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New Accounting Pronouncements - Narrative (Details) - USD ($) $ in Millions | Feb. 28, 2017 | May 31, 2016
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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 |
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)

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