Pension and Post-retirement Benefits - Net Periodic Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	1,118	1,366	2,231	2,715
Expected return on plan assets	(1,113)	(1,309)	(2,221)	(2,603)
Amortization of net loss	14	9	27	19
Total	19	66	37	131
Post Retirement Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	22	19	43	37
Interest cost	52	60	103	120
Amortization of prior service credit	(135)	(135)	(269)	(269)
Amortization of net loss	41	21	83	42
Total	$ (20)	$ (35)	$ (40)	$ (70)