Summary of Other Intangible Assets by Class (Detail) - USD ($) $ in Thousands	May. 31, 2015	May. 31, 2014
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, cost	$ 12,601	$ 12,601
Cost	166,664	181,499
Definite-lived intangible assets, cost	154,063	168,898
Accumulated Amortization	47,547	35,506
Trademarks
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, cost	12,601	12,601
Customer relationships
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	119,871	143,585
Accumulated Amortization	34,421	28,257
Non-compete agreements
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	14,221	10,733
Accumulated Amortization	6,897	4,263
Technology / know-how
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	15,633	12,068
Accumulated Amortization	2,350	1,273
Other Intangible Assets
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	4,338	2,512
Accumulated Amortization	$ 3,879	$ 1,713