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, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Net periodic other postretirement benefit costs
Interest cost	$ 101	$ 153	$ 303	$ 460
Amortization of prior service credit	(69)	(22)	(207)	(68)
Recognition of actuarial loss	64	62	193	186
Net periodic other postretirement benefit cost	$ 96	$ 193	$ 289	$ 578