Commitments And Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Operating Leased Assets [Line Items]
Rental expenses	$ 1,197	$ 1,169	$ 1,125
Sale Revenue Percentage	66.80%	63.50%	66.80%
Maximum
Operating Leased Assets [Line Items]
Operating lease agreements Period	5 years