Related Tax Effects Allocated to Each Component of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Components Of Other Comprehensive Income Loss [Line Items]
Foreign currency translation adjustments, Gross Amount	$ (15,822)	$ (1,613)	$ 1,070
Foreign currency translation adjustments, Tax Effect	2,559	1,213	130
Foreign currency translation adjustments, Net Amount	(13,263)	(400)	1,200
Foreign currency hedge, Gross Amount	3,237	(775)	(674)
Foreign currency hedge, Tax Effect	(904)	285	281
Foreign currency hedge, Net Amount	2,333	(490)	(393)
Other Comprehensive Income (Loss), before Tax, Total	(12,585)	(2,388)	396
Total other comprehensive income, Tax Effect	1,655	1,498	411
Total other comprehensive income, Net Amount	$ (10,930)	$ (890)	$ 807