Guarantor Financial Statements (Unaudited) Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
ASSETS
Current assets, other than assets held-for-sale	$ 8,347		$ 10,720
Property, plant, equipment and mine development costs, net	29,330		28,010
Investments in consolidated subsidiaries	0		0
Other assets	3,266		3,486
Total assets	40,943		42,216	$ 37,749
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	3,381		3,329
Long-term debt, less current portion	9,915		11,124
Deferred income taxes	4,245		4,032
Environmental and asset retirement obligations, less current portion	3,558		3,609
Investments in consolidated subsidiaries	0		0
Other liabilities	2,302		2,230
Total liabilities	23,401		24,324
Equity:
Stockholders' equity	9,444		9,798
Noncontrolling interests	8,098		8,094
Total equity	17,542	$ 17,817	17,892	$ 13,454	$ 12,842	$ 11,296
Total liabilities and equity	40,943		42,216
Eliminations [Member]
ASSETS
Current assets, other than assets held-for-sale	(603)		(585)
Property, plant, equipment and mine development costs, net	7		0
Investments in consolidated subsidiaries	(17,523)		(19,064)
Other assets	(1,099)		(635)
Total assets	(19,218)		(20,284)
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	(635)		(617)
Long-term debt, less current portion	(11,903)		(11,103)
Deferred income taxes	0		0
Environmental and asset retirement obligations, less current portion	0		0
Investments in consolidated subsidiaries	(11,467)		(11,091)
Other liabilities	(3,488)		(3,486)
Total liabilities	(27,493)		(26,297)
Equity:
Stockholders' equity	2,809		601
Noncontrolling interests	5,466		5,412
Total equity	8,275		6,013
Total liabilities and equity	(19,218)		(20,284)
FCX Issuer [Member] | Reportable Legal Entities [Member]
ASSETS
Current assets, other than assets held-for-sale	46		309
Property, plant, equipment and mine development costs, net	18		19
Investments in consolidated subsidiaries	17,523		19,064
Other assets	1,340		880
Total assets	18,927		20,272
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	312		245
Long-term debt, less current portion	8,600		9,594
Deferred income taxes	498		524
Environmental and asset retirement obligations, less current portion	0		0
Investments in consolidated subsidiaries	0		0
Other liabilities	73		111
Total liabilities	9,483		10,474
Equity:
Stockholders' equity	9,444		9,798
Noncontrolling interests	0		0
Total equity	9,444		9,798
Total liabilities and equity	18,927		20,272
FM O&G LLC Guarantor [Member] | Reportable Legal Entities [Member]
ASSETS
Current assets, other than assets held-for-sale	606		620
Property, plant, equipment and mine development costs, net	5		7
Investments in consolidated subsidiaries	0		0
Other assets	17		23
Total assets	628		650
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	42		34
Long-term debt, less current portion	7,215		6,984
Deferred income taxes	0		0
Environmental and asset retirement obligations, less current portion	237		227
Investments in consolidated subsidiaries	630		578
Other liabilities	3,341		3,340
Total liabilities	11,465		11,163
Equity:
Stockholders' equity	(10,837)		(10,513)
Noncontrolling interests	0		0
Total equity	(10,837)		(10,513)
Total liabilities and equity	628		650
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
ASSETS
Current assets, other than assets held-for-sale	8,298		10,376
Property, plant, equipment and mine development costs, net	29,300		27,984
Investments in consolidated subsidiaries	0		0
Other assets	3,008		3,218
Total assets	40,606		41,578
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	3,662		3,667
Long-term debt, less current portion	6,003		5,649
Deferred income taxes	3,747		3,508
Environmental and asset retirement obligations, less current portion	3,321		3,382
Investments in consolidated subsidiaries	10,837		10,513
Other liabilities	2,376		2,265
Total liabilities	29,946		28,984
Equity:
Stockholders' equity	8,028		9,912
Noncontrolling interests	2,632		2,682
Total equity	10,660		12,594
Total liabilities and equity	$ 40,606		$ 41,578