Guarantor Financial Statements (Unaudited) Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
ASSETS
Current assets, other than assets held-for-sale	$ 10,106	$ 10,779
Property, plant, equipment and mine development costs, net	22,792	22,844
Investments in consolidated subsidiaries	0	0
Other assets	3,739	3,679
Total assets	36,637	37,302	$ 36,576
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	4,344	5,038
Long-term debt, less current portion	11,123	11,703
Deferred income taxes	3,642	3,622
Environmental and asset retirement obligations, less current portion	3,630	3,631
Investments in consolidated subsidiaries	0	0
Other liabilities	1,972	2,012
Total liabilities	24,711	26,006
Equity:
Stockholders' equity	8,656	7,977
Noncontrolling interests	3,270	3,319
Total equity	11,926	11,296
Total liabilities and equity	36,637	37,302
Eliminations [Member]
ASSETS
Current assets, other than assets held-for-sale	(1,164)	(790)
Property, plant, equipment and mine development costs, net	(9)	(10)
Investments in consolidated subsidiaries	(18,668)	(19,570)
Other assets	(111)	(491)
Total assets	(19,952)	(20,861)
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	(1,225)	(938)
Long-term debt, less current portion	(10,058)	(10,270)
Deferred income taxes	0	0
Environmental and asset retirement obligations, less current portion	0	0
Investments in consolidated subsidiaries	(11,198)	(11,250)
Other liabilities	(3,486)	(3,488)
Total liabilities	(25,967)	(25,946)
Equity:
Stockholders' equity	5,437	4,480
Noncontrolling interests	578	605
Total equity	6,015	5,085
Total liabilities and equity	(19,952)	(20,861)
FCX Issuer [Member] | Reportable Legal Entities [Member]
ASSETS
Current assets, other than assets held-for-sale	544	75
Property, plant, equipment and mine development costs, net	14	14
Investments in consolidated subsidiaries	18,668	19,570
Other assets	561	943
Total assets	19,787	20,602
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	621	1,683
Long-term debt, less current portion	9,594	10,021
Deferred income taxes	745	748
Environmental and asset retirement obligations, less current portion	0	0
Investments in consolidated subsidiaries	0	0
Other liabilities	171	173
Total liabilities	11,131	12,625
Equity:
Stockholders' equity	8,656	7,977
Noncontrolling interests	0	0
Total equity	8,656	7,977
Total liabilities and equity	19,787	20,602
FM O&G LLC Guarantor [Member] | Reportable Legal Entities [Member]
ASSETS
Current assets, other than assets held-for-sale	714	671
Property, plant, equipment and mine development costs, net	7	11
Investments in consolidated subsidiaries	0	0
Other assets	34	48
Total assets	755	730
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	117	220
Long-term debt, less current portion	6,574	6,512
Deferred income taxes	0	0
Environmental and asset retirement obligations, less current portion	203	201
Investments in consolidated subsidiaries	860	853
Other liabilities	3,339	3,340
Total liabilities	11,093	11,126
Equity:
Stockholders' equity	(10,338)	(10,396)
Noncontrolling interests	0	0
Total equity	(10,338)	(10,396)
Total liabilities and equity	755	730
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
ASSETS
Current assets, other than assets held-for-sale	10,012	10,823
Property, plant, equipment and mine development costs, net	22,780	22,829
Investments in consolidated subsidiaries	0	0
Other assets	3,255	3,179
Total assets	36,047	36,831
LIABILITIES AND EQUITY
Current liabilities, other than liabilities held for sale	4,831	4,073
Long-term debt, less current portion	5,013	5,440
Deferred income taxes	2,897	2,874
Environmental and asset retirement obligations, less current portion	3,427	3,430
Investments in consolidated subsidiaries	10,338	10,397
Other liabilities	1,948	1,987
Total liabilities	28,454	28,201
Equity:
Stockholders' equity	4,901	5,916
Noncontrolling interests	2,692	2,714
Total equity	7,593	8,630
Total liabilities and equity	$ 36,047	$ 36,831