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