Income Taxes - Components of the Temporary Differences (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Deferred Tax Assets: [Abstract]
Postretirement benefits	$ 33,273	$ 31,100	$ 19,800
Accrued liabilities	11,760	10,091	6,156
Net operating loss carryforward	38,196	41,544	40,275
Intangible assets	71	594	1,126
Other	6,881	6,794	7,253
Total deferred tax assets	90,181	90,123	74,610
Deferred tax liabilities: [Abstract]
Unrealized gain on investments	(609)	(2,242)	0
Fixed assets	(5,370)	(2,647)	(1,902)
Other	(1,789)	(1,943)	(1,538)
Total deferred tax liabilities	(7,768)	(6,832)	(3,440)
Valuation allowance	(1,627)	(84,857)	(72,613)
Net deferred tax assets (liabilities)	$ 80,786
Net deferred tax assets (liabilities)		$ (1,566)	$ (1,443)