Reconciliation of Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
	May 31, 2014	May 31, 2012
Income Tax Contingency [Line Items]
Beginning Balance	$ 3,705,000	$ 4,410,000
Increases - tax positions taken in prior years	609,000
Increases - current tax positions	635,000
Settlements	(346,000)
Lapse of statutes of limitations	(493,000)
Ending Balance	$ 4,110,000	$ 4,410,000