Components of Net Postretirement Expense (Detail) - Postretirement Benefits - USD ($) $ in Thousands	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost on the accumulated obligation	$ 74	$ 149	$ 192
Prior service (credit)	(167)	(219)	(219)
Net actuarial (gains) losses	42	(66)	(26)
Net Pension Cost	(51)	(136)	(53)
Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost - benefits earned during the period	1,959	1,661	1,507
Interest cost on the accumulated obligation	1,286	1,089	1,122
Net actuarial (gains) losses	590	611	442
Net Pension Cost	$ 3,835	$ 3,361	$ 3,071