FAIR VALUE MEASUREMENT (Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Time Deposits, at Carrying Value		$ 19
Cash equivalents: [Abstract]
Money market funds	4,007	3,584
Trust assets (current and long-term): [Abstract]
U.S. core fixed income fund	46	42
Government mortgage-backed securities	47	35
Corporate bonds	19	23
Asset-backed securities	9	22
Government bonds and notes	21	10
Money market funds	9	15
Municipal bonds	1	1
Total trust assets	152	148
Available-for-sale securities: [Abstract]
Equity securities	9	9	[1]
Money market funds	2	6	[1]
Total available-for-sale securities	11	15	[1]
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	72	357	[2]
Copper futures and swap contracts	3	18
Copper forward contracts	2
Total derivative assets	77	375
Total assets	4,247	4,122
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	(82)	(115)	[2]
Copper Futures And Swap Contracts	(13)
Copper forward contracts		(10)
Total derivative liabilities	(95)	(125)
Level 1 [Member]
Cash equivalents: [Abstract]
Money market funds	4,007	3,584
Trust assets (current and long-term): [Abstract]
U.S. core fixed income fund	0	0
Government mortgage-backed securities	0	0
Corporate bonds	0	0
Asset-backed securities	0	0
Government bonds and notes	0	0
Money market funds	9	15
Municipal bonds	0	0
Total trust assets	9	15
Available-for-sale securities: [Abstract]
Equity securities	9	9	[1]
Money market funds	2	6	[1]
Total available-for-sale securities	11	15	[1]
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	0	0	[2]
Copper futures and swap contracts	3	18
Copper forward contracts	1
Total derivative assets	4	18
Total assets	4,031	3,632
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	0	0	[2]
Copper Futures And Swap Contracts	(11)
Copper forward contracts		(1)
Total derivative liabilities	(11)	(1)
Level 2 [Member]
Cash equivalents: [Abstract]
Money market funds	0	0
Trust assets (current and long-term): [Abstract]
U.S. core fixed income fund	46	42
Government mortgage-backed securities	47	35
Corporate bonds	19	23
Asset-backed securities	9	22
Government bonds and notes	21	10
Money market funds	0	0
Municipal bonds	1	1
Total trust assets	143	133
Available-for-sale securities: [Abstract]
Equity securities	0	0	[1]
Money market funds	0	0	[1]
Total available-for-sale securities	0	0	[1]
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	72	357	[2]
Copper futures and swap contracts	0	0
Copper forward contracts	1
Total derivative assets	73	357
Total assets	216	490
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	(82)	(115)	[2]
Copper Futures And Swap Contracts	(2)
Copper forward contracts		(9)
Total derivative liabilities	(84)	(124)
Level 3 [Member]
Cash equivalents: [Abstract]
Money market funds	0	0
Trust assets (current and long-term): [Abstract]
U.S. core fixed income fund	0	0
Government mortgage-backed securities	0	0
Corporate bonds	0	0
Asset-backed securities	0	0
Government bonds and notes	0	0
Money market funds	0	0
Municipal bonds	0	0
Total trust assets	0	0
Available-for-sale securities: [Abstract]
Equity securities	0	0	[1]
Money market funds	0	0	[1]
Total available-for-sale securities	0	0	[1]
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	0	0	[2]
Copper futures and swap contracts	0	0
Copper forward contracts	0
Total derivative assets	0	0
Total assets	0	0
Derivatives: [Abstract]
Embedded derivatives in provisional sales/purchases contracts	0	0	[2]
Copper Futures And Swap Contracts	0
Copper forward contracts		0
Total derivative liabilities	$ 0	$ 0

[1] Excluded were $19 million of time deposits.

[2] At the end of 2011, FCX reevaluated its level determination for its embedded derivatives in provisional sales/purchases contracts, including those reported at December 31, 2010. Although the critical input in these measurements are quoted market prices for copper, gold and molybdenum, the contracts themselves are not traded on an exchange and, therefore, are more appropriately classified within Level 2 of the fair value hierarchy.