Fair Value (Schedule Of Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Feb. 29, 2012	May 31, 2011
Fair Value [Line Items]
Assets	$ 893	$ 1,138
Liabilities	12,056	12,972
Derivative Contracts [Member]
Fair Value [Line Items]
Assets	893	1,138
Liabilities	12,056	12,972
Quoted Prices In Active Markets (Level 1) [Member]
Fair Value [Line Items]
Assets
Liabilities
Quoted Prices In Active Markets (Level 1) [Member] | Derivative Contracts [Member]
Fair Value [Line Items]
Assets
Liabilities
Significant Other Observable Inputs (Level 2) [Member]
Fair Value [Line Items]
Assets	893	1,138
Liabilities	12,056	12,972
Significant Other Observable Inputs (Level 2) [Member] | Derivative Contracts [Member]
Fair Value [Line Items]
Assets	893	1,138
Liabilities	12,056	12,972
Significant Unobservable Inputs (Level 3) [Member]
Fair Value [Line Items]
Assets
Liabilities
Significant Unobservable Inputs (Level 3) [Member] | Derivative Contracts [Member]
Fair Value [Line Items]
Assets
Liabilities