Contingencies and Commitments (Unaudited) (Details) shares in Millions, IDR in Trillions	1 Months Ended		3 Months Ended				5 Months Ended	6 Months Ended		9 Months Ended			12 Months Ended
	Nov. 08, 2016 USD ($) shares	May 31, 2016	Sep. 30, 2016 USD ($) shares		Jun. 30, 2016 USD ($) shares		Jan. 11, 2017	Sep. 30, 2016 USD ($) shares		Sep. 30, 2016 USD ($)		Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2016 IDR	May 10, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)
Loss Contingencies [Line Items]
Stock Issued During Period, Shares, New Issues | shares			33.5					28.0
Proceeds from Issuance of Common Stock, Gross			$ 415,000,000					$ 311,000,000		$ 1,500,000,000			$ 2,000,000,000
Gain (Loss) on Contract Termination										(606,000,000)		$ 0
PT Freeport Indonesia [Member]
Loss Contingencies [Line Items]
Assessment By Foreign Government Of Alleged Obligations			231,000,000					231,000,000		231,000,000
Value Added Tax Receivable																	$ 269,000,000
Assessment By Foreign Government of Alleged Obligations, Expressed in Foreign Currency | IDR														IDR 3.0
Income Tax Examination, Penalties Accrued			0					0		0
Royalty Tax [Member] | Cerro Verde [Member]
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss			537,000,000					537,000,000		537,000,000
RelatingtotheperiodDecember2006throughSeptember2011 [Member] | Royalty Tax [Member] | Cerro Verde [Member]
Loss Contingencies [Line Items]
Assessment By Foreign Government Of Alleged Obligations			430,000,000					430,000,000		430,000,000
Tax Year 2014 [Member] | PT Freeport Indonesia [Member]
Loss Contingencies [Line Items]
Assessment By Foreign Government Of Alleged Obligations					$ 156,000,000
Tax Overpayment																	$ 284,000,000
Proceeds from Income Tax Refunds					128,000,000
Disputed Tax Assessments Receivable			152,000,000					152,000,000		152,000,000
Cash and Cash Equivalents [Member] | PT Freeport Indonesia [Member]
Loss Contingencies [Line Items]
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority																$ 196,000,000
Other Liabilities [Member] | PT Freeport Indonesia [Member]
Loss Contingencies [Line Items]
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority																$ 38,000,000
Rowan Companies plc [Member] | Contract Termination [Member]
Loss Contingencies [Line Items]
Cash payments made under settlement agreement					85,000,000
Payable under settlement agreement			130,000,000					130,000,000		130,000,000
Ultra-deepwater Drillship Contracts [Member]
Loss Contingencies [Line Items]
Period, Contingent Consideration		12 months
Unrecorded Unconditional Purchase Obligation, Change of Amount as Result of Variable Components					1,100,000,000
Fair Value, Measurements, Recurring [Member] | Reported Value Measurement [Member]
Loss Contingencies [Line Items]
Loss Contingency, Accrual, Noncurrent			$ 18,000,000	[1]	$ 18,000,000	[2]		$ 18,000,000	[1]	$ 18,000,000	[1]
Noble Drilling LLC [Member] | Maximum [Member] | Ultra-deepwater Drillship Contracts [Member]
Loss Contingencies [Line Items]
Contingent Payments, Contract Termination															$ 75,000,000
Rowan Companies plc [Member] | Maximum [Member] | Ultra-deepwater Drillship Contracts [Member]
Loss Contingencies [Line Items]
Contingent Payments, Contract Termination															$ 30,000,000
Ultra-deepwater Drillship Contracts [Member]
Loss Contingencies [Line Items]
Stock Issued During Period, Shares, New Issues | shares					48.0
Proceeds from Issuance of Common Stock, Gross					$ 540,000,000
Subsequent Event [Member]
Loss Contingencies [Line Items]
Stock Issued During Period, Shares, New Issues | shares	26.3
Proceeds from Issuance of Common Stock, Gross	$ 304,000,000
Subsequent Event [Member] | PT Freeport Indonesia [Member]
Loss Contingencies [Line Items]
Expiration Date, Export Permit							Jan. 11, 2017

[1] Included in accounts payable and accrued liabilities.

[2] Recorded at cost except for debt assumed in acquisitions, which were recorded at fair value at the respective acquisition dates.