GUARANTOR FINANCIAL STATEMENTS (Condensed Consolidating Comprehensive (Loss) Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues	$ 3,911	$ 3,153	$ 3,546	$ 3,792	$ 3,684	$ 4,908	$ 5,168	$ 4,868	$ 14,402	$ 18,628	$ 16,403
Costs and Expenses									13,311	13,874	12,713
Operating income (loss)	775	(38)	33	321	316	1,315	1,664	1,459	1,091	4,754	3,690
Interest expense, net									(620)	(945)	(801)
Other (expense) income, net									(138)	76	(8)
Net (loss) gain on early extinguishment of debt									(27)	7	21
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									(138)	76
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									306	3,892	2,902
Benefit from (provision for) income taxes									(510)	(991)	(883)
Equity in affiliated companies’ net earnings (losses)									12	8	10
Net (loss) income from continuing operations	42	(235)	(74)	75	374	668	1,039	828	(192)	2,909	2,029
Net income (loss) from discontinued operations	1	1	0	1	4	(4)	(4)	(11)	3	(15)	66
Net (loss) income	43	(234)	(74)	76	378	664	1,035	817	(189)	2,894	2,095
Net income from continuing operations attributable to noncontrolling interests											(274)
Net income (loss) attributable to noncontrolling interests: Discontinued Operations									0	0	4
Net (loss) income attributable to common stockholders	$ 9	$ (207)	$ (72)	$ 31	$ 485	$ 556	$ 869	$ 692	(239)	2,602	1,817
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(71)	(33)	61
Total comprehensive income (loss) attributable to common stockholders									(310)	2,569	1,878
Eliminations
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									0	0	0
Costs and Expenses									(12)	(10)	10
Operating income (loss)									12	10	(10)
Interest expense, net									533	478	348
Other (expense) income, net											(348)
Net (loss) gain on early extinguishment of debt									0	0	0
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									(21)	(478)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									524	10	(10)
Benefit from (provision for) income taxes									(2)	(2)	3
Equity in affiliated companies’ net earnings (losses)									293	(2,493)	(1,408)
Net (loss) income from continuing operations									815	(2,485)	(1,415)
Net income (loss) from discontinued operations									0	0	0
Net (loss) income									815	(2,485)	(1,415)
Net income from continuing operations attributable to noncontrolling interests											(124)
Net income (loss) attributable to noncontrolling interests: Discontinued Operations											0
Net (loss) income attributable to common stockholders									851	(2,709)	(1,539)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									71	33	(61)
Total comprehensive income (loss) attributable to common stockholders									922	(2,676)	(1,600)
FCX Issuer
Condensed Comprehensive (Loss) Income Statements [Line Items]
Net (loss) gain on early extinguishment of debt										7
FCX Issuer | Reportable Legal Entities
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									0	0	0
Costs and Expenses									25	28	39
Operating income (loss)									(25)	(28)	(39)
Interest expense, net									(337)	(388)	(467)
Other (expense) income, net											336
Net (loss) gain on early extinguishment of debt									(26)		22
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									(22)	477
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									(410)	68	(148)
Benefit from (provision for) income taxes									58	(176)	220
Equity in affiliated companies’ net earnings (losses)									113	2,710	1,745
Net (loss) income from continuing operations									(239)	2,602	1,817
Net income (loss) from discontinued operations									0	0	0
Net (loss) income									(239)	2,602	1,817
Net income from continuing operations attributable to noncontrolling interests											0
Net income (loss) attributable to noncontrolling interests: Discontinued Operations											0
Net (loss) income attributable to common stockholders									(239)	2,602	1,817
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(71)	(33)	61
Total comprehensive income (loss) attributable to common stockholders									(310)	2,569	1,878
FM O&G LLC Guarantor | Reportable Legal Entities
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									40	59	52
Costs and Expenses									54	58	78
Operating income (loss)									(14)	1	(26)
Interest expense, net									(322)	(301)	(227)
Other (expense) income, net											0
Net (loss) gain on early extinguishment of debt									0	2	5
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									(336)	(298)	(248)
Benefit from (provision for) income taxes									76	61	(108)
Equity in affiliated companies’ net earnings (losses)									(73)	10	10
Net (loss) income from continuing operations									(333)	(227)	(346)
Net income (loss) from discontinued operations									0	0	0
Net (loss) income									(333)	(227)	(346)
Net income from continuing operations attributable to noncontrolling interests											0
Net income (loss) attributable to noncontrolling interests: Discontinued Operations											0
Net (loss) income attributable to common stockholders									(333)	(227)	(346)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									0	0	0
Total comprehensive income (loss) attributable to common stockholders									(333)	(227)	(346)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									14,362	18,569	16,351
Costs and Expenses									13,244	13,798	12,586
Operating income (loss)									1,118	4,771	3,765
Interest expense, net									(494)	(734)	(455)
Other (expense) income, net											4
Net (loss) gain on early extinguishment of debt									(1)	(2)	(6)
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									(95)	77
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									528	4,112	3,308
Benefit from (provision for) income taxes									(642)	(874)	(998)
Equity in affiliated companies’ net earnings (losses)									(321)	(219)	(337)
Net (loss) income from continuing operations									(435)	3,019	1,973
Net income (loss) from discontinued operations									3	(15)	66
Net (loss) income									(432)	3,004	2,039
Net income from continuing operations attributable to noncontrolling interests											(150)
Net income (loss) attributable to noncontrolling interests: Discontinued Operations											4
Net (loss) income attributable to common stockholders									(518)	2,936	1,885
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(71)	(33)	61
Total comprehensive income (loss) attributable to common stockholders									$ (589)	$ 2,903	$ 1,946