Employee Pension Plans - Other Changes in Plan Assets And Benefit Obligations Recognized in OCI (Detail) - USD ($) $ in Thousands	12 Months Ended
May 31, 2018	May 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Net actuarial gain	$ 1,023	$ 2,926
Amortization of net loss	473	559
Total recognized in other comprehensive income	1,496	3,485
Total recognized in net periodic benefit cost and other comprehensive income	$ 1,355	$ 3,157

Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent.

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