Taxes (Details) - Schedule of unrecognized tax benefits - USD ($) $ in Millions	12 Months Ended
May. 31, 2015	May. 31, 2014	May. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized benefits, Beginning of period	$ 14.4	$ 35.5	$ 38.7
Decreases related to prior year tax positions	(0.7)	(20.4)	(7.2)
Increase related to prior year tax positions	0.0	2.8	3.5
Increases related to current year tax positions	3.6	2.6	1.0
Settlements during the period	0.0	(1.8)	(0.5)
Lapse of statute of limitation	0.0	(4.3)	0.0
Gross unrecognized benefits, End of period	$ 17.3	$ 14.4	$ 35.5

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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