XML 105 R68.htm IDEA: XBRL DOCUMENT v3.19.1
PROPERTY, PLANT AND EQUIPMENT - Rollforward (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance $ 658,629  
Impairment reversal   $ 24,357
Ending balance 701,175 658,629
Gross carrying amount    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 1,151,796 1,041,565
Additions 150,373 111,203
Disposals (16,792) (14,555)
Costs written off (9,998)  
Impairment reversal   24,357
Property write downs   (1,646)
Change in estimate of close down and restoration provision 3,269 (9,128)
Transfers 0 0
Ending balance 1,278,648 1,151,796
Accumulated depreciation and amortisation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance (493,167) (377,737)
Charge for the year (106,186) (127,254)
Disposals 12,728 11,824
Costs written off 9,152  
Ending balance (577,473) (493,167)
Plant and equipment    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 229,829  
Ending balance 283,729 229,829
Plant and equipment | Gross carrying amount    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 545,090 509,008
Additions 102,275 33,738
Disposals (15,485) (13,555)
Costs written off (9,998)  
Impairment reversal   24,357
Property write downs   0
Change in estimate of close down and restoration provision 0 (8,458)
Transfers 0 0
Ending balance 621,882 545,090
Plant and equipment | Accumulated depreciation and amortisation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance (315,261) (276,170)
Charge for the year (44,772) (50,915)
Disposals 12,728 11,824
Costs written off 9,152  
Ending balance (338,153) (315,261)
Mineral properties subject to depreciation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 215,367  
Ending balance 224,228 215,367
Mineral properties subject to depreciation | Gross carrying amount    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 393,273 306,277
Additions 33,371 43,118
Disposals 0 0
Costs written off 0  
Impairment reversal   0
Property write downs   (747)
Change in estimate of close down and restoration provision 3,269 (670)
Transfers 33,635 45,295
Ending balance 463,548 393,273
Mineral properties subject to depreciation | Accumulated depreciation and amortisation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance (177,906) (101,567)
Charge for the year (61,414) (76,339)
Disposals   0
Costs written off 0  
Ending balance (239,320) (177,906)
Mineral properties not yet subject to depreciation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 121,854  
Ending balance 101,990 121,854
Mineral properties not yet subject to depreciation | Gross carrying amount    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 121,854 133,560
Additions 13,771 33,589
Disposals 0 0
Costs written off 0  
Impairment reversal   0
Property write downs   0
Change in estimate of close down and restoration provision 0 0
Transfers (33,635) (45,295)
Ending balance 101,990 121,854
Mineral properties not yet subject to depreciation | Accumulated depreciation and amortisation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 0 0
Charge for the year 0 0
Disposals   0
Costs written off 0  
Ending balance 0 0
Exploration and evaluation assets    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 91,579  
Ending balance 91,228 91,579
Exploration and evaluation assets | Gross carrying amount    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 91,579 92,720
Additions 956 758
Disposals (1,307) (1,000)
Costs written off 0  
Impairment reversal   0
Property write downs   (899)
Change in estimate of close down and restoration provision 0 0
Transfers 0 0
Ending balance 91,228 91,579
Exploration and evaluation assets | Accumulated depreciation and amortisation    
Reconciliation of changes in property, plant and equipment [abstract]    
Beginning balance 0 0
Charge for the year 0 0
Disposals   0
Costs written off 0  
Ending balance $ 0 $ 0