GUARANTOR FINANCIAL STATEMENTS (Condensed Consolidated Cash Flow Statement) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flow from operating activities:
Net income (loss)	$ 1,209	$ 245	$ 335	$ 306	$ 200	$ 286	$ (410)	$ (4,101)	$ 2,095	$ (4,025)	$ (12,089)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization									1,714	2,610	3,497
Impairment of Oil and Gas Properties						$ 200	$ 300	3,800	0	4,317	13,144
Net gain on sales of assets									(81)	(649)	(39)
Metals inventory adjustments									8	36	338
Equity in affiliated companies’ net earnings (losses)									10	11	(3)
Mining asset impairments and restructuring									40	20	119
Net cash (used in) provided by operating activities									4,682	3,729	3,220
Cash flow from investing activities:
Capital expenditures									(1,410)	(2,813)	(6,353)
Intercompany loans									0	0	0
Dividends from (investments in) consolidated subsidiaries									0	0	(2)
Proceeds From Divestiture Of Business And Interests In Affiliates And Proceeds From Sale Of Other Assets									47
Other, net										(6,363)	109
Net cash provided by (used in) investing activities									(1,363)	3,550	(6,246)
Cash flow from financing activities:
Proceeds from debt									955	3,681	8,272
Repayments of debt									(3,812)	(7,625)	(6,677)
Intercompany loans									0	0	0
Net proceeds from sale of common stock									0	1,515	1,936
Cash dividends paid and distributions received, net									(176)	(699)	(725)
Other, net									(22)	(38)	(20)
Net cash (used in) provided by financing activities									(3,055)	(3,166)	2,786
Net increase in cash and cash equivalents									264	4,113	(240)
(Increase) decrease in cash and cash equivalents in assets held for sale									(62)	(45)	119
Cash and cash equivalents at beginning of year				4,245				177	4,245	177	298
Cash and cash equivalents at end of year	4,447				4,245				4,447	4,245	177
Reportable Legal Entities | FCX Issuer
Cash flow from operating activities:
Net income (loss)									1,817	(4,154)	(12,236)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings (losses)									1,745	(1,609)	(8,685)
Net cash (used in) provided by operating activities									(156)	(137)	(167)
Cash flow from investing activities:
Capital expenditures									0	0	(7)
Intercompany loans									(777)	481	(1,812)
Dividends from (investments in) consolidated subsidiaries									3,226	1,469	852
Proceeds From Divestiture Of Business And Interests In Affiliates And Proceeds From Sale Of Other Assets									0
Other, net										(2)	(21)
Net cash provided by (used in) investing activities									2,449	1,952	(988)
Cash flow from financing activities:
Proceeds from debt									0	1,721	4,503
Repayments of debt									(2,281)	(5,011)	(4,660)
Intercompany loans									0	0	0
Net proceeds from sale of common stock										1,515	1,936
Cash dividends paid and distributions received, net									(2)	(6)	(605)
Other, net									(10)	(34)	(19)
Net cash (used in) provided by financing activities									(2,293)	(1,815)	1,155
Net increase in cash and cash equivalents									0	0	0
(Increase) decrease in cash and cash equivalents in assets held for sale									0	0	0
Cash and cash equivalents at beginning of year				0				0	0	0	0
Cash and cash equivalents at end of year	0				0				0	0	0
Reportable Legal Entities | FM O&G LLC Guarantor
Cash flow from operating activities:
Net income (loss)									(346)	(4,799)	(12,802)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings (losses)									10	(3,101)	(9,976)
Net cash (used in) provided by operating activities									(467)	(271)	262
Cash flow from investing activities:
Capital expenditures									(25)	(567)	(847)
Intercompany loans									0	(346)	(1,310)
Dividends from (investments in) consolidated subsidiaries									(15)	(45)	(71)
Proceeds From Divestiture Of Business And Interests In Affiliates And Proceeds From Sale Of Other Assets									57
Other, net										(1,673)	(2)
Net cash provided by (used in) investing activities									17	715	(2,230)
Cash flow from financing activities:
Proceeds from debt									0	0	0
Repayments of debt									(205)	0	0
Intercompany loans									663	(332)	2,038
Net proceeds from sale of common stock										0	0
Cash dividends paid and distributions received, net									0	(107)	0
Other, net									(10)	(3)	(71)
Net cash (used in) provided by financing activities									448	(442)	1,967
Net increase in cash and cash equivalents									(2)	2	(1)
(Increase) decrease in cash and cash equivalents in assets held for sale									0	0	0
Cash and cash equivalents at beginning of year				2				0	2	0	1
Cash and cash equivalents at end of year	0				2				0	2	0
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash flow from operating activities:
Net income (loss)									2,039	(4,563)	(18,562)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings (losses)									(337)	(4,790)	(12,838)
Net cash (used in) provided by operating activities									5,305	4,135	3,112
Cash flow from investing activities:
Capital expenditures									(1,385)	(2,248)	(5,486)
Intercompany loans									0	0	0
Dividends from (investments in) consolidated subsidiaries									120	176	130
Proceeds From Divestiture Of Business And Interests In Affiliates And Proceeds From Sale Of Other Assets									(10)
Other, net										(4,692)	111
Net cash provided by (used in) investing activities									(1,275)	2,620	(5,245)
Cash flow from financing activities:
Proceeds from debt									955	1,960	3,769
Repayments of debt									(1,326)	(2,614)	(2,017)
Intercompany loans									114	197	1,084
Net proceeds from sale of common stock										3,388	0
Cash dividends paid and distributions received, net									(3,440)	(5,555)	(924)
Other, net									(67)	(20)	(18)
Net cash (used in) provided by financing activities									(3,764)	(2,644)	1,894
Net increase in cash and cash equivalents									266	4,111	(239)
(Increase) decrease in cash and cash equivalents in assets held for sale									(62)	(45)	119
Cash and cash equivalents at beginning of year				4,243				177	4,243	177	297
Cash and cash equivalents at end of year	4,447				4,243				4,447	4,243	177
Eliminations
Cash flow from operating activities:
Net income (loss)									(1,415)	9,491	31,511
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in affiliated companies’ net earnings (losses)									(1,408)	9,511	31,496
Net cash (used in) provided by operating activities									0	2	13
Cash flow from investing activities:
Capital expenditures									0	2	(13)
Intercompany loans									777	(135)	3,122
Dividends from (investments in) consolidated subsidiaries									(3,331)	(1,600)	(913)
Proceeds From Divestiture Of Business And Interests In Affiliates And Proceeds From Sale Of Other Assets									0
Other, net										4	21
Net cash provided by (used in) investing activities									(2,554)	(1,737)	2,217
Cash flow from financing activities:
Proceeds from debt									0	0	0
Repayments of debt									0	0	0
Intercompany loans									(777)	135	(3,122)
Net proceeds from sale of common stock										(3,388)	0
Cash dividends paid and distributions received, net									3,266	4,969	804
Other, net									65	19	88
Net cash (used in) provided by financing activities									2,554	1,735	(2,230)
Net increase in cash and cash equivalents									0	0	0
(Increase) decrease in cash and cash equivalents in assets held for sale									0	0	0
Cash and cash equivalents at beginning of year				$ 0				$ 0	0	0	0
Cash and cash equivalents at end of year	$ 0				$ 0				$ 0	$ 0	$ 0