Commitments And Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Operating Leased Assets [Line Items]
Rental expenses	$ 907	$ 1,197	$ 1,169
Sale Revenue Percentage	33.70%	66.80%	63.50%
Maximum
Operating Leased Assets [Line Items]
Operating lease agreements Period	5 years