Amortization of Intangible Assets with Finite Useful Lives (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Feb. 28, 2013	May 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,505	2,505
Accumulated Amortization	(1,427)	(1,304)
Customer relationships, Net Carrying Amount	667
Net Carrying Amount	1,078	1,201
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Customer Relationships, Gross Carrying Amount	2,094	2,094
Accumulated Amortization	(1,427)	(1,304)
Customer relationships, Net Carrying Amount	667	790
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	3 years	3 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	8 years	8 years
Trade name
Finite-Lived Intangible Assets [Line Items]
Trade names, Gross Carrying Amount	411	411
Trade names, Net Carrying Amount	411	411