Changes in Benefit Obligation (Detail) - Postretirement Benefits - USD ($) $ in Thousands	12 Months Ended
May 31, 2020	May 31, 2019	May 31, 2018
Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation at beginning of year	$ 4,990	$ 5,368
Interest cost	149	192	$ 173
Benefit payments	(1,659)	(287)
Actuarial (gains) losses	702	(283)
Benefit Obligation at End of Year	4,182	4,990	5,368
Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation at beginning of year	37,663	33,281
Service cost	1,661	1,507	1,307
Interest cost	1,089	1,122	939
Benefit payments	(639)	(664)
Actuarial (gains) losses	(683)	3,801
Currency exchange rate changes	(702)	(1,384)
Benefit Obligation at End of Year	$ 38,389	$ 37,663	$ 33,281

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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