Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Retirement Benefits [Abstract]
Interest cost	$ 720	$ 781	$ 2,161	$ 2,343
Expected return on assets	(740)	(720)	(2,221)	(2,161)
Net periodic benefit cost	$ (20)	$ 61	$ (60)	$ 182