SUPPLEMENTARY MINERAL RESERVE INFORMATION (UNAUDITED) (Ore Reserves) (Details) oz in Millions, lb in Millions, T in Millions	Dec. 31, 2018 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	18,828
Copper
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	124,000
Copper | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	119,600
Copper | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	86,800
Gold
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	30.8
Gold | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	30.8
Gold | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	17.0
Molybdenum
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,830
Molybdenum | Consolidated Basis [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,780
Molybdenum | Net Equity Interest [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,440
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	4,619
Average ore grade of copper per metric ton	0.24%
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	15,600
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	180
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	2,426
Average ore grade of copper per metric ton	0.32%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
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	14,700
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	740
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	839
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%
Safford [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	6,200
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	3,369
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	0.02%
Sierrita [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	14,000
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	1,420
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	55
Average ore grade of copper per metric ton	0.25%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
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	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	395
Average ore grade of copper per metric ton	0.46%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.03
Average ore grade of molybdenum per metric ton	0.01%
Chino [Member] | Copper | Productive Land [Member]
Ore, average ore grades and recoverable proven and probable reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	3,400
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	0.3
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	0.00
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	71
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	168
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	520
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	4,324
Average ore grade of copper per metric ton	0.35%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.00
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	29,600
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	720
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	705
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%
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
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	5
Average ore grade of copper per metric ton	1.26%
Average ore grade of gold per metric ton (in grams per metric ton) | g	1.98
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	200
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	0.4
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	51
Average ore grade of copper per metric ton	0.50%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.57
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	500
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	0.8
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	57
Average ore grade of copper per metric ton	2.30%
Average ore grade of gold per metric ton (in grams per metric ton) | g	1.02
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	1.3
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	0.96%
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	17,200
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	14.1
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	349
Average ore grade of copper per metric ton	1.24%
Average ore grade of gold per metric ton (in grams per metric ton) | g	1.03
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	8,100
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	5.2
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	432
Average ore grade of copper per metric ton	0.92%
Average ore grade of gold per metric ton (in grams per metric ton) | g	0.76
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	7,600
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	8.4
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