Consolidated Condensed Statements of Comprehensive Income (Unaudited) (Parenthetical) (Less Than [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Aug. 31, 2012	Aug. 31, 2011
Less Than [Member]
Change in fair value of derivative, tax expense (benefit)	$ 0.1	$ (0.1)
Change in fair value of available-for-sale securities, tax expense (benefit)	$ 0.1	$ (0.1)

Tax effect of the gross appreciation or the gross loss, net of reclassification adjustment, in the value of the total unsold available-for-sale securities at the end of an accounting period.

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Total tax effect of the change in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. The change includes an entity's share of an equity investee's increase or decrease in deferred hedging gains or losses. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

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