Components of Tax Provision (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Components Of Income Tax Expense Benefit [Line Items]
Current	$ 14,122	$ 20,176	$ 15,094
Deferred	5,089	(754)	(1,546)
Total provision for income tax	19,211	19,422	13,548
U.S. Federal
Components Of Income Tax Expense Benefit [Line Items]
Current	7,947	10,918	8,546
Deferred	4,873	379	(984)
Total provision for income tax	12,820	11,297	7,562
State and Local Jurisdiction
Components Of Income Tax Expense Benefit [Line Items]
Current	1,847	1,880	1,676
Deferred	236	62	24
Total provision for income tax	2,083	1,942	1,700
Foreign Jurisdictions
Components Of Income Tax Expense Benefit [Line Items]
Current	4,328	7,378	4,872
Deferred	(20)	(1,195)	(586)
Total provision for income tax	$ 4,308	$ 6,183	$ 4,286