Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	May 31, 2016	May 31, 2015	May 31, 2014
Deferred tax assets:
Allowance for doubtful accounts	$ 130	$ 113
Deferred compensation and benefits	5,193	4,588
Net operating losses	681	398
Valuation allowance	(681)	(398)	$ (254)
Other	1,640	1,890
Net deferred tax asset	6,963	6,591
Deferred tax liabilities:
Accumulated depreciation	(41,392)	(42,505)
Deferred taxes on bargain purchase	(1,189)	(1,583)
Intangible asset	(158)	(155)
Net deferred tax liabilities	$ (35,776)	$ (37,652)