Property, Plant and Mine Development – net - Summary of Property, Equipment and Mine Development (Details) - USD ($)
$ in Thousands |
9 Months Ended |
12 Months Ended |
|
Sep. 30, 2016 |
Dec. 31, 2015 |
Sep. 30, 2015 |
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
$ 96,625
|
$ 69,306
|
|
| Accumulated depreciation, depletion and amortization |
(25,666)
|
(17,669)
|
|
| Total property, equipment and mine development - net |
70,959
|
51,637
|
|
| Capital expenditures |
100
|
2,900
|
|
| Capital Lease Obligations [Member] |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Accumulated depreciation, depletion and amortization |
0
|
|
$ (500)
|
| Asset retirement costs |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
659
|
659
|
|
| Construction-in-progress |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
6,181
|
3,916
|
|
| Switchback Drilling Project [Member] |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
5,100
|
2,600
|
|
| Furniture and office equipment |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
1,569
|
1,555
|
|
| Land and mineral rights |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
230
|
230
|
|
| Light vehicles and other mobile equipment |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
1,821
|
1,887
|
|
| Machinery and equipment |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
20,073
|
19,867
|
|
| Capital lease |
0
|
3,100
|
|
| Mill facilities and infrastructure |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
8,990
|
8,920
|
|
| Mineral Interests And Mineral Rights |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
19,413
|
|
|
| Mine development |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
36,072
|
31,079
|
|
| Software and licenses [Member] |
|
|
|
| Property, equipment and mine development - net |
|
|
|
| Property and equipment, gross |
$ 1,617
|
$ 1,193
|
|