DISPOSITIONS AND ACQUISITIONS (Oil and Gas Operations) (Details) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2018 USD ($) $ / bbl	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) $ / bbl	Dec. 31, 2018 USD ($) $ / bbl	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) $ / bbl	Dec. 31, 2020 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on sales of assets	$ 82	$ 70	$ 45	$ 11	$ 417	$ 208	$ 81
Other current assets	(422)				(655)	(422)
Other assets	(2,172)				(1,885)	(2,172)
Freeport-McMoRan Oil & Gas
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sales					36		80
Net gain (loss) on sales of assets						27
Freeport-McMoRan Oil & Gas | Onshore California
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent receivable					50			$ 150
Contingent consideration asset, per year								$ 50
Other assets	$ (16)				$ (11)	$ (16)
Freeport-McMoRan Oil & Gas | Onshore California | Crude Oil
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent consideration, reference threshold, price per barrel (in us dollars per pound) | $ / bbl	70				70	70		70
Freeport-McMoRan Oil & Gas | Deepwater Gulf of Mexico Interests
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent receivable								$ 150
Other current assets	$ (27)				$ (18)	$ (27)
Other assets	$ (116)				(104)	(116)
Forecast [Member] | Freeport-McMoRan Oil & Gas | Onshore California
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent receivable									$ 50
Corporate And Eliminations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on sales of assets					417	208	81
Corporate And Eliminations [Member] | Gulf of Mexico Shelf and Madden properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on sales of assets					$ 20		$ 49
Corporate And Eliminations [Member] | Onshore California
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on sales of assets						$ 31