Summary of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified						12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2013 Customer relationships	May 31, 2012 Customer relationships	May 31, 2011 Customer relationships	May 31, 2013 Customer relationships Minimum	May 31, 2012 Customer relationships Minimum	May 31, 2013 Customer relationships Maximum	May 31, 2012 Customer relationships Maximum	May 31, 2013 Trade name	May 31, 2012 Trade name
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life						3 years	3 years	8 years	8 years
Customer Relationships, Gross Carrying Amount			$ 2,094	$ 2,094
Gross Carrying Amount	2,505	2,505
Trade names, Gross Carrying Amount										411	411
Accumulated Amortization	(1,468)	(1,304)	(1,468)	(1,304)
Trade names, Net Carrying Amount										411	411
Customer relationships, Net Carrying Amount	626		626	790	803
Net Carrying Amount	$ 1,037	$ 1,201