Stock-Based Compensation Plans (Details 5) (Restricted Stock Unit [Member], USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
May 31, 2014	May 31, 2013	May 31, 2012
Restricted Stock Unit [Member]
RSUs, other information
Weighted-average grant-date fair value for RSUs granted	$ 36.37	$ 28.59	$ 27.67
Total intrinsic value of RSUs vested	$ 18.3	$ 15.5	$ 11.0
Total grant-date fair value of RSUs vested	$ 12.1	$ 13.4	$ 9.5

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Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options.

+ References

No definition available.

+ Details

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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