Pension and Post-retirement Benefits - Net Periodic Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	1,120	1,362	3,351	4,077
Expected return on plan assets	(1,115)	(1,305)	(3,336)	(3,908)
Amortization of net loss	13	9	40	28
Total	18	66	55	197
Post Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	21	18	64	55
Interest cost	51	60	154	180
Amortization of prior service credit	(134)	(134)	(403)	(403)
Amortization of net loss	41	20	124	62
Total	$ (21)	$ (36)	$ (61)	$ (106)