Summary of Other Intangible Assets by Class (Detail) (USD $) In Thousands, unless otherwise specified	May 31, 2012	May 31, 2011
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, cost	$ 27,581	$ 850
Definite-lived intangible assets, cost	88,855	31,796
Accumulated Amortization	16,103	12,688
Cost	116,436	32,646
Patents and Trademarks
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	4,232	4,184
Accumulated Amortization	1,123	2,707
Customer Relationships
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	74,521	23,587
Accumulated Amortization	12,032	7,935
Non-compete Agreements
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	5,383	1,893
Accumulated Amortization	2,111	1,525
Other Intangible Assets
Other Intangible Assets [Line Items]
Definite-lived intangible assets, cost	4,719	2,132
Accumulated Amortization	837	521
Trademarks
Other Intangible Assets [Line Items]
Indefinite-lived intangible assets, cost	$ 27,581	$ 850