Other Changes in Plan Assets And Benefit Obligations Recognized in OCI (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2014	May 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	$ (2,419)	$ 4,559
Amortization of prior service cost	290	439
Total recognized in other comprehensive income	(2,129)	4,998
Total recognized in net periodic benefit cost and other comprehensive income	$ (1,881)	$ 4,804