Value [Line Items]
Assets	739	1,157
Liabilities	12,370	14,993
Significant Other Observable Inputs (Level 2) | Derivative Contracts
Fair Value [Line Items]
Assets	739	1,157
Liabilities	$ 12,370	$ 14,993