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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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New Accounting Pronouncements - Narrative (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Aug. 31, 2016	Aug. 31, 2015	May 31, 2016
New Accounting Pronouncement, Early Adoption [Line Items]
Increase in dilutive shares (shares)	2,631	1,632
Other Assets \| Accounting Standards Update 2015-03
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance costs			$ 5.6
Long Term Liabilities \| Accounting Standards Update 2015-03
New Accounting Pronouncement, Early Adoption [Line Items]
Debt issuance costs			$ (5.6)
New Accounting Pronouncement, Early Adoption, Effect \| Accounting Standards Update 2016-09
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease in income taxes	$ 17.2
Increase in dilutive shares (shares)	800
Stock based compensation expense	$ 1.7
New Accounting Pronouncement, Early Adoption, Effect \| Accounting Standards Update 2016-09 \| Additional Paid-in Capital
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect adjustment	(26.7)
New Accounting Pronouncement, Early Adoption, Effect \| Accounting Standards Update 2016-09 \| Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect adjustment	$ 26.7