GUARANTOR FINANCIAL STATEMENTS (Condensed Consolidated Cash Flow Statement) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Cash Flow Statements [Line Items]
Revenues	$ 3,684	$ 4,908	$ 5,168	$ 4,868	$ 5,041	$ 4,310	$ 3,711	$ 3,341	$ 18,628	$ 16,403	$ 14,830
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	4,455				4,710				4,455	4,710	4,420	$ 341
Cash flow from operating activities:
Net income (loss)	378	664	1,035	817	1,209	245	335	306	2,894	2,095	(4,025)
Costs and Expenses									13,874	12,713	17,559
Operating income (loss)	316	1,315	1,664	1,459	1,479	928	686	597	4,754	3,690	(2,729)
Interest expense, net									(945)	(801)	(755)
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									76	(8)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									3,892	2,902	(3,472)
Provision for (benefit from) income taxes									991	883	371
Net income (loss) from continuing operations	374	668	1,039	828	1,193	242	326	268	2,909	2,029	(3,832)
Net (loss) income from discontinued operations	4	(4)	(4)	(11)	16	3	9	38	(15)	66	(193)
Net income from continuing operations attributable to noncontrolling interests									(292)	(274)	(227)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest					0	0	1	3	0	4	63
Net (loss) income attributable to common stockholders	485	$ 556	$ 869	$ 692	1,041	$ 280	$ 268	$ 228	2,602	1,817	(4,154)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(33)	61	(45)
Total comprehensive income (loss) attributable to common stockholders									2,569	1,878	(4,199)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization									1,754	1,714	2,610
Impairment of Oil and Gas Properties									0	0	4,317
Net gain on sales of assets									(208)	(81)	(649)
Equity in affiliated companies’ net earnings									8	10	11
Net cash (used in) provided by operating activities									3,863	4,666	3,737
Cash flow from investing activities:
Capital expenditures									(1,971)	(1,410)	(2,813)
Acquisition of PT Rio Tinto Indonesia									(3,500)	0	0
Intercompany loans									0	0	0
Dividends from (investments in) consolidated subsidiaries									0	0	0
Other, net									453
Other, net										(89)	6,366
Net cash provided by (used in) investing activities									(5,018)	(1,321)	3,553
Cash flow from financing activities:
Proceeds from debt									632	955	3,681
Repayments of debt									(2,717)	(3,812)	(7,625)
Intercompany loans									0	0	0
Proceeds from sale of common stock									0	0	1,515
Proceeds from sale of PT Freeport Indonesia shares of Equity									3,500	0	0
Cash dividends paid and distributions received, net									(496)	(176)	(699)
Other, net									(19)	(22)	(38)
Net cash provided by (used in) financing activities									900	(3,055)	(3,166)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect									(255)	290
Net (decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents											4,124
Increase in cash and cash equivalents in assets held for sale									0	0	(45)
Cash, cash equivalents, restricted cash and restricted cash equivalents at end of year	4,217				4,526				4,217	4,526
Reportable Legal Entities | FCX Issuer
Condensed Cash Flow Statements [Line Items]
Revenues									0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0				0				0	0	0	0
Cash flow from operating activities:
Net income (loss)									2,602	1,817	(4,154)
Costs and Expenses									28	39	72
Operating income (loss)									(28)	(39)	(72)
Interest expense, net									(388)	(467)	(534)
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									477	336
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									68	(148)	(312)
Provision for (benefit from) income taxes									176	(220)	2,233
Net income (loss) from continuing operations									2,602	1,817	(4,154)
Net (loss) income from discontinued operations									0	0	0
Net income from continuing operations attributable to noncontrolling interests									0	0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest										0	0
Net (loss) income attributable to common stockholders									2,602	1,817	(4,154)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(33)	61	(45)
Total comprehensive income (loss) attributable to common stockholders									2,569	1,878	(4,199)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings									2,710	1,745	(1,609)
Net cash (used in) provided by operating activities									(40)	(156)	(137)
Cash flow from investing activities:
Capital expenditures									(2)	0	0
Acquisition of PT Rio Tinto Indonesia									0
Intercompany loans									(832)	(777)	481
Dividends from (investments in) consolidated subsidiaries									2,475	3,226	1,469
Other, net									460
Other, net										0	2
Net cash provided by (used in) investing activities									2,101	2,449	1,952
Cash flow from financing activities:
Proceeds from debt									0	0	1,721
Repayments of debt									(1,826)	(2,281)	(5,011)
Intercompany loans									0	0	0
Proceeds from sale of common stock											1,515
Proceeds from sale of PT Freeport Indonesia shares of Equity									0
Cash dividends paid and distributions received, net									(217)	(2)	(6)
Other, net									(18)	(10)	(34)
Net cash provided by (used in) financing activities									(2,061)	(2,293)	(1,815)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect									0	0
Net (decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents											0
Increase in cash and cash equivalents in assets held for sale											0
Reportable Legal Entities | FM O&G LLC Guarantor
Condensed Cash Flow Statements [Line Items]
Revenues									59	52	379
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	0				8				0	8	10	0
Cash flow from operating activities:
Net income (loss)									(227)	(346)	(4,799)
Costs and Expenses									58	78	3,074
Operating income (loss)									1	(26)	(2,695)
Interest expense, net									(301)	(227)	(56)
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									(298)	(248)	(2,751)
Provision for (benefit from) income taxes									(61)	108	(1,053)
Net income (loss) from continuing operations									(227)	(346)	(4,799)
Net (loss) income from discontinued operations									0	0	0
Net income from continuing operations attributable to noncontrolling interests									0	0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest										0	0
Net (loss) income attributable to common stockholders									(227)	(346)	(4,799)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									0	0	0
Total comprehensive income (loss) attributable to common stockholders									(227)	(346)	(4,799)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings									10	10	(3,101)
Net cash (used in) provided by operating activities									(487)	(467)	(263)
Cash flow from investing activities:
Capital expenditures									0	(25)	(567)
Acquisition of PT Rio Tinto Indonesia									0
Intercompany loans									0	0	(346)
Dividends from (investments in) consolidated subsidiaries									0	(15)	(45)
Other, net									6
Other, net										(57)	1,673
Net cash provided by (used in) investing activities									6	17	715
Cash flow from financing activities:
Proceeds from debt									0	0	0
Repayments of debt									(53)	(205)	0
Intercompany loans									526	663	(332)
Proceeds from sale of common stock											0
Proceeds from sale of PT Freeport Indonesia shares of Equity									0
Cash dividends paid and distributions received, net									0	0	(107)
Other, net									0	(10)	(3)
Net cash provided by (used in) financing activities									473	448	(442)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect									(8)	(2)
Net (decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents											10
Increase in cash and cash equivalents in assets held for sale											0
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Cash Flow Statements [Line Items]
Revenues									18,569	16,351	14,451
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	4,455				4,702				4,455	4,702	4,410	341
Cash flow from operating activities:
Net income (loss)									3,004	2,039	(4,563)
Costs and Expenses									13,798	12,586	14,403
Operating income (loss)									4,771	3,765	48
Interest expense, net									(734)	(455)	(498)
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									77	4
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									4,112	3,308	(440)
Provision for (benefit from) income taxes									874	998	(821)
Net income (loss) from continuing operations									3,019	1,973	(4,409)
Net (loss) income from discontinued operations									(15)	66	(154)
Net income from continuing operations attributable to noncontrolling interests									(68)	(150)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest										4	63
Net (loss) income attributable to common stockholders									2,936	1,885	(4,626)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(33)	61	(45)
Total comprehensive income (loss) attributable to common stockholders									2,903	1,946	(4,671)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings									(219)	(337)	(4,790)
Net cash (used in) provided by operating activities									4,390	5,289	4,135
Cash flow from investing activities:
Capital expenditures									(1,969)	(1,385)	(2,248)
Acquisition of PT Rio Tinto Indonesia									(3,500)
Intercompany loans									0	0	0
Dividends from (investments in) consolidated subsidiaries									84	120	176
Other, net									(13)
Other, net										(32)	4,695
Net cash provided by (used in) investing activities									(5,398)	(1,233)	2,623
Cash flow from financing activities:
Proceeds from debt									632	955	1,960
Repayments of debt									(838)	(1,326)	(2,614)
Intercompany loans									306	114	197
Proceeds from sale of common stock											3,388
Proceeds from sale of PT Freeport Indonesia shares of Equity									3,710
Cash dividends paid and distributions received, net									(3,032)	(3,440)	(5,555)
Other, net									(17)	(67)	(20)
Net cash provided by (used in) financing activities									761	(3,764)	(2,644)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect									(247)	292
Net (decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents											4,114
Increase in cash and cash equivalents in assets held for sale											(45)
Eliminations
Condensed Cash Flow Statements [Line Items]
Revenues									0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 0				$ 0				0	0	0	$ 0
Cash flow from operating activities:
Net income (loss)									(2,485)	(1,415)	9,491
Costs and Expenses									(10)	10	10
Operating income (loss)									10	(10)	(10)
Interest expense, net									478	348	333
Other Operating Income (Expense) Including Gain (Loss) on Early Extinguishment of Debt									(478)	(348)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest									10	(10)	31
Provision for (benefit from) income taxes									2	(3)	12
Net income (loss) from continuing operations									(2,485)	(1,415)	9,530
Net (loss) income from discontinued operations									0	0	(39)
Net income from continuing operations attributable to noncontrolling interests									(224)	(124)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest										0	0
Net (loss) income attributable to common stockholders									(2,709)	(1,539)	9,425
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									33	(61)	45
Total comprehensive income (loss) attributable to common stockholders									(2,676)	(1,600)	9,470
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings									(2,493)	(1,408)	9,511
Net cash (used in) provided by operating activities									0	0	2
Cash flow from investing activities:
Capital expenditures									0	0	2
Acquisition of PT Rio Tinto Indonesia									0
Intercompany loans									832	777	(135)
Dividends from (investments in) consolidated subsidiaries									(2,559)	(3,331)	(1,600)
Other, net									0
Other, net										0	(4)
Net cash provided by (used in) investing activities									(1,727)	(2,554)	(1,737)
Cash flow from financing activities:
Proceeds from debt									0	0	0
Repayments of debt									0	0	0
Intercompany loans									(832)	(777)	135
Proceeds from sale of common stock											(3,388)
Proceeds from sale of PT Freeport Indonesia shares of Equity									(210)
Cash dividends paid and distributions received, net									2,753	3,266	4,969
Other, net									16	65	19
Net cash provided by (used in) financing activities									1,727	2,554	1,735
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect									0	0
Net (decrease) increase in cash, cash equivalents, restricted cash and restricted cash equivalents											0
Increase in cash and cash equivalents in assets held for sale											$ 0
Freeport-McMoRan Oil & Gas
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net gain on sales of assets									$ (27)
Cash flow from investing activities:
Proceeds from sales										$ 80