Guarantor Financial Statements (Unaudited) Condensed Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues	$ 5,168	$ 3,711	$ 10,036	$ 7,052
Total costs and expenses	3,504	3,025	6,913	5,769
Operating income (loss)	1,664	686	3,123	1,283
Interest expense, net	(142)	(162)	(293)	(329)
Other Nonoperating Income (Expense)	29	(11)	57	(3)
Net gain (loss) on early extinguishment of debt	9	(4)	8	(3)
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings (losses)	1,551	513	2,887	951
Provision for income taxes	(515)	(186)	(1,021)	(360)
Equity in affiliated companies’ net earnings (losses)	3	(1)	1	3
Net income from continuing operations	1,039	326	1,867	594
Net (loss) income from discontinued operations	(4)	9	(15)	47
Net income (loss)	1,035	335	1,852	641
Net income from continuing operations attributable to noncontrolling interests	(166)	(66)	(291)	(141)
Net income from discontinued operations attributable to noncontrolling interests	0	(1)	0	(4)
Net income attributable to common stockholders	869	268	1,561	496
Other comprehensive income (loss)	11	81	23	92
Total comprehensive income (loss)	880	349	1,584	588
Eliminations [Member]
Revenues	0	0	0	0
Total costs and expenses	(9)	10	(10)	12
Operating income (loss)	9	(10)	10	(12)
Interest expense, net	123	84	225	163
Other Nonoperating Income (Expense)	(123)	(84)	(225)	(163)
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings (losses)	9	(10)	10	(12)
Provision for income taxes	(2)	3	(2)	4
Equity in affiliated companies’ net earnings (losses)	(803)	(304)	(1,552)	(624)
Net income from continuing operations	(796)	(311)	(1,544)	(632)
Net (loss) income from discontinued operations	0	0	0	0
Net income (loss)	(796)	(311)	(1,544)	(632)
Net income from continuing operations attributable to noncontrolling interests	(64)	(20)	(118)	(30)
Net income from discontinued operations attributable to noncontrolling interests		0		0
Net income attributable to common stockholders	(860)	(331)	(1,662)	(662)
Other comprehensive income (loss)	(11)	(81)	(23)	(92)
Total comprehensive income (loss)	(871)	(412)	(1,685)	(754)
FCX Issuer [Member] | Reportable Legal Entities [Member]
Revenues	0	0	0	0
Total costs and expenses	4	14	13	22
Operating income (loss)	(4)	(14)	(13)	(22)
Interest expense, net	(97)	(117)	(201)	(239)
Other Nonoperating Income (Expense)	132	80	233	158
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings (losses)	31	(51)	19	(103)
Provision for income taxes	(11)	(72)	(94)	(132)
Equity in affiliated companies’ net earnings (losses)	849	391	1,636	731
Net income from continuing operations	869	268	1,561	496
Net (loss) income from discontinued operations	0	0	0	0
Net income (loss)	869	268	1,561	496
Net income from continuing operations attributable to noncontrolling interests	0	0	0	0
Net income from discontinued operations attributable to noncontrolling interests		0		0
Net income attributable to common stockholders	869	268	1,561	496
Other comprehensive income (loss)	11	81	23	92
Total comprehensive income (loss)	880	349	1,584	588
FM O&G LLC Guarantor [Member] | Reportable Legal Entities [Member]
Revenues	16	12	31	25
Total costs and expenses	(16)	11	(8)	61
Operating income (loss)	32	1	39	(36)
Interest expense, net	(76)	(55)	(140)	(108)
Other Nonoperating Income (Expense)	2	0	2	0
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings (losses)	(42)	(54)	(99)	(144)
Provision for income taxes	10	19	22	50
Equity in affiliated companies’ net earnings (losses)	2	(26)	(4)	(6)
Net income from continuing operations	(30)	(61)	(81)	(100)
Net (loss) income from discontinued operations	0	0	0	0
Net income (loss)	(30)	(61)	(81)	(100)
Net income from continuing operations attributable to noncontrolling interests	0	0	0	0
Net income from discontinued operations attributable to noncontrolling interests		0		0
Net income attributable to common stockholders	(30)	(61)	(81)	(100)
Other comprehensive income (loss)	0	0	0	0
Total comprehensive income (loss)	(30)	(61)	(81)	(100)
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Revenues	5,152	3,699	10,005	7,027
Total costs and expenses	3,525	2,990	6,918	5,674
Operating income (loss)	1,627	709	3,087	1,353
Interest expense, net	(92)	(74)	(177)	(145)
Other Nonoperating Income (Expense)	18	(7)	47	2
Income from continuing operations before income taxes and equity in affiliated companies’ net earnings (losses)	1,553	628	2,957	1,210
Provision for income taxes	(512)	(136)	(947)	(282)
Equity in affiliated companies’ net earnings (losses)	(45)	(62)	(79)	(98)
Net income from continuing operations	996	430	1,931	830
Net (loss) income from discontinued operations	(4)	9	(15)	47
Net income (loss)	992	439	1,916	877
Net income from continuing operations attributable to noncontrolling interests	(102)	(46)	(173)	(111)
Net income from discontinued operations attributable to noncontrolling interests		(1)		(4)
Net income attributable to common stockholders	890	392	1,743	762
Other comprehensive income (loss)	11	81	23	92
Total comprehensive income (loss)	$ 901	$ 473	$ 1,766	$ 854