Summary of Tax Years Open to Examination by Major Tax Jurisdiction (Parenthetical) (Detail)	12 Months Ended
	May. 31, 2015
UNITED STATES | Federal
Income Tax Examination [Line Items]
Open tax years	2012
UNITED STATES | State and Local Jurisdiction
Income Tax Examination [Line Items]
Open tax years	2010
AUSTRIA
Income Tax Examination [Line Items]
Open tax years	2013
CANADA
Income Tax Examination [Line Items]
Open tax years	2011
Mexico
Income Tax Examination [Line Items]
Open tax years	2009