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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amount of interest capitalized during the period.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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Amount of long-term debt and capital lease obligations including current maturities.

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Principal amount of long-term debt and capital lease obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Debt (Details) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended				9 Months Ended	12 Months Ended
Debt (Details) $ / shares in Units, $ in Millions	Apr. 04, 2018 USD ($)	Apr. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($) $ / shares	Mar. 31, 2017 USD ($) $ / shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Debt Instruments [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities				$ 11,606				$ 13,117
Less current portion of long-term debt and short-term borrownings				(483)				(1,414)
Long-term Debt and Capital Lease Obligations, Repayments of Principal in Next Twelve Months								1,414
Long-term debt				11,123				11,703
Liabilities, Fair Value Adjustment				93				97
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net				81				85
Senior Notes Issued by FCX [Abstract]
Repayments of Debt				1,633	$ 815
Exchanges and Early Extinguishment of Debt [Abstract]
Interest Costs Incurred				$ 176	$ 195
Dividends declared per share of common stock \| $ / shares				$ 0.05	$ 0
Long-term Debt and Capital Lease Obligations								11,703
Property, Plant and Equipment [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Interest Costs Capitalized				$ 25	$ 28
Oil and Gas Operations Segment [Member] \| Oil and Gas Properties [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Interest Costs Capitalized						$ 0	$ 0
Line of Credit [Member] \| Line of Credit [Member] \| Cerro Verde [Member]
Debt Instruments [Line Items]
Long-term Debt				1,170				1,269
Line of Credit [Member] \| Letter of Credit [Member]
Revolving Credit Facility [Abstract]
Long-term Line of Credit				13
Revolving Credit Facility, Remaining Borrowing Capacity				1,500
Line of Credit [Member] \| Revolving Credit Facility [Member]
Debt Instruments [Line Items]
Long-term Debt				0
Revolving Credit Facility [Abstract]
Revolving Credit Facility, Remaining Borrowing Capacity				3,500
Senior Notes [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Repayments of Lines of Credit				100
Senior Notes [Member] \| 2.375% Senior Notes due March 2018 [Member]
Senior Notes Issued by FCX [Abstract]
Repayments of Debt				1,400
Senior Notes [Member] \| FCX [Member]
Debt Instruments [Line Items]
Long-term Debt, Gross				10,020				11,429
Senior Notes [Member] \| Freeport-McMoRan Oil & Gas
Debt Instruments [Line Items]
Long-term Debt, Gross				54				54
Senior Notes [Member] \| Scenario, Forecast [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Net loss (gain) on exchanges and early extinguishment of debt			$ 10
Debentures [Member] \| Freeport McMoRan Corporation [Member]
Debt Instruments [Line Items]
Long-term Debt, Gross				358				358
Other Debt, Including Capital Leases and Short Term Borrowings [Member]
Debt Instruments [Line Items]
Long-term Debt and Capital Lease Obligations, Including Current Maturities				$ 4				$ 7
Subsequent Event [Member]
Revolving Credit Facility [Abstract]
Debt Instrument, Term		5 years
Subsequent Event [Member] \| Line of Credit [Member] \| Revolving Credit Facility [Member]
Revolving Credit Facility [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity		$ 3,500
Exchanges and Early Extinguishment of Debt [Abstract]
Amount of revolving credit facility available to subsidiary		$ 500
Subsequent Event [Member] \| Senior Notes [Member] \| Freeport-McMoRan Oil & Gas
Exchanges and Early Extinguishment of Debt [Abstract]
Extinguishment Of Debt, Redemption Value	$ 454
Subsequent Event [Member] \| Senior Notes [Member] \| Freeport-McMoRan Oil & Gas \| 6.75% Senior Notes due 2022 [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Extinguishment Of Debt, Redemption Value	404
Subsequent Event [Member] \| Senior Notes [Member] \| Freeport-McMoRan Oil & Gas \| 6.875% Senior Notes due 2023 [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Extinguishment Of Debt, Redemption Value	$ 50
Subsequent Event [Member] \| Maximum [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
Debt Instrument, Covenant Compliance, Leverage Ratio		3.75
Subsequent Event [Member] \| Minimum [Member]
Exchanges and Early Extinguishment of Debt [Abstract]
DebtInstrumentCovenantComplianceCoverageRatio		2.25