Contingencies and Commitments (Unaudited)	6 Months Ended
Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	CONTINGENCIES AND COMMITMENTS Environmental Cyprus Tohono Cyprus Tohono, a wholly owned subsidiary of FMC, had historical mining operations in south central Arizona, and groundwater issues at the site are expected to require remediation. FCX increased its recorded environmental obligation for this contingency by $44 million with a corresponding charge to operating income in second-quarter 2018 to reflect an updated assessment of remediation alternatives. Litigation There were no significant updates to previously reported legal proceedings included in Note 12 of FCX’s annual report on Form 10-K for the year ended December 31, 2017, other than the matter below, which was also disclosed in Note 8 of FCX’s quarterly report on Form 10-Q for the quarter ended March 31, 2018. On April 1, 2016, a purported class action titled David Garcia v. Freeport-McMoRan Oil & Gas LLC was filed in the Superior Court of the State of California for the County of Santa Barbara (Case No. 16CV01305) against FM O&G LLC, an indirect wholly owned subsidiary of FCX. A former FM O&G LLC employee filed the case, which alleges violations of various California employment laws and seeks relief for past wages, overtime, penalties, interest and attorney’s fees. The primary issue underlying the claims is whether compensation must be paid to non-exempt shift workers on platforms located offshore California on the outer-continental shelf for sleep time and other non-working time. In June 2016, FM O&G LLC removed the case to the U.S. District Court for the Central District of California, Santa Barbara (the District Court). In September 2016, the court dismissed the complaint on the grounds that all four FM O&G LLC platforms potentially involved are located in federal waters, that federal law, not state law, applies, and that federal law does not require an employer to compensate for non-work time. In October 2016, the plaintiff appealed the dismissal to the U.S. Court of Appeals for the Ninth Circuit. In June 2017, the Ninth Circuit stayed the Garcia case pending its decision in another case involving essentially the same legal issues, titled Newton v. Parker Drilling Management Services, Ltd. In February 2018, a three-judge panel of the Ninth Circuit ruled in favor of the plaintiffs in the Newton case. Because that decision conflicts with longstanding precedent in the Fifth Circuit and could set a precedent that will result in a reversal of the dismissal in the Garcia case, FM O&G LLC and others filed amicus briefs in April 2018 in support of Parker Drilling’s petition for an en banc rehearing in the Newton case. The Ninth Circuit denied that request on April 27, 2018, but modified its original opinion noting that the question of whether the Ninth Circuit’s holding should be applied retrospectively is reserved for the District Court’s consideration on remand. On May 16, 2018, the Ninth Circuit granted Parker Drilling’s motion to stay further proceedings in the District Court pending the possible filing of a petition for review by the U.S. Supreme Court, which would be required to be filed by late August 2018. On May 29, 2018, the Ninth Circuit also stayed further proceedings in Garcia pending the U.S. Supreme Court’s consideration of the petition for review in Newton v. Parker Drilling. The amount of the exposure in Garcia is uncertain because FM O&G LLC has potential defenses to the claims even if state law would be applied; however, absent success on those defenses, FCX estimates that the exposure could be in the range of approximately $50 million to $80 million if California wage and hour law is applied retroactively to FM O&G LLC’s operations offshore California. FCX has not established a reserve for this contingency because it believes that its legal position is correct and does not believe a loss is probable. FCX intends to vigorously defend this matter. Tax and Other Matters Cerro Verde Royalty Dispute and Other Peru Tax Matters During second-quarter 2018, there were no significant updates to the Cerro Verde royalty dispute and other Peru tax matters included in Note 12 of FCX’s annual report on Form 10-K for the year ended December 31, 2017. Indonesia Tax Matters There were no significant updates to previously reported Indonesia tax matters included in Note 12 of FCX’s annual report on Form 10-K for the year ended December 31, 2017, other than the matter below, which was also updated in Note 8 of FCX’s quarterly report on Form 10-Q for the quarter ended March 31, 2018. PT-FI received assessments from the local regional tax authority in Papua, Indonesia, for additional taxes and penalties related to surface water taxes for the period from January 2011 through June 2018. PT-FI has filed or will file appeals of these assessments with the Indonesia Tax Court. During the first half of 2018, the Indonesia Tax Court ruled partially in favor of PT-FI with respect to assessments for the period January 2016 through April 2016 by reducing these assessments that amounted to $20 million, including penalties, to $12 million, including penalties (based on the exchange rate at June 30, 2018), or an approximate 40 percent reduction. Hearings in the Indonesia Tax Court related to assessments for the period from May 2016 through September 2016 have concluded with no decisions issued, and hearings related to assessments for the period from October 2016 through April 2017 are currently underway. During 2017, PT-FI filed reconsideration request petitions to the Indonesia Supreme Court with respect to assessments for the period from January 2011 through December 2015; and in second-quarter 2018, filed reconsideration request petitions with respect to the Indonesia Tax Court decisions related to the assessments for the period from January 2016 through April 2016. In second-quarter 2018, the Indonesia Supreme Court issued favorable decisions relating to surface water tax assessments for the period January 2011 through July 2015. The Indonesia Supreme Court ruling concluded that PT-FI and the Indonesian government are bound by PT-FI’s Contract of Work (COW), which is lex specialis, and prevails as the law for the parties to the COW that should be carried out in good faith. As a result, FCX estimates the total amount of the assessments, including penalties, (based on the exchange rate at June 30, 2018) for the period from August 2015 through June 2018 totals $169 million, including $85 million in penalties. As of June 30, 2018, no charges have been recorded for these assessments because PT-FI believes its COW exempts it from these payments. As of August 8, 2018, PT-FI has not paid and does not intend to pay these assessments. Indonesia Mining Contract. The following is the latest information related to PT-FI’s COW (refer to Note 13 of FCX’s annual report on Form 10-K for the year ended December 31, 2017, for further discussion). In October 2017, Indonesia’s Ministry of Environment and Forestry (the Ministry) notified PT-FI of administrative sanctions related to certain activities the Ministry indicated are not reflected in PT-FI’s environmental permit. The Ministry also notified PT-FI that certain operational activities were inconsistent with factors set forth in PT-FI’s environmental permitting studies and that additional monitoring and improvements need to be undertaken related to air quality, water drainage, treatment and handling of certain wastes, and tailings management. PT-FI has been engaged in a process to update its permits through submissions and dialogue with the Ministry that began in late 2014, and PT-FI believes that it has submitted the required documentation to update such permits. In April 2018, the Ministry issued decrees imposing unattainable environmental standards related to PT-FI’s controlled riverine tailings management system that must be complied with by October 2018. The decrees, which PT-FI believes are contrary to the Indonesian government’s obligations under PT-FI’s COW, conflict with PT-FI’s approved environmental management programs and existing environmental permits. If these unattainable environmental standards are not modified or delayed, PT-FI could be adversely affected, including possible shutdown of its operations. PT-FI is currently engaged in constructive discussions with the Ministry in working toward a resolution of these issues. PT-FI and the Indonesian government have been engaged in negotiation and documentation of a special mining license (IUPK) and accompanying documentation for assurances on legal and fiscal terms to provide PT-FI with long-term mining rights through 2041. In addition, the IUPK would provide that PT-FI construct a smelter within five years of reaching definitive agreements and include agreement for the divestment of 51 percent of the project area interests to Indonesian participants at fair market value. In late 2017, the Indonesian government (including the regional government of Papua Province and Mimika Regency) and PT Indonesia Asahan Aluminium (Persero) (Inalum), a state-owned enterprise, which leads the Indonesian government’s consortium of investors, formed a special purpose company to acquire Grasberg project area interests. Inalum is wholly owned by the Indonesian government and currently holds 9.36 percent of PT-FI’s outstanding common stock. In July 2018, FCX and PT-FI entered into a Heads of Agreement with Inalum and PT-FI’s joint venture partner Rio Tinto. Under the terms of the non-binding agreement, Inalum would acquire for aggregate cash consideration of $3.85 billion all of Rio Tinto's interests associated with its joint venture with PT-FI (Joint Venture) and all of FCX's interests in PT Indocopper Investama, which owns 9.36 percent of PT-FI. Inalum would contribute the Rio Tinto interests to PT-FI, which would expand PT-FI’s asset base, in exchange for a 40 percent share ownership in PT-FI, pursuant to arrangements that would enable FCX and existing PT-FI shareholders to retain the economics of the revenue and cost sharing arrangements under the Joint Venture. Following completion of the transaction, Inalum's share ownership would approximate 51 percent of PT-FI (subject to an agreement between shareholders to replicate the Joint Venture economics) and FCX's ownership would approximate 49 percent. At closing, Rio Tinto would receive $3.5 billion and FCX would receive $350 million in cash proceeds from Inalum. In addition, Rio Tinto would forego in favor of FCX an amount equivalent to Rio Tinto's share of Joint Venture cash flows since January 1, 2018, through closing. Following completion of the ownership restructuring, FCX does not expect its economic exposure to PT-FI to change significantly. FCX expects its share of future cash flows of the expanded PT-FI asset base, combined with the cash proceeds received in the transaction, to be comparable to its existing share of future cash flows under the current Joint Venture arrangement. FCX would also continue to manage the operations of PT-FI. The transaction, which is expected to close during the second half of 2018, is subject to the negotiation and documentation of definitive agreements, including purchase and sale agreements, the extension and stability of PT-FI's long-term mining rights through 2041 in a form acceptable to FCX and Inalum, a shareholders’ agreement between FCX and Inalum providing for continuity of FCX’s management of PT-FI’s operations and addressing governance arrangements, and resolution of environmental regulatory matters pending before the Ministry satisfactory to the Indonesian government, FCX and Inalum. The terms of these agreements will be subject to approval by the FCX Board, and will require modification or revocation of current regulations and the implementation of new regulations by the Indonesian government. FCX cannot currently predict whether there will be any material accounting and tax impacts associated with the transaction. PT-FI’s export license is effective through February 15, 2019. In July 2018, PT-FI’s temporary IUPK was extended to August 31, 2018, and PT-FI will continue to seek extensions to its temporary IUPK until definitive agreements are complete. On February 28, 2018, PT Smelting (PT-FI’s 25 percent-owned smelter and refinery in Indonesia) received an extension of its anode slimes export license through February 26, 2019. FCX cannot predict whether PT-FI will be successful in reaching satisfactory definitive agreements on the terms of its long-term mining rights. Until definitive agreements are reached, PT-FI has reserved all rights under its COW, including pursuing arbitration under the dispute resolution procedures.

CONTINGENCIES AND COMMITMENTS

Environmental

Cyprus Tohono

Cyprus Tohono, a wholly owned subsidiary of FMC, had historical mining operations in south central Arizona, and groundwater issues at the site are expected to require remediation. FCX increased its recorded environmental obligation for this contingency by $44 million with a corresponding charge to operating income in second-quarter 2018 to reflect an updated assessment of remediation alternatives.

Litigation

There were no significant updates to previously reported legal proceedings included in Note 12 of FCX’s annual report on Form 10-K for the year ended December 31, 2017, other than the matter below, which was also disclosed in Note 8 of FCX’s quarterly report on Form 10-Q for the quarter ended March 31, 2018.

On April 1, 2016, a purported class action titled David Garcia v. Freeport-McMoRan Oil & Gas LLC was filed in the Superior Court of the State of California for the County of Santa Barbara (Case No. 16CV01305) against FM O&G LLC, an indirect wholly owned subsidiary of FCX. A former FM O&G LLC employee filed the case, which alleges violations of various California employment laws and seeks relief for past wages, overtime, penalties, interest and attorney’s fees. The primary issue underlying the claims is whether compensation must be paid to non-exempt shift workers on platforms located offshore California on the outer-continental shelf for sleep time and other non-working time. In June 2016, FM O&G LLC removed the case to the U.S. District Court for the Central District of California, Santa Barbara (the District Court). In September 2016, the court dismissed the complaint on the grounds that all four FM O&G LLC platforms potentially involved are located in federal waters, that federal law, not state law, applies, and that federal law does not require an employer to compensate for non-work time. In October 2016, the plaintiff appealed the dismissal to the U.S. Court of Appeals for the Ninth Circuit. In June 2017, the Ninth Circuit stayed the Garcia case pending its decision in another case involving essentially the same legal issues, titled Newton v. Parker Drilling Management Services, Ltd. In February 2018, a three-judge panel of the Ninth Circuit ruled in favor of the plaintiffs in the Newton case. Because that decision conflicts with longstanding precedent in the Fifth Circuit and could set a precedent that will result in a reversal of the dismissal in the Garcia case, FM O&G LLC and others filed amicus briefs in April 2018 in support of Parker Drilling’s petition for an en banc rehearing in the Newton case. The Ninth Circuit denied that request on April 27, 2018, but modified its original opinion noting that the question of whether the Ninth Circuit’s holding should be applied retrospectively is reserved for the District Court’s consideration on remand. On May 16, 2018, the Ninth Circuit granted Parker Drilling’s motion to stay further proceedings in the District Court pending the possible filing of a petition for review by the U.S. Supreme Court, which would be required to be filed by late August 2018. On May 29, 2018, the Ninth Circuit also stayed further proceedings in Garcia pending the U.S. Supreme Court’s consideration of the petition for review in Newton v. Parker Drilling.

The amount of the exposure in Garcia is uncertain because FM O&G LLC has potential defenses to the claims even if state law would be applied; however, absent success on those defenses, FCX estimates that the exposure could be in the range of approximately $50 million to $80 million if California wage and hour law is applied retroactively to FM O&G LLC’s operations offshore California. FCX has not established a reserve for this contingency because it believes that its legal position is correct and does not believe a loss is probable. FCX intends to vigorously defend this matter.

Tax and Other Matters

Cerro Verde Royalty Dispute and Other Peru Tax Matters

During second-quarter 2018, there were no significant updates to the Cerro Verde royalty dispute and other Peru tax matters included in Note 12 of FCX’s annual report on Form 10-K for the year ended December 31, 2017.

Indonesia Tax Matters

There were no significant updates to previously reported Indonesia tax matters included in Note 12 of FCX’s annual report on Form 10-K for the year ended December 31, 2017, other than the matter below, which was also updated in Note 8 of FCX’s quarterly report on Form 10-Q for the quarter ended March 31, 2018.

PT-FI received assessments from the local regional tax authority in Papua, Indonesia, for additional taxes and penalties related to surface water taxes for the period from January 2011 through June 2018. PT-FI has filed or will file appeals of these assessments with the Indonesia Tax Court. During the first half of 2018, the Indonesia Tax Court ruled partially in favor of PT-FI with respect to assessments for the period January 2016 through April 2016 by reducing these assessments that amounted to $20 million, including penalties, to $12 million, including penalties (based on the exchange rate at June 30, 2018), or an approximate 40 percent reduction. Hearings in the Indonesia Tax Court related to assessments for the period from May 2016 through September 2016 have concluded with no decisions issued, and hearings related to assessments for the period from October 2016 through April 2017 are currently underway.

During 2017, PT-FI filed reconsideration request petitions to the Indonesia Supreme Court with respect to assessments for the period from January 2011 through December 2015; and in second-quarter 2018, filed reconsideration request petitions with respect to the Indonesia Tax Court decisions related to the assessments for the period from January 2016 through April 2016. In second-quarter 2018, the Indonesia Supreme Court issued favorable decisions relating to surface water tax assessments for the period January 2011 through July 2015. The Indonesia Supreme Court ruling concluded that PT-FI and the Indonesian government are bound by PT-FI’s Contract of Work (COW), which is lex specialis, and prevails as the law for the parties to the COW that should be carried out in good faith. As a result, FCX estimates the total amount of the assessments, including penalties, (based on the exchange rate at June 30, 2018) for the period from August 2015 through June 2018 totals $169 million, including $85 million in penalties. As of June 30, 2018, no charges have been recorded for these assessments because PT-FI believes its COW exempts it from these payments. As of August 8, 2018, PT-FI has not paid and does not intend to pay these assessments.

Indonesia Mining Contract. The following is the latest information related to PT-FI’s COW (refer to Note 13 of FCX’s annual report on Form 10-K for the year ended December 31, 2017, for further discussion).

In October 2017, Indonesia’s Ministry of Environment and Forestry (the Ministry) notified PT-FI of administrative sanctions related to certain activities the Ministry indicated are not reflected in PT-FI’s environmental permit. The Ministry also notified PT-FI that certain operational activities were inconsistent with factors set forth in PT-FI’s environmental permitting studies and that additional monitoring and improvements need to be undertaken related to air quality, water drainage, treatment and handling of certain wastes, and tailings management. PT-FI has been engaged in a process to update its permits through submissions and dialogue with the Ministry that began in late 2014, and PT-FI believes that it has submitted the required documentation to update such permits. In April 2018, the Ministry issued decrees imposing unattainable environmental standards related to PT-FI’s controlled riverine tailings management system that must be complied with by October 2018. The decrees, which PT-FI believes are contrary to the Indonesian government’s obligations under PT-FI’s COW, conflict with PT-FI’s approved environmental management programs and existing environmental permits. If these unattainable environmental standards are not modified or delayed, PT-FI could be adversely affected, including possible shutdown of its operations. PT-FI is currently engaged in constructive discussions with the Ministry in working toward a resolution of these issues.

PT-FI and the Indonesian government have been engaged in negotiation and documentation of a special mining license (IUPK) and accompanying documentation for assurances on legal and fiscal terms to provide PT-FI with long-term mining rights through 2041. In addition, the IUPK would provide that PT-FI construct a smelter within five years of reaching definitive agreements and include agreement for the divestment of 51 percent of the project area interests to Indonesian participants at fair market value.

In late 2017, the Indonesian government (including the regional government of Papua Province and Mimika Regency) and PT Indonesia Asahan Aluminium (Persero) (Inalum), a state-owned enterprise, which leads the Indonesian government’s consortium of investors, formed a special purpose company to acquire Grasberg project area interests. Inalum is wholly owned by the Indonesian government and currently holds 9.36 percent of PT-FI’s outstanding common stock.

In July 2018, FCX and PT-FI entered into a Heads of Agreement with Inalum and PT-FI’s joint venture partner Rio Tinto. Under the terms of the non-binding agreement, Inalum would acquire for aggregate cash consideration of $3.85 billion all of Rio Tinto's interests associated with its joint venture with PT-FI (Joint Venture) and all of FCX's interests in PT Indocopper Investama, which owns 9.36 percent of PT-FI.

Inalum would contribute the Rio Tinto interests to PT-FI, which would expand PT-FI’s asset base, in exchange for a 40 percent share ownership in PT-FI, pursuant to arrangements that would enable FCX and existing PT-FI shareholders to retain the economics of the revenue and cost sharing arrangements under the Joint Venture. Following completion of the transaction, Inalum's share ownership would approximate 51 percent of PT-FI (subject to an agreement between shareholders to replicate the Joint Venture economics) and FCX's ownership would approximate 49 percent.

At closing, Rio Tinto would receive $3.5 billion and FCX would receive $350 million in cash proceeds from Inalum. In addition, Rio Tinto would forego in favor of FCX an amount equivalent to Rio Tinto's share of Joint Venture cash flows since January 1, 2018, through closing.

Following completion of the ownership restructuring, FCX does not expect its economic exposure to PT-FI to change significantly. FCX expects its share of future cash flows of the expanded PT-FI asset base, combined with the cash proceeds received in the transaction, to be comparable to its existing share of future cash flows under the current Joint Venture arrangement. FCX would also continue to manage the operations of PT-FI.

The transaction, which is expected to close during the second half of 2018, is subject to the negotiation and documentation of definitive agreements, including purchase and sale agreements, the extension and stability of PT-FI's long-term mining rights through 2041 in a form acceptable to FCX and Inalum, a shareholders’ agreement between FCX and Inalum providing for continuity of FCX’s management of PT-FI’s operations and addressing governance arrangements, and resolution of environmental regulatory matters pending before the Ministry satisfactory to the Indonesian government, FCX and Inalum. The terms of these agreements will be subject to approval by the FCX Board, and will require modification or revocation of current regulations and the implementation of new regulations by the Indonesian government. FCX cannot currently predict whether there will be any material accounting and tax impacts associated with the transaction.

PT-FI’s export license is effective through February 15, 2019. In July 2018, PT-FI’s temporary IUPK was extended to August 31, 2018, and PT-FI will continue to seek extensions to its temporary IUPK until definitive agreements are complete. On February 28, 2018, PT Smelting (PT-FI’s 25 percent-owned smelter and refinery in Indonesia) received an extension of its anode slimes export license through February 26, 2019.

FCX cannot predict whether PT-FI will be successful in reaching satisfactory definitive agreements on the terms of its long-term mining rights. Until definitive agreements are reached, PT-FI has reserved all rights under its COW, including pursuing arbitration under the dispute resolution procedures.