GUARANTOR FINANCIAL STATEMENTS (Condensed Consolidating Comprehensive (Loss) Income) (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
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues	$ 5,041	$ 4,310	$ 3,711	$ 3,341	$ 4,377	$ 3,877	$ 3,334	$ 3,242	$ 16,403	$ 14,830	$ 14,607
Costs and Expenses									12,770	17,622	28,119
Operating income (loss)	1,467	917	669	580	703	359	18	(3,872)	3,633	(2,792)	(13,512)
Interest expense, net									(801)	(755)	(617)
Nonoperating Income (Expense)									49	49
Other income, net									49	49	1
Net gain on early extinguishment and exchanges of debt									21	26	0
(Loss) income before income taxes and equity in affiliated companies' net (losses) earnings									2,902	(3,472)	(14,128)
Benefit from (provision for) income taxes									(883)	(371)	1,951
Equity in affiliated companies’ net earnings (losses)									10	11	(3)
Net income (loss) from continuing operations	1,193	242	326	268	202	292	(229)	(4,097)	2,029	(3,832)	(12,180)
Net income (loss) from discontinued operations	16	3	9	38	(2)	(6)	(181)	(4)	66	(193)	91
Net income (loss)	1,209	245	335	306	200	286	(410)	(4,101)	2,095	(4,025)	(12,089)
Income (Loss) From Continuing Operations Attributable to Noncontrolling Entity and Preferred Dividends									274	66	68
Net income (loss) attributable to noncontrolling interests: Discontinued Operations	0	0	1	3	19	22	12	10	4	63	79
Net (loss) income attributable to common stockholders	$ 1,041	$ 280	$ 268	$ 228	$ 292	$ 217	$ (479)	$ (4,184)	1,817	(4,154)	(12,236)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									61	(45)	41
Total comprehensive income (loss)									1,878	(4,199)	(12,195)
Eliminations
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									0	0	0
Costs and Expenses									10	10	(11)
Operating income (loss)									(10)	(10)	11
Interest expense, net									348	333	152
Nonoperating Income (Expense)									(348)	(292)
Other income, net											(139)
Net gain on early extinguishment and exchanges of debt									0	0
(Loss) income before income taxes and equity in affiliated companies' net (losses) earnings									(10)	31	24
Benefit from (provision for) income taxes									3	(12)	(9)
Equity in affiliated companies’ net earnings (losses)									(1,408)	9,511	31,496
Net income (loss) from continuing operations									(1,415)	9,530	31,511
Net income (loss) from discontinued operations									0	(39)	0
Net income (loss)									(1,415)	9,491	31,511
Income (Loss) From Continuing Operations Attributable to Noncontrolling Entity and Preferred Dividends									124	66	33
Net income (loss) attributable to noncontrolling interests: Discontinued Operations									0	0	0
Net (loss) income attributable to common stockholders									(1,539)	9,425	31,478
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									(61)	45	(41)
Total comprehensive income (loss)									(1,600)	9,470	31,437
FCX Issuer
Condensed Comprehensive (Loss) Income Statements [Line Items]
Net gain on early extinguishment and exchanges of debt										26
FCX Issuer | Reportable Legal Entities
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									0	0	0
Costs and Expenses									42	75	60
Operating income (loss)									(42)	(75)	(60)
Interest expense, net									(467)	(534)	(489)
Nonoperating Income (Expense)									339	271
Other income, net											225
Net gain on early extinguishment and exchanges of debt									22
(Loss) income before income taxes and equity in affiliated companies' net (losses) earnings									(148)	(312)	(324)
Benefit from (provision for) income taxes									220	(2,233)	(3,227)
Equity in affiliated companies’ net earnings (losses)									1,745	(1,609)	(8,685)
Net income (loss) from continuing operations									1,817	(4,154)	(12,236)
Net income (loss) from discontinued operations									0	0	0
Net income (loss)									1,817	(4,154)	(12,236)
Income (Loss) From Continuing Operations Attributable to Noncontrolling Entity and Preferred Dividends									0	0	0
Net income (loss) attributable to noncontrolling interests: Discontinued Operations									0	0	0
Net (loss) income attributable to common stockholders									1,817	(4,154)	(12,236)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									61	(45)	41
Total comprehensive income (loss)									1,878	(4,199)	(12,195)
FM O&G LLC Guarantor
Condensed Comprehensive (Loss) Income Statements [Line Items]
Impairment of oil and gas properties										1,500	4,200
FM O&G LLC Guarantor | Reportable Legal Entities
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									52	379	613
Costs and Expenses									78	3,074	5,150
Operating income (loss)									(26)	(2,695)	(4,537)
Interest expense, net									(227)	(56)	(8)
Nonoperating Income (Expense)									0	0
Other income, net											1
Net gain on early extinguishment and exchanges of debt									5	0
(Loss) income before income taxes and equity in affiliated companies' net (losses) earnings									(248)	(2,751)	(4,544)
Benefit from (provision for) income taxes									(108)	1,053	1,718
Equity in affiliated companies’ net earnings (losses)									10	(3,101)	(9,976)
Net income (loss) from continuing operations									(346)	(4,799)	(12,802)
Net income (loss) from discontinued operations									0	0	0
Net income (loss)									(346)	(4,799)	(12,802)
Income (Loss) From Continuing Operations Attributable to Noncontrolling Entity and Preferred Dividends									0	0	0
Net income (loss) attributable to noncontrolling interests: Discontinued Operations									0	0	0
Net (loss) income attributable to common stockholders									(346)	(4,799)	(12,802)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									0	0	0
Total comprehensive income (loss)									(346)	(4,799)	(12,802)
Non-Guarantor Subsidiaries
Condensed Comprehensive (Loss) Income Statements [Line Items]
Impairment of oil and gas properties										2,800	8,900
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Comprehensive (Loss) Income Statements [Line Items]
Revenues									16,351	14,451	13,994
Costs and Expenses									12,640	14,463	22,920
Operating income (loss)									3,711	(12)	(8,926)
Interest expense, net									(455)	(498)	(272)
Nonoperating Income (Expense)									58	70
Other income, net											(86)
Net gain on early extinguishment and exchanges of debt									(6)	0
(Loss) income before income taxes and equity in affiliated companies' net (losses) earnings									3,308	(440)	(9,284)
Benefit from (provision for) income taxes									(998)	821	3,469
Equity in affiliated companies’ net earnings (losses)									(337)	(4,790)	(12,838)
Net income (loss) from continuing operations									1,973	(4,409)	(18,653)
Net income (loss) from discontinued operations									66	(154)	91
Net income (loss)									2,039	(4,563)	(18,562)
Income (Loss) From Continuing Operations Attributable to Noncontrolling Entity and Preferred Dividends									150	0	35
Net income (loss) attributable to noncontrolling interests: Discontinued Operations									4	63	79
Net (loss) income attributable to common stockholders									1,885	(4,626)	(18,676)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent									61	(45)	41
Total comprehensive income (loss)									$ 1,946	$ (4,671)	$ (18,635)