Financial Instruments (Unaudited) Not Designated as Hedging Instruments (Details)	Jun. 30, 2013 lb
Embedded derivatives in provisional sales contracts - Copper [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Open positions (in lbs except gold in oz)	428,000,000
Average contract price	3.32
Average market price	3.05
Maturities through	November 2013
Embedded derivatives in provisional sales contracts - Gold [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Open positions (in lbs except gold in oz)	39,000
Average contract price	1,409
Average market price	1,198
Maturities through	August 2013
Embedded derivatives in provisional purchase contracts - Copper [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Open positions (in lbs except gold in oz)	55,000,000
Average contract price	3.27
Average market price	3.06
Maturities through	November 2013
Atlantic Copper [Member] | Copper forward contracts [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Open positions (in lbs except gold in oz)	16,000,000
Average contract price	3.22
Maturities through	September 2013
Commodity Contract [Member] | Fair Value Hedging [Member] | Derivatives designated as hedging instruments [Member]
Derivative [Line Items]
Open positions (in lbs except gold in oz)	53,000,000
Average contract price	3.32
Maturities through	May 2014