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Inventories, Including Long-Term Mill and Leach Stockpiles (Unaudited) (Details) - USD ($)
$ in Millions
Sep. 30, 2018
Dec. 31, 2017
Components of Inventories [Line Items]    
Total materials and supplies, net $ 1,439 $ 1,305
Mill stockpiles, current 287 360
Leach stockpiles, current 1,152 1,062
Total current mill and leach stockpiles 1,439 1,422
Raw materials (primarily concentrate) 299 265
Work-in-process 174 154
Finished goods 696 747
Total product inventories 1,169 1,166
Mill stockpiles, noncurrent 285 300
Leach stockpiles, noncurrent 1,070 1,109
Total long-term mill and leach stockpiles 1,355 1,409
Inventory obsolescence reserves $ 25 $ 29