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		9 Months Ended
	Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015	Feb. 28, 2014
Foreign exchange forward contracts | Selling, general and administrative expenses
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) recognized in income for derivative instruments	$ 149	$ (32)	$ 659	$ (266)