Derivatives & Risk Management - Summary of the Fair Value of the Derivative Instruments by Contract Type (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Feb. 29, 2016	May. 31, 2015
Prepaid and other current assets \| Foreign currency forward contracts
Derivative [Line Items]
Asset	$ 1,637	$ 697
Other non-current assets \| Foreign currency forward contracts
Derivative [Line Items]
Asset	321	54
Accrued liabilities \| Foreign currency forward contracts
Derivative [Line Items]
Liability	2,485	141
Accrued liabilities \| Variable cash settlement
Derivative [Line Items]
Liability	476	0
Other non-current liabilities \| Foreign currency forward contracts
Derivative [Line Items]
Liability	543	0
Other non-current liabilities \| Variable cash settlement
Derivative [Line Items]
Liability	$ 0	$ 20