Schedule of Financial Assets And Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2014		May 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 1,284		$ 761
Liabilities	4,879		9,774
Worthington Aritas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of additional interest acquired by the company	75.00%
Derivative Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,284	[1]	761	[1]
Liabilities	4,475	[1]	9,774	[1]
Contingent consideration obligation
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	404	[2]
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,284		761
Liabilities	4,475		9,774
Significant Other Observable Inputs (Level 2) | Derivative Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	1,284	[1]	761	[1]
Liabilities	4,475	[1]	9,774	[1]
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	404
Significant Unobservable Inputs (Level 3) | Contingent consideration obligation
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ 404	[2]

[1] The fair value of our derivative contracts is based on the present value of the expected future cash flows considering the risks involved, including non-performance risk, and using discount rates appropriate for the respective maturities. Market observable, Level 2 inputs are used to determine the present value of the expected future cash flows. Refer to "Note P - Derivative Instruments and Hedging Activities" for additional information regarding our use of derivative instruments.

[2] The fair value of the contingent consideration obligation related to our acquisition of a 75% interest in Worthington Aritas is determined using a Monte Carlo simulation model based on management's projections of future EBITDA levels. The fair value measurement is based on significant inputs not observable in the market and thus represents a Level 3 measurement. At each reporting date, we will revalue the contingent consideration obligation to estimated fair value and record changes in fair value as income or expense in our consolidated statement of earnings. Refer to "Note O - Acquisitions" for additional information.