Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Retirement Benefits [Abstract]
Interest cost	$ 512	$ 720	$ 1,537	$ 2,161
Expected return on assets	(731)	(740)	(2,193)	(2,221)
Amortization of net loss	56	0	167	0
Net periodic pension benefit	$ (163)	$ (20)	$ (489)	$ (60)