EMPLOYEE BENEFITS (Schedule of Disclosures) (Details) In Millions, unless otherwise specified	12 Months Ended															12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2011 Pension plan [Member] USD ($)	Dec. 31, 2010 Pension plan [Member] USD ($)	Dec. 31, 2011 Pension plan [Member] Postretirement Medical And Life Insurance [Member] USD ($)	Dec. 31, 2010 Pension plan [Member] Postretirement Medical And Life Insurance [Member] USD ($)	Dec. 31, 2009 Pension plan [Member] Postretirement Medical And Life Insurance [Member] USD ($)	Dec. 31, 2011 Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member] USD ($)		Dec. 31, 2010 Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member] USD ($)		Dec. 31, 2009 Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member] USD ($)	Dec. 31, 2011 Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member] IDR	Dec. 31, 2010 Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member] IDR	Dec. 31, 2011 Pension plan [Member] Atlantic Copper [Member] USD ($)		Dec. 31, 2010 Pension plan [Member] Atlantic Copper [Member] USD ($)		Dec. 31, 2009 Pension plan [Member] Atlantic Copper [Member] USD ($)	Dec. 31, 2011 Pension plan [Member] FCX [Member] USD ($)		Dec. 31, 2010 Pension plan [Member] FCX [Member] USD ($)		Dec. 31, 2009 Pension plan [Member] FCX [Member] USD ($)	Dec. 31, 2011 Pension plan [Member] FCX [Member] FCX SERP Plan [Member]	Dec. 31, 2010 Pension plan [Member] FCX [Member] FCX SERP Plan [Member]	Dec. 31, 2009 Pension plan [Member] FCX [Member] FCX SERP Plan [Member]	Dec. 31, 2011 Pension plan [Member] FCX [Member] FMC Plans [Member]		Dec. 31, 2010 Pension plan [Member] FCX [Member] FMC Plans [Member]		Dec. 31, 2009 Pension plan [Member] FCX [Member] FMC Plans [Member]		Dec. 31, 2011 Pension plan [Member] Postretirement Medical Insurance [Member] USD ($)	Dec. 31, 2010 Pension plan [Member] Postretirement Medical Insurance [Member]	Dec. 31, 2011 Other Benefits [Member] USD ($)	Dec. 31, 2010 Other Benefits [Member] USD ($)	Dec. 31, 2011 Minimum [Member] Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member]	Dec. 31, 2011 Maximum [Member] Pension plan [Member] Investment In Subsidiary Pt Freeport Indonesia [Member]
Schedule of disclosures of defined benefit plans [Line Items]
Exchange Rate Of Rupiah To Dollars														9,060	8,990
Defined benefit plan, expected return on plan assets (in hundredths)	7.50%								8.50%
Change in benefit obligation [Roll Forward]
Benefit obligation at beginning of year						$ 240	$ 265		$ 135		$ 80					$ 71		$ 79			$ 1,598		$ 1,472
Service cost						1	1	1	13		8		5			0		0			24		26		26
Interest cost						11	13	15	11		8		7			3		3		4	83		82		85
Actuarial losses (gains)						(7)	(13)		55		41					0		0			172		104
Foreign exchange losses (gains)									(1)		4					(1)		(4)			(1)		(1)
Benefits paid						(37)	(41)		(7)		(6)					(8)		(7)			(85)		(85)
Defined Benefit Plan Benefits Paid Net Of Employee And Partner Contributions and Medicare Part D Subsidy						(22)	(26)
Curtailments and special retirement benefits						0	0	(1)													0		0		(4)
Benefits obligation at end of year						223	240	265	206		135		80			65		71		79	1,791		1,598		1,472
Change in plan assets [Roll Forward]
Fair value of plan assets at beginning of year						0	0		97		78					23		21			1,112		1,067
Actual return on plan assets									9		13					0		0			88		126
Employer contributions						25	30		9	[1]	8	[1]				11	[1]	9	[1]		26	[1]	5	[1]
Employee contributions						12	11
Foreign exchange gains (losses)									(1)		4					0		0			0		(1)
Benefits paid						(37)	(41)		(7)		(6)					(8)		(7)			(85)		(85)
Fair value of plan assets at end of year						0	0	0	107		97		78			26		23		21	1,141		1,112		1,067
Funded status at end of year						(223)	(240)		(99)		(38)					(39)		(48)			(650)		(486)
Accumulated benefit obligation									115		68					65		71			1,701		1,517
Weighted-average assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)						4.20%	4.90%		7.00%	[2]	8.50%	[2]				6.77%	[2]	6.77%	[2]		4.60%	[2]	5.40%	[2]
Rate of compensation increase (in hundredths)									8.00%	[3]	8.00%	[3]									3.75%	[3]	3.75%	[3]															10.00%	13.00%
Balance sheet classification of funded status: [Abstract]
Other assets									0		0					0		0			6		6
Accounts payable and accrued liabilities						(23)	(26)		0		0					0		0			(4)		(4)														(7)	(8)
Other liabilities						(200)	(214)		(99)		(38)					(39)		(48)			(652)		(488)														(57)	(53)
Total						(223)	(240)		(99)		(38)					(39)		(48)			(650)		(486)
Estimated future employer contributions in next fiscal year									14							9					97
Number of years Mercer Pension Discount Curve consists of spot interest rates at half-year increments																													30 years
Years of service required for annuity to equal percentage of executive's highest average compensation for any consecutive three-year period during the preceeding five years before retirement																										25 years
Weighted-average assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)						4.90%	5.20%	6.30%	8.50%		10.50%		12.00%			6.77%		6.77%		6.77%						4.00%	4.00%	4.00%	5.40%		5.80%		6.10%
Expected return on plan assets (in hundredths)									9.25%		8.25%		10.00%																8.00%	[4]	8.50%	[4]	8.50%	[4]
Rate of compensation increase (in hundredths)									8.00%		8.00%		8.00%																3.75%	[4]	4.25%	[4]	4.25%	[4]
Components of net periodic benefit (income) cost and other amounts recognized in other comprehensive income [Abstract]
Service cost						1	1	1	13		8		5			0		0			24		26		26
Interest cost						11	13	15	11		8		7			3		3		4	83		82		85
Benefits paid						(37)	(41)		(7)		(6)					(8)		(7)			(85)		(85)
Expected return on plan assets									(9)		(7)		(5)								(86)		(87)		(73)
Amortization of prior service cost									1		1		1								(1)		(1)		0
Amortization of net actuarial losses									3		0		1			1		1		1	19		22		26
Curtailments and special retirement benefits						0	0	(1)													0		0		(4)
Net periodic benefit cost						12	14	15	19		10		9			4		4		5	39		42		60
Amounts recognized in other comprehensive loss (income) [Abstract]
Prior service (credit) cost				2	2
Prior service (credit) cost, net of tax				1	1
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax				642	440	4	3
Actuarial net loss (gain), net of tax	(157)	(69)	9	390	267	3	2
Estimated prior service (credit) cost in next fiscal year				1
Estimated actuarial net loss (gain) in next fiscal year				40
Estimated actuarial net loss (gain) in next fiscal year, net of tax				25
Assumed health care cost trend rates abstract
Health care cost trend rates for the next fiscal year (in hundreds)																																			8.00%	8.25%
Ultimate health care cost trend rate (in hundreds)																																			4.50%	4.75%
Year that rate reaches ultimate trend rate																																			2026	2025
Effect of a one-percentage point change in assumed health care cost trend rates [Abstract]
Effect of a one-percentage point increase on service and interest cost components																																			1
Effect of a one-percentage point decrease on service and interest cost components																																			1
Effect of a one-percentage point increase on post-retirement benefit obligation																																			8
Effect of a one-percentage point decrease on post-retirement benefit obligation																																			7
Expected cash flows for benefit plans [Abstract]
2012						23			16	[5]						7	[6]				88
2013						21			11	[5]						7	[6]				88
2014						20			11	[5]						7	[6]				90
2015						19			13	[5]						7	[6]				91
2016						18			14	[5]						7	[6]				94
2017-2021						$ 82			$ 123	[5]						$ 36	[6]				$ 515

[1] Employer contributions for 2012 are expected to approximate $97 million for the FCX plans, $14 million for the PT Freeport Indonesia plan (based on a December 31, 2011, exchange rate of 9,060 Indonesian rupiah to one U.S. dollar) and $9 million for the Atlantic Copper plan (based on a December 31, 2011, exchange rate of $1.29 per euro).

[2] The discount rate shown in 2011 and 2010 for the FCX plans relates to all plans except the SERP plan. The SERP plan’s discount rate in 2011 and 2010 was 4.00 percent.

[3] The rate of compensation increase shown for the FCX plans only relates to the FMC plans. The rate of compensation increase shown for the PT Freeport Indonesia plan relates to the years after 2012. For the PT Freeport Indonesia plan, the rate of compensation increase for 2012 ranges from 10 percent to 13 percent.

[4] The assumptions shown only relate to the FMC plans.

[5] Based on a December 31, 2011, exchange rate of 9,060 Indonesian rupiah to one U.S. dollar.

[6] Based on a December 31, 2011, exchange rate of $1.29 per euro.