Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
New Accounting Pronouncements
Amount of recognized excess tax benefits as a reduction to income tax expense	$ (13.3)	$ 6.7	$ (9.1)	$ 12.2
Improvements to Employee Share-Based Payment Accounting
New Accounting Pronouncements
Amount of recognized excess tax benefits as a reduction to income tax expense	$ (0.4)		$ 1.6

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(b)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32639-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Income Tax Expense (or Benefit)
-URI http://asc.fasb.org/extlink&oid=6515339

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration