Fair Value Measurements - Financial Instruments on a Recurring Basis (Details) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Nov. 30, 2014	May 31, 2014
Fair value on a recurring basis
Cash and cash equivalents	$ 826,724	$ 513,288
Total assets at fair value	826,724us-gaap_AssetsFairValueDisclosure	513,288us-gaap_AssetsFairValueDisclosure
Current accrued liabilities	274	286
Total liabilities at fair value	274	286
Level 1
Fair value on a recurring basis
Cash and cash equivalents	826,724	513,288
Total assets at fair value	826,724	513,288
Current accrued liabilities	0	0
Total liabilities at fair value	0	0
Level 2
Fair value on a recurring basis
Cash and cash equivalents	0	0
Total assets at fair value	0	0
Total liabilities at fair value	274	286
Level 3
Fair value on a recurring basis
Cash and cash equivalents	0	0
Total assets at fair value	0	0
Current accrued liabilities	0	0
Total liabilities at fair value	0	0
Foreign Exchange Forward \| Level 2
Fair value on a recurring basis
Current accrued liabilities	$ 274	$ 286

Fair value portion of trade and related party payables and accrued expenses.

No definition available.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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- Definition

Aggregation of the liabilities reported on the balance sheet measured at fair value on a recurring basis by the entity.

+ References

No definition available.

+ Details

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