Gains and 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, 2013	Feb. 29, 2012	Feb. 28, 2013	Feb. 29, 2012
Foreign exchange forward contracts | Selling, general and administrative expenses
Derivative Instruments, Gain (Loss) [Line Items]
Gains and losses recognized in income for derivative instruments	$ (64)	$ (29)	$ (454)	$ 212