Assets Measured at Fair Value on Non-recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2013		May 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on nonrecurring basis	$ 11,827		$ 6,856
Long-lived assets held and used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on nonrecurring basis	11,827	[1]	6,856	[2]
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on nonrecurring basis	11,827		6,856
Significant Other Observable Inputs (Level 2) | Long-lived assets held and used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on nonrecurring basis	$ 11,827	[1]	$ 6,856	[2]

[1] During the first quarter of fiscal 2014, we determined that certain indicators of impairment were present with regard to certain non-core Steel Processing assets. Recoverability of the identified asset group was tested using future cash flow projections based on management's estimate of market conditions. The sum of these undiscounted future cash flows was less than the net book value of the asset group. The net book value was also determined to be in excess of fair value and, accordingly, the asset group was written down to its fair value of $11,827,000, resulting in an impairment charge of $4,641,000. This impairment charge was recorded within impairment of long-lived assets in our consolidated statement of earnings. Fair value was determined based on market prices for similar assets.

[2] During the fourth quarter of fiscal 2013, the long-lived assets of our 60%-owned consolidated joint venture in India, WNCL, were written down to their fair value of $6,856,000, resulting in an impairment charge of $4,968,000. This impairment loss was recorded within impairment of long-lived assets in our consolidated statement of earnings. The portion of this impairment loss attributable to the noncontrolling interest, or $1,987,000, is recorded within net earnings attributable to noncontrolling interest in our consolidated statement of earnings. Fair value was determined based on market prices for similar assets.