Income Taxes - Components of the Temporary Differences (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Deferred Tax Assets: [Abstract]
Postretirement benefits	$ 20,232	$ 20,775
Accrued liabilities	3,970	5,042
Net operating loss carryforward	38,754	37,768
Deferred Tax Assets, Goodwill and Intangible Assets	9,482	0
Operating lease liabilities	5,419
Other	6,893	5,950
Total deferred tax assets	84,750	69,535
Deferred tax liabilities: [Abstract]
Fixed assets	(13,427)	(15,562)
Right-of-use operating lease assets	5,513
Other	(2,950)	(3,749)
Total deferred tax liabilities	(21,890)	(19,311)
Valuation allowance	(64,354)	(52,019)	$ (1,900)
Deferred Tax Liabilities, Net	$ (1,494)	$ (1,795)