Annual report pursuant to Section 13 and 15(d)

BUSINESS AND OPERATIONS OF THE COMPANY (Details)

v3.8.0.1
BUSINESS AND OPERATIONS OF THE COMPANY (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]    
Total current assets $ 57,265 $ 55,947
Total assets 327,326 290,484
Deferred income tax liability, noncurrent 17,242 23,083
Total liabilities 142,315 126,108
Total liabilities and equity $ 327,326 290,484
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
Al Masane Al Kobra ("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%