INCOME TAXES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Aug. 31, 2011	Aug. 31, 2010
Income Taxes [Line Items]
Effective income tax rate	29.80%	30.50%
Reduction in unrecognized tax benefits due to U.S. federal income tax examination settlement	$ 1.4
Current liabilities, potential payment of uncertain tax benefits	1.2
Unrecognized tax benefits	4.3
Unrecognized tax benefit which,if recognized, could affect the effective tax rate	3.4
Accrued tax interest and penalties accrued related to unrecognized tax benefits in income tax	$ 1.5

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties.

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