Investment (Income), Net (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013
Net Investment Income [Line Items]
Interest (income)	$ (1,404)	$ (1,503)
(Gain) on sale of marketable securities	(2,116)	(2,197)
Other-than-temporary impairment on securities		51
Dividend (income)	(283)	(245)
Investment (income), net	$ (3,803)	$ (3,894)