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		6 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Net periodic other postretirement benefit costs
Interest cost	$ 101	$ 153	$ 202	$ 307
Amortization of prior service credit	(69)	(22)	(138)	(45)
Recognition of actuarial loss	64	62	128	124
Net periodic other postretirement benefit cost	$ 96	$ 193	$ 192	$ 386