Changes in Benefit Obligation (Detail) - Postretirement Benefits - USD ($) $ in Thousands	12 Months Ended
May 31, 2019	May 31, 2018	May 31, 2017
Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation at beginning of year	$ 5,368	$ 5,892
Interest cost	192	173	$ 229
Benefit payments	(287)	(297)
Actuarial (gains) losses	(283)	(400)
Benefit Obligation at End of Year	4,990	5,368	5,892
Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation at beginning of year	33,281	27,868
Service cost	1,507	1,307	1,097
Interest cost	1,122	939	854
Benefit payments	(664)	(604)
Actuarial (gains) losses	3,801	2,638
Currency exchange rate changes	(1,384)	1,133
Benefit Obligation at End of Year	$ 37,663	$ 33,281	$ 27,868

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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