Financial Instruments (Unaudited) Not Designated as Hedging Instruments (Details)	Jun. 30, 2011 lb
Fair Value Hedging [Member] | FMC's copper futures and swap contracts [Member] | Derivatives designated as hedging instruments [Member]
Derivative [Line Items]
Derivative held (in lbs except gold in oz)	60,000,000
Average contract price	4.15
Maturities through	December 2012
Atlantic Copper's copper forward commodity contracts [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Derivative held (in lbs except gold in oz)	55,000,000
Average contract price	4.10
Maturities through	August 2011
Embedded derivatives in provisional sales contracts - Copper [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Derivative held (in lbs except gold in oz)	646,000,000
Average contract price	4.16
Average market price	4.27
Maturities through	December 2011
Embedded derivatives in provisional sales contracts - Gold [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Derivative held (in lbs except gold in oz)	163,000
Average contract price	1,522
Average market price	1,508
Maturities through	September 2011
Embedded derivatives in provisional purchase contracts - Copper [Member] | Derivatives not designated as hedging instruments [Member]
Derivative [Line Items]
Derivative held (in lbs except gold in oz)	196,000,000
Average contract price	4.14
Average market price	4.28
Maturities through	October 2011