Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,505	$ 2,505
Accumulated Amortization	(1,879)	(1,761)
Customer relationships, Net Carrying Amount	215
Net Carrying Amount	626	744
Amortization of Intangible Assets	118	129	$ 164
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Customer Relationships, Gross Carrying Amount	2,094	2,094
Accumulated Amortization	(1,879)	(1,761)
Customer relationships, Net Carrying Amount	215	333	$ 462
Amortization of Intangible Assets	$ 118	$ 129
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