Pension and Other Postretirement Benefits - Components of Net Periodic Other Postretirement Benefit Cost (Details) - Other postretirement benefit plans [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Net periodic other postretirement benefit costs
Interest cost	$ 76	$ 101	$ 230	$ 303
Amortization of prior service credit	(69)	(69)	(207)	(207)
Recognition of actuarial loss	77	64	230	193
Net periodic other postretirement benefit cost	$ 84	$ 96	$ 253	$ 289