Employee Pension Plans - Components of Net Periodic Pension Cost for the Defined Benefit Plan and Defined Contribution Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Compensation And Retirement Disclosure [Abstract]
Interest cost	$ 1,205	$ 1,352	$ 1,503
Return on plan assets	(4,289)	(1,928)	(532)
Net amortization and deferral costs	3,058	628	(918)
Net periodic pension cost (benefit) on defined benefit plan	(26)	52	53
Settlement cost	18		760
Defined contribution plans	17,562	16,495	16,308
Total retirement plan cost	$ 17,554	$ 16,547	$ 17,121