Property, Plant and Equipment, Net by Geographic Region (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2014	May 31, 2013
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 498,861	$ 459,430
UNITED STATES
Segment Reporting Information [Line Items]
Property, plant and equipment, net	429,068	400,032
Europe
Segment Reporting Information [Line Items]
Property, plant and equipment, net	56,884	51,222
Mexico
Segment Reporting Information [Line Items]
Property, plant and equipment, net	6,314
CANADA
Segment Reporting Information [Line Items]
Property, plant and equipment, net		1,275
Other Countries
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 6,595	$ 6,901