Acquisitions (Schedule of Preliminary Allocation of Purchase Price) (Details)
$ in Thousands
9 Months Ended
Sep. 30, 2016
USD ($)
Acquisitions  
Purchase price $ 14,280
Prepaid expenses and other current assets 60
Mineral interests and mineral rights 19,413
Other non-current assets 460
Total assets 19,933
Deferred tax liability 5,615
Reclamation and remediation liabilities 38
Total liabilities 5,653
Net fair value $ 14,280