Commitments and Contingencies - Contractual Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Jun. 30, 2016
Capital Lease Obligations
2017	$ 341
2018	990
2019	186
2020	51
2021	4
Thereafter	0
Total minimum lease payments	1,572
Less: imputed interest (0.82% to 10.7%)	(52)
Present value of future minimum lease payments	1,520
Less: current portion	1,131	$ 1,323
Other long-term liabilities-capital leases	389	$ 1,036
Operating Lease Obligations
2017	1,233
2018	4,684
2019	3,798
2020	2,133
2021	798
Thereafter	186
Future Minimum Payments Due	12,832
Purchase Commitments
2017	41,919
2018	37,584
2019	0
2020	0
2021	0
Thereafter	0
Future minimum purchase commitments	$ 79,503
Minimum
Purchase Commitments
Imputed interest rate on capital leases	0.82%
Maximum
Purchase Commitments
Imputed interest rate on capital leases	10.70%
Pension Plan
Defined Benefit Plan Obligations
2017	$ 1,973
2018	8,304
2019	8,554
2020	8,844
2021	9,074
Thereafter	47,262
Future payments due	84,011
Other Postretirement Benefit Plan
Defined Benefit Plan Obligations
2017	270
2018	1,102
2019	1,143
2020	1,176
2021	1,210
Thereafter	6,246
Future payments due	11,147
Revolving Credit Facility
Revolving Credit Facility
2017	44,175
2018	0
2019	0
2020	0
2021	0
Thereafter	0
Future minimum debt maturities	44,175
New Facility Construction and Equipment Costs [Member]
Purchase Commitments
2017	11,698
2018	0
2019	0
2020	0
2021	0
Thereafter	0
Future minimum purchase commitments	11,698
Texas Facility Construction Contract [Member]
Purchase Commitments
2017	5,500
Texas Facility Equipment Contract [Member]
Purchase Commitments
2017	$ 6,200