Commitments and Contingencies (Amount Borrowed) (Details) - Revolving Credit Facility [Member] - USD ($) $ in Millions	12 Months Ended
May 31, 2016	May 31, 2015
Line of Credit Facility [Line Items]
Number of days borrowed	5 days	2 days
Maximum amount borrowed	$ 450.0	$ 150.0
Average amount borrowed	$ 305.0	$ 125.0
Weighted-average interest rate	3.39%	3.25%

The effective interest rate during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration