SUPPLEMENTARY MINERAL RESERVE INFORMATION (UNAUDITED) (Ore Reserves) (Details) oz in Millions, lb in Millions, T in Millions	Dec. 31, 2017 lb oz T g
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	13,867
Copper
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	103,700
Copper | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	86,700
Copper | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	71,300
Gold
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	34.2
Gold | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	23.5
Gold | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	21.3
Molybdenum
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,880
Molybdenum | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,840
Molybdenum | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,560
Morenci | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	3,134
Average ore grade of copper per metric ton	0.26%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.00%
Morenci | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	11,800
Morenci | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Morenci | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	140
Bagdad [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	1,405
Average ore grade of copper per metric ton	0.31%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.02%
Bagdad [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	7,500
Bagdad [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.1
Bagdad [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	360
Safford [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	662
Average ore grade of copper per metric ton	0.45%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.00%
Safford [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	5,000
Safford [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Safford [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Sierrita [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	2,245
Average ore grade of copper per metric ton	0.23%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.03%
Sierrita [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	9,900
Sierrita [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.1
Sierrita [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	1,010
Tyrone [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	9
Average ore grade of copper per metric ton	0.42%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.00%
Tyrone [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	100
Tyrone [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Tyrone [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Chino [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	276
Average ore grade of copper per metric ton	0.46%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.02
Average ore grade of molybdenum per metric ton	0.00%
Chino [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,400
Chino [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.1
Chino [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	10
Miami [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	0
Average ore grade of copper per metric ton	0.00%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.00%
Miami [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	100
Miami [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Miami [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Henderson [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	74
Average ore grade of copper per metric ton	0.00%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.17%
Henderson [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Henderson [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Henderson [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	240
Climax [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	160
Average ore grade of copper per metric ton	0.00%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.15%
Climax [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Climax [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Climax [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	500
Cerro Verde | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	3,577
Average ore grade of copper per metric ton	0.37%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.01%
Cerro Verde | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	25,600
Cerro Verde | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Cerro Verde | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	620
El Abra | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	394
Average ore grade of copper per metric ton	0.44%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
Average ore grade of molybdenum per metric ton	0.00%
El Abra | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,500
El Abra | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
El Abra | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Grasberg open pit [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	34
Average ore grade of copper per metric ton	1.29%
Average ore grade of gold per metric ton (in grams per metric ton) | g	2.64
Average ore grade of molybdenum per metric ton	0.00%
Grasberg open pit [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	1,100
Grasberg open pit [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	2.7
Grasberg open pit [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Deep Ore Zone [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	79
Average ore grade of copper per metric ton	0.54%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.76
Average ore grade of molybdenum per metric ton	0.00%
Deep Ore Zone [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	900
Deep Ore Zone [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	1.6
Deep Ore Zone [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Big Gossan [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	58
Average ore grade of copper per metric ton	2.22%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.93
Average ore grade of molybdenum per metric ton	0.00%
Big Gossan [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,600
Big Gossan [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	1.2
Big Gossan [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Grasberg block cave [Member] | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	963
Average ore grade of copper per metric ton	1.01%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.72
Average ore grade of molybdenum per metric ton	0.00%
Grasberg block cave [Member] | Copper | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	18,100
Grasberg block cave [Member] | Gold | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	14.5
Grasberg block cave [Member] | Molybdenum | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Kucing Liar [Member] | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	360
Average ore grade of copper per metric ton	1.25%
Average ore grade of gold per metric ton (in grams per metric ton) | g	1.07
Average ore grade of molybdenum per metric ton	0.00%
Kucing Liar [Member] | Copper | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	8,400
Kucing Liar [Member] | Gold | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	5.4
Kucing Liar [Member] | Molybdenum | Undeveloped [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Deep Mill Level Zone [Member] | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	437
Average ore grade of copper per metric ton	0.91%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.76
Average ore grade of molybdenum per metric ton	0.00%
Deep Mill Level Zone [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	7,700
Deep Mill Level Zone [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	8.5
Deep Mill Level Zone [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0