Income Tax - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	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]
Balance at the beginning of the year	$ 67,576	$ 53,763	$ 45,595
Additions based on income tax positions related to the current year	6,311	8,551	8,778
Additions for income tax positions of prior years	512	296	142
Foreign currency impact for income tax positions	(5,713)	5,303	(601)
Reductions for income tax positions of prior years	(32)	(60)	(151)
Settlements with income tax authorities	(504)	(277)	0
Changes in judgment regarding tax position	(65,591)	0	0
Balance at the end of the year	$ 2,559	$ 67,576	$ 53,763

Unrecognized Tax Benefits, Increase (Decreases) Resulting from Foreign Currency Translation

No definition available.

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- Definition

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

+ References

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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- Definition

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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- Definition

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 increase in unrecognized tax benefits resulting from settlements with taxing authorities.

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