Property, Plant and Equipment, Net by Geographic Region (Detail) - USD ($) $ in Thousands	May. 31, 2015	May. 31, 2014
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 513,190	$ 498,861
UNITED STATES
Segment Reporting Information [Line Items]
Property, plant and equipment, net	439,296	429,068
Europe
Segment Reporting Information [Line Items]
Property, plant and equipment, net	50,520	56,884
Mexico
Segment Reporting Information [Line Items]
Property, plant and equipment, net	5,030	6,314
CANADA
Segment Reporting Information [Line Items]
Property, plant and equipment, net	4,284
Other Countries
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 14,060	$ 6,595