Pension and Other Postretirement Benefits - Components of Net Periodic Other Postretirement Benefit Cost (Details) - Other postretirement benefit plans [Member] - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Net periodic other postretirement benefit costs
Interest cost	$ 404	$ 613	$ 629
Amortization of prior service credit	(276)	(90)	(22)
Recognition of actuarial loss	257	248	280
Net Periodic Benefit (Income) Cost	$ 385	$ 771	$ 887