Summary of Other Intangible Assets by Class (Detail) - USD ($) $ in Thousands	May 31, 2017	May 31, 2016
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, cost	$ 14,501	$ 14,501
Cost	145,915	145,696
Definite-lived intangible assets, cost	131,414	131,195
Accumulated Amortization	63,134	49,532
Trademarks
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, cost	14,501	14,501
Customer relationships
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	96,262	96,072
Accumulated Amortization	45,822	35,561
Non-compete agreements
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	9,443	9,422
Accumulated Amortization	7,751	6,237
Technology / know-how
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	21,755	21,689
Accumulated Amortization	5,607	3,865
Other Intangible Assets
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	3,954	4,012
Accumulated Amortization	$ 3,954	$ 3,869