Pension and Other Postretirement Benefits - Components of Net Periodic Other Postretirement Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2020
Other postretirement benefit plans [Member]
Net periodic other postretirement benefit costs
Interest cost	$ 288	$ 307	$ 404
Amortization of prior service credit	(276)	(276)	(276)
Recognition of actuarial loss	297	307	257
Net Periodic Benefit (Income) Cost	309	338	385
Pension Plan [Member]
Net periodic other postretirement benefit costs
Service cost	1,117	1,685	1,796
Interest cost	22,532	23,188	27,320
Amortization of prior service credit	13	34	50
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	(2)	(7)	(115)
Recognition of actuarial loss	11,702	13,606	10,359
Net Periodic Benefit (Income) Cost	$ (15,990)	$ (12,336)	$ (14,208)