Components of Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Components Of Income Tax Expense Benefit [Line Items]
Current	$ 23,415	$ 17,265	$ 14,122
Deferred	(622)	(1,029)	5,089
Total provision for income tax	22,793	16,236	19,211
U.S. Federal
Components Of Income Tax Expense Benefit [Line Items]
Current	17,183	11,933	7,947
Deferred	606	358	4,873
Total provision for income tax	17,789	12,291	12,820
State and Local Jurisdiction
Components Of Income Tax Expense Benefit [Line Items]
Current	2,634	1,759	1,847
Deferred	(141)	319	236
Total provision for income tax	2,493	2,078	2,083
Foreign Jurisdictions
Components Of Income Tax Expense Benefit [Line Items]
Current	3,598	3,573	4,328
Deferred	(1,087)	(1,706)	(20)
Total provision for income tax	$ 2,511	$ 1,867	$ 4,308