Basis of Presentation - Losses Recognized in Income for Derivative Instruments (Detail) (Foreign exchange forward contracts, Selling, general and administrative expenses, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013
Foreign exchange forward contracts | Selling, general and administrative expenses
Derivative Instruments, Gain (Loss) [Line Items]
Losses recognized in income for derivative instruments	$ 127	$ (87)