SUPPLEMENTARY MINERAL RESERVE INFORMATION (UNAUDITED) (Recoverable Reserves) (Details) oz in Millions, lb in Millions	Dec. 31, 2017 USD ($) lb oz
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated recoverable proven and probable copper reserves in leach stockpiles (in pounds)	2,100
Estimated recoverable proven and probable copper reserves in mill stockpiles (in pounds)	700
Copper
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	103,700
Long Term Average Price Used To Estimate Recoverable Reserves | $	$ 2.00
Gold (ounces) [Member]
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	34.2
Long Term Average Price Used To Estimate Recoverable Reserves | $	$ 1,000
Molybdenum mines
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,880
Long Term Average Price Used To Estimate Recoverable Reserves | $	$ 10
Silver
Estimated Recoverable Proven and Probable Reserves [Line Items]
Long Term Average Price Used To Estimate Recoverable Reserves | $	$ 15
Net Equity Interest [Member] | Copper
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	71,300
Net Equity Interest [Member] | Gold (ounces) [Member]
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	21.3
Net Equity Interest [Member] | Molybdenum mines
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,560
Net Equity Interest [Member] | Silver
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	218.2
Consolidated Basis [Member] | Copper
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	86,700
Consolidated Basis [Member] | Copper | North America
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	33,500
Consolidated Basis [Member] | Copper | South America
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	28,100
Consolidated Basis [Member] | Copper | Indonesia
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	25,100
Consolidated Basis [Member] | Gold (ounces) [Member]
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	23.5
Consolidated Basis [Member] | Gold (ounces) [Member] | North America
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.3
Consolidated Basis [Member] | Gold (ounces) [Member] | South America
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	0.0
Consolidated Basis [Member] | Gold (ounces) [Member] | Indonesia
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	23.2
Consolidated Basis [Member] | Molybdenum mines
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,840
Consolidated Basis [Member] | Molybdenum mines | North America
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	2,220
Consolidated Basis [Member] | Molybdenum mines | South America
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	620
Consolidated Basis [Member] | Molybdenum mines | Indonesia
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves	0
Consolidated Basis [Member] | Silver
Estimated Recoverable Proven and Probable Reserves [Line Items]
Estimated Recoverable Proven And Probable Reserves | oz	273.4