Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Income Taxes [Line Items]
Interest and penalties	$ 0	$ 0
Effective tax rate	37.40%	37.30%	38.70%
Valuation allowance	$ 398	$ 254	$ 1,110
Undistributed Earnings of Foreign Subsidiaries	$ 7,574	$ 6,303	$ 1,833
United States federal jurisdiction
Income Taxes [Line Items]
Jurisdiction	years through fiscal 2011
State jurisdictions
Income Taxes [Line Items]
Jurisdiction	through fiscal 2004 and 2005