Other Changes in Plan Assets And Benefit Obligations Recognized in OCI (Detail) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (4,199)	$ (2,419)
Amortization of net loss	327	290
Total recognized in other comprehensive loss	(3,872)	(2,129)
Total recognized in net periodic benefit cost and other comprehensive loss	$ (3,618)	$ (1,881)