Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Current
Federal	$ 11,636	$ 18,007	$ 17,007
State	1,355	1,720	1,417
Foreign	387	319	573
Deferred
Federal	(3,626)	(7,553)	(4,401)
State	(248)	(500)	257
Foreign	(286)	125	(494)
Provision for income taxes	$ 9,218	$ 12,118	$ 14,359