PROPERTY, PLANT, EQUIPMENT AND MINING DEVELOPMENT COSTS, NET (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) $ / lb	Dec. 31, 2017 $ / lb	Dec. 31, 2016 $ / lb
Tyrone [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use | $	$ 37
Copper
Property, Plant and Equipment [Line Items]
Asset Impairment Evaluation, Average Price Assumption (Dollars per Pound)	3.00
Average Price	2.13	3.25	2.50
Molybdenum
Property, Plant and Equipment [Line Items]
Asset Impairment Evaluation, Average Price Assumption (Dollars per Pound)	10.00
Average Price	5.23	10.15	6.74
CME SWAPS MARKETS (COMEX) [Member] | Copper | Minimum
Property, Plant and Equipment [Line Items]
Asset Impairment Evaluation, Average Price Assumption (Dollars per Pound)	2.15
CME SWAPS MARKETS (COMEX) [Member] | Copper | Maximum
Property, Plant and Equipment [Line Items]
Asset Impairment Evaluation, Average Price Assumption (Dollars per Pound)	2.17
LONDON METAL EXCHANGE [Member] | Copper | Minimum
Property, Plant and Equipment [Line Items]
Asset Impairment Evaluation, Average Price Assumption (Dollars per Pound)	2.13
LONDON METAL EXCHANGE [Member] | Copper | Maximum
Property, Plant and Equipment [Line Items]
Asset Impairment Evaluation, Average Price Assumption (Dollars per Pound)	2.16