Quarterly report pursuant to Section 13 or 15(d)

GENERAL (Details)

v3.7.0.1
GENERAL (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2017
USD ($)
Segment
Dec. 31, 2016
USD ($)
Noncontrolling Interest [Line Items]    
Number of operating segments | Segment 2  
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]    
Total current assets $ 50,874 $ 55,947
Total assets 295,553 290,484
Deferred income tax liability, noncurrent 24,261 23,083
Total liabilities 129,057 126,108
Total liabilities and equity $ 295,553 290,484
Accounting Standards Update 2015-17 [Member]    
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]    
Deferred income tax asset, current   0
Total current assets   55,947
Total assets   290,484
Deferred income tax liability, noncurrent   23,083
Total liabilities   126,108
Total liabilities and equity   290,484
Accounting Standards Update 2015-17 [Member] | As Originally Reported [Member]    
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]    
Deferred income tax asset, current   1,615
Total current assets   57,562
Total assets   292,099
Deferred income tax liability, noncurrent   24,698
Total liabilities   127,723
Total liabilities and equity   $ 292,099
AMAK [Member]    
Noncontrolling Interest [Line Items]    
Percentage of ownership 33.00%  
Pioche Ely Valley Mines, Inc. ("PEVM") [Member]    
Noncontrolling Interest [Line Items]    
Percentage of ownership 55.00%