Income Taxes - Components of the Temporary Differences (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Deferred Tax Assets: [Abstract]
Postretirement benefits	$ 31,100	$ 19,800	$ 26,014
Accrued liabilities	10,091	6,156	4,477
Net operating loss carryforward	41,544	40,275	44,607
Intangible assets	594	1,126	694
Other	6,794	7,253	8,945
Total deferred tax assets	90,123	74,610	84,737
Deferred Tax Liabilities, Unrealized Gains on Trading Securities	(2,242)	0	0
Deferred tax liabilities: [Abstract]
Fixed assets	(2,647)	(1,902)	(2,641)
Other	(1,943)	(1,538)	(882)
Total deferred tax liabilities	(6,832)	(3,440)	(3,523)
Valuation allowance	(84,857)	(72,613)	(82,522)
Net deferred tax liability	$ (1,566)	$ (1,443)	$ (1,308)