SUPPLEMENTARY MINERAL RESERVE INFORMATION (UNAUDITED) (Ore Reserves) (Details) oz in Millions, lb in Millions, T in Millions	Dec. 31, 2020 lb oz g T
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	18,052
Copper
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	117,200
Copper | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	113,200
Copper | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	81,800
Gold
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	28.9
Gold | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	28.9
Gold | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	15.5
Molybdenum
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,770
Molybdenum | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,710
Molybdenum | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,390
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	4,300
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
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	14,300
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	200
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	2,591
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
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	15,200
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	0.2
Bagdad [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	920
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	777
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
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	5,700
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	3,240
Average ore grade of copper per metric ton	0.22%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0
Average ore grade of molybdenum per metric ton	0.02%
Sierrita [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	13,200
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	0.2
Sierrita [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	1,280
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	33
Average ore grade of copper per metric ton	0.27%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0
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	200
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	313
Average ore grade of copper per metric ton	0.44%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0003
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	2,500
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	0.2
Chino [Member] | Molybdenum | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
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
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	60
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
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	200
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	156
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
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	480
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	4,077
Average ore grade of copper per metric ton	0.36%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0
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	28,600
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	700
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	779
Average ore grade of copper per metric ton	0.41%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0
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	4,200
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
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	8
Average ore grade of copper per metric ton	0.55%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0047
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	100
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	0.1
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	53
Average ore grade of copper per metric ton	2.30%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0098
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	2,500
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	1.1
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] | 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	874
Average ore grade of copper per metric ton	1.08%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0073
Average ore grade of molybdenum per metric ton	0.00%
Grasberg block cave [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	17,500
Grasberg block cave [Member] | Gold | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	13.1
Grasberg block cave [Member] | Molybdenum | Productive Land [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	351
Average ore grade of copper per metric ton	0.92%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0090
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	6,000
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	6.0
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	439
Average ore grade of copper per metric ton	0.89%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0072
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	7,400
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	8.1
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