SUPPLEMENTARY MINERAL RESERVE INFORMATION (UNAUDITED) (Ore Reserves) (Details) oz in Millions, lb in Millions, T in Millions	Dec. 31, 2019 lb T oz g
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Amount of ore reserves (in metric tons of ore) | T	18,137
Copper
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	120,000
Copper | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	116,000
Copper | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	83,400
Gold
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	29.6
Gold | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	29.6
Gold | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	16.1
Molybdenum
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,640
Molybdenum | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,580
Molybdenum | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,250
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	4,435
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	14,500
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	190
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	2,535
Average ore grade of copper per metric ton	0.32%
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	15,300
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	790
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	812
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	5,900
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	2,960
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	0.02%
Sierrita [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	12,500
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	1,230
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	49
Average ore grade of copper per metric ton	0.25%
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	300
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	324
Average ore grade of copper per metric ton	0.45%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0003
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	2,700
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	0.3
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
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	67
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	220
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
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	490
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	4,265
Average ore grade of copper per metric ton	0.35%
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	29,300
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	710
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	717
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	3,900
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	29
Average ore grade of copper per metric ton	0.50%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0048
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	300
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	0.4
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	55
Average ore grade of copper per metric ton	2.33%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0097
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] | 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	959
Average ore grade of copper per metric ton	0.97%
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	17,200
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	14.2
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	340
Average ore grade of copper per metric ton	1.25%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0104
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	8,000
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	5.1
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	429
Average ore grade of copper per metric ton	0.92%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.0075
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	7,600
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	8.2
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