Schedule of Acquisition of Intangible Assets (Detail) (MEF, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2014
Business Acquisition [Line Items]
Total acquired identifiable intangible assets	$ 13,600
Technological know-how
Business Acquisition [Line Items]
Acquired finite lived intangible assets	5,100
Useful Life (Years)	10 years
Customer relationships
Business Acquisition [Line Items]
Acquired finite lived intangible assets	4,300
Useful Life (Years)	7 years
Non-compete agreements
Business Acquisition [Line Items]
Acquired finite lived intangible assets	2,400
Useful Life (Years)	4 years
Backlog
Business Acquisition [Line Items]
Acquired finite lived intangible assets	$ 1,800
Backlog | Maximum
Business Acquisition [Line Items]
Useful Life (Years)	1 year