Summary of Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2014
Goodwill [Line Items]
Balance at May 31, 2013	$ 103,466
Acquisitions	11,336
Foreign currency adjustments	(688)
Balance at February 28, 2014	114,114
MS Segment
Goodwill [Line Items]
Balance at May 31, 2013	19,130
Foreign currency adjustments	611
Balance at February 28, 2014	19,741
IHT Segment
Goodwill [Line Items]
Balance at May 31, 2013	53,800
Acquisitions	11,336
Foreign currency adjustments	(1,448)
Balance at February 28, 2014	63,688
Quest Segment
Goodwill [Line Items]
Balance at May 31, 2013	30,536
Foreign currency adjustments	149
Balance at February 28, 2014	$ 30,685