Derivatives and Hedging (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2017	May 31, 2016
Derivative [Line Items]
Unrealized gain (loss) on foreign currency derivatives	$ (0.8)	$ 0.5
Not Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 36.5	$ 31.8