Guarantor Financial Statements (Unaudited) Condensed Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues	$ 4,908	$ 4,310	$ 14,944	$ 11,362
Total costs and expenses	3,593	3,382	10,506	9,151
Operating income (loss)	1,315	928	4,438	2,211
Interest expense, net	(143)	(304)	(436)	(633)
Other Nonoperating Income (Expense)	14	2	71	(1)
Net gain on early extinguishment of debt	0	11	8	8
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings	1,186	626	4,073	1,577
Provision for income taxes	(522)	(387)	(1,543)	(747)
Equity in affiliated companies’ net earnings (losses)	4	3	5	6
Net income from continuing operations	668	242	2,535	836
Net (loss) income from discontinued operations	(4)	3	(19)	50
Net income	664	245	2,516	886
Net (income) loss from continuing operations attributable to noncontrolling interests	(108)	35	(399)	(106)
Net income from discontinued operations attributable to noncontrolling interests	0	0	0	(4)
Net income attributable to common stockholders	556	280	2,117	776
Other comprehensive income (loss)	11	13	34	105
Total comprehensive income (loss)	567	293	2,151	881
Eliminations [Member]
Revenues	0	0	0	0
Total costs and expenses	0	(1)	(10)	11
Operating income (loss)	0	1	10	(11)
Interest expense, net	125	89	350	252
Other Nonoperating Income (Expense)	(125)	(89)	(350)	(252)
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings	0	1	10	(11)
Provision for income taxes	0	0	(2)	4
Equity in affiliated companies’ net earnings (losses)	(656)	(283)	(2,208)	(907)
Net income from continuing operations	(656)	(282)	(2,200)	(914)
Net (loss) income from discontinued operations	0	0	0	0
Net income	(656)	(282)	(2,200)	(914)
Net (income) loss from continuing operations attributable to noncontrolling interests	(61)	(34)	(179)	(64)
Net income from discontinued operations attributable to noncontrolling interests				0
Net income attributable to common stockholders	(717)	(316)	(2,379)	(978)
Other comprehensive income (loss)	(11)	(13)	(34)	(105)
Total comprehensive income (loss)	(728)	(329)	(2,413)	(1,083)
FCX Issuer [Member] | Reportable Legal Entities [Member]
Revenues	0	0	0	0
Total costs and expenses	7	8	20	30
Operating income (loss)	(7)	(8)	(20)	(30)
Interest expense, net	(93)	(116)	(294)	(355)
Other Nonoperating Income (Expense)	124	97	357	255
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings	24	(27)	43	(130)
Provision for income taxes	(188)	21	(282)	(111)
Equity in affiliated companies’ net earnings (losses)	720	286	2,356	1,017
Net income from continuing operations	556	280	2,117	776
Net (loss) income from discontinued operations	0	0	0	0
Net income	556	280	2,117	776
Net (income) loss from continuing operations attributable to noncontrolling interests	0	0	0	0
Net income from discontinued operations attributable to noncontrolling interests				0
Net income attributable to common stockholders	556	280	2,117	776
Other comprehensive income (loss)	11	13	34	105
Total comprehensive income (loss)	567	293	2,151	881
FM O&G LLC Guarantor [Member] | Reportable Legal Entities [Member]
Revenues	15	13	46	38
Total costs and expenses	(2)	25	(10)	86
Operating income (loss)	17	(12)	56	(48)
Interest expense, net	(79)	(59)	(219)	(167)
Other Nonoperating Income (Expense)	0	3	2	3
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings	(62)	(68)	(161)	(212)
Provision for income taxes	11	24	33	74
Equity in affiliated companies’ net earnings (losses)	(6)	20	(10)	14
Net income from continuing operations	(57)	(24)	(138)	(124)
Net (loss) income from discontinued operations	0	0	0	0
Net income	(57)	(24)	(138)	(124)
Net (income) loss from continuing operations attributable to noncontrolling interests	0	0	0	0
Net income from discontinued operations attributable to noncontrolling interests				0
Net income attributable to common stockholders	(57)	(24)	(138)	(124)
Other comprehensive income (loss)	0	0	0	0
Total comprehensive income (loss)	(57)	(24)	(138)	(124)
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Revenues	4,893	4,297	14,898	11,324
Total costs and expenses	3,588	3,350	10,506	9,024
Operating income (loss)	1,305	947	4,392	2,300
Interest expense, net	(96)	(218)	(273)	(363)
Other Nonoperating Income (Expense)	15	(9)	62	(7)
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings	1,224	720	4,181	1,930
Provision for income taxes	(345)	(432)	(1,292)	(714)
Equity in affiliated companies’ net earnings (losses)	(54)	(20)	(133)	(118)
Net income from continuing operations	825	268	2,756	1,098
Net (loss) income from discontinued operations	(4)	3	(19)	50
Net income	821	271	2,737	1,148
Net (income) loss from continuing operations attributable to noncontrolling interests	(47)	69	(220)	(42)
Net income from discontinued operations attributable to noncontrolling interests				(4)
Net income attributable to common stockholders	774	340	2,517	1,102
Other comprehensive income (loss)	11	13	34	105
Total comprehensive income (loss)	$ 785	$ 353	$ 2,551	$ 1,207