Business Segments (Segment Reporting) (Details) lb in Millions, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2020 lb $ / lb	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of Operating Segments | segment				4
Deferred Intercompany Profit, Percentage				25.00%
Revenues		$ 3,851	$ 3,153	$ 9,703	$ 10,491
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(2,465)	(2,670)	(7,404)	(8,599)
Cost, Depreciation, Amortization and Depletion		394	322	1,093	1,021
Metals inventory adjustments		9	41	92	100
Selling, general and administrative expenses		(72)	(101)	(273)	(300)
Mining exploration and research expenses		8	25	42	83
Environmental obligations and shutdown costs		21	20	58	85
Net gain on sales of assets		2	12	13	(13)
Operating income (loss)		880	(38)	728	316
Interest expense, net		120	123	362	401
Provision for (benefit from) income taxes		297	91	333	181
Total assets		41,099	40,943	41,099	40,943	$ 40,809
Capital expenditures		436	666	1,573	1,917
Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues		16	80	61	272
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(768)	(896)	(2,415)	(2,463)
Cost, Depreciation, Amortization and Depletion		91	91	272	261
Metals inventory adjustments		(4)	38	52	39
Selling, general and administrative expenses		(1)	(2)	(3)	(4)
Mining exploration and research expenses		0	0	2	1
Environmental obligations and shutdown costs		(3)	0	(3)	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		384	113	469	526
Interest expense, net		0	1	2	3
Provision for (benefit from) income taxes		0	0	0	0
Total assets		7,791	7,948	7,791	7,948
Capital expenditures		66	224	398	641
Operating Segments | South America
Segment Reporting Information [Line Items]
Revenues		740	621	1,791	2,136
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(477)	(528)	(1,449)	(1,648)
Cost, Depreciation, Amortization and Depletion		105	109	315	342
Metals inventory adjustments		0	2	3	2
Selling, general and administrative expenses		(2)	(2)	(5)	(6)
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		222	45	175	400
Interest expense, net		21	25	69	79
Provision for (benefit from) income taxes		109	33	76	149
Total assets		10,209	10,223	10,209	10,223
Capital expenditures		31	68	156	176
Corporate And Eliminations
Segment Reporting Information [Line Items]
Revenues		266	423	780	1,350
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		1,034	770	2,676	2,158
Cost, Depreciation, Amortization and Depletion		21	20	51	59
Metals inventory adjustments		8	0	26	58
Selling, general and administrative expenses		(39)	(61)	(169)	(184)
Mining exploration and research expenses		8	25	40	82
Environmental obligations and shutdown costs		24	20	60	85
Net gain on sales of assets		2	12	13	(13)
Operating income (loss)		(145)	(168)	(457)	(601)
Interest expense, net		99	91	285	300
Provision for (benefit from) income taxes		(23)	67	(46)	39
Total assets		3,103	3,623	3,103	3,623
Capital expenditures		4	25	24	76
Intersegment
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Intersegment | North America
Segment Reporting Information [Line Items]
Revenues		1,221	1,060	3,149	3,022
Intersegment | South America
Segment Reporting Information [Line Items]
Revenues		66	65	156	262
PT Smelting | Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues		506	475	1,300	1,400
Morenci [Member] | Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues		4	61	26	89
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(308)	(377)	(1,005)	(1,020)
Cost, Depreciation, Amortization and Depletion		42	45	129	128
Metals inventory adjustments		0	1	4	1
Selling, general and administrative expenses		(1)	(1)	(2)	(2)
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		237	99	359	349
Interest expense, net		0	0	2	2
Provision for (benefit from) income taxes		0	0	0	0
Total assets		2,654	2,943	2,654	2,943
Capital expenditures		21	61	92	172
Morenci [Member] | Intersegment | North America
Segment Reporting Information [Line Items]
Revenues		584	462	1,473	1,411
Bagdad [Member] | Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(123)	(140)	(367)	(388)
Cost, Depreciation, Amortization and Depletion		14	12	41	33
Metals inventory adjustments		0	0	0	0
Selling, general and administrative expenses		0	(1)	0	(1)
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		70	56	124	169
Interest expense, net		0	0		0
Provision for (benefit from) income taxes		0	0	0	0
Total assets		785	769	785	769
Capital expenditures		7	42	44	100
Bagdad [Member] | Operating Segments | Bagdad [Member]
Segment Reporting Information [Line Items]
Interest expense, net				0
Bagdad [Member] | Intersegment | North America
Segment Reporting Information [Line Items]
Revenues		207	209	532	591
Other Mines North America Copper Mines Segment [Member] | Operating Segments | North America
Segment Reporting Information [Line Items]
Metals inventory adjustments			37		38
Other Individually Immaterial Operating Segments [Member] | Operating Segments | North America
Segment Reporting Information [Line Items]
Revenues		12	19	35	183
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(337)	(379)	(1,043)	(1,055)
Cost, Depreciation, Amortization and Depletion		35	34	102	100
Metals inventory adjustments		(4)		48
Selling, general and administrative expenses		0	0	(1)	(1)
Mining exploration and research expenses		0	0	2	1
Environmental obligations and shutdown costs		(3)	0	(3)	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		77	(42)	(14)	8
Interest expense, net		0	1	0	1
Provision for (benefit from) income taxes		0	0	0	0
Total assets		4,352	4,236	4,352	4,236
Capital expenditures		38	121	262	369
Other Individually Immaterial Operating Segments [Member] | Operating Segments | South America
Segment Reporting Information [Line Items]
Revenues		108	117	312	343
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(83)	(111)	(297)	(337)
Cost, Depreciation, Amortization and Depletion		13	16	42	48
Metals inventory adjustments		0	0	3	0
Selling, general and administrative expenses		0	0	0	0
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		12	(10)	(30)	(42)
Interest expense, net		0	0	0	0
Provision for (benefit from) income taxes		4	4	(6)	(10)
Total assets		1,640	1,723	1,640	1,723
Capital expenditures		5	7	40	16
Other Individually Immaterial Operating Segments [Member] | Intersegment | North America
Segment Reporting Information [Line Items]
Revenues		430	389	1,144	1,020
Other Individually Immaterial Operating Segments [Member] | Intersegment | South America
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Cerro Verde [Member] | Operating Segments | South America
Segment Reporting Information [Line Items]
Revenues		632	504	1,479	1,793
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(394)	(417)	(1,152)	(1,311)
Cost, Depreciation, Amortization and Depletion		92	93	273	294
Metals inventory adjustments		0	2	0	2
Selling, general and administrative expenses		(2)	(2)	(5)	(6)
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		210	55	205	442
Interest expense, net		21	25	69	79
Provision for (benefit from) income taxes		105	29	82	159
Total assets		8,569	8,500	8,569	8,500
Capital expenditures		26	61	116	160
Cerro Verde [Member] | Intersegment | South America
Segment Reporting Information [Line Items]
Revenues		66	65	156	262
Grasberg Segment [Member]
Segment Reporting Information [Line Items]
Capital expenditures				959	992
Grasberg Segment [Member] | Operating Segments | Indonesia
Segment Reporting Information [Line Items]
Revenues		1,023	488	2,151	1,776
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(409)	(399)	(1,130)	(1,509)
Cost, Depreciation, Amortization and Depletion		150	77	375	281
Metals inventory adjustments		0	0	0	0
Selling, general and administrative expenses		(25)	(31)	(81)	(91)
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		442	(19)	603	(48)
Interest expense, net		0	1	2	2
Provision for (benefit from) income taxes		211	(8)	302	(9)
Total assets		17,098	16,447	17,098	16,447
Capital expenditures		325	334	959	992
Grasberg Segment [Member] | Intersegment | Indonesia
Segment Reporting Information [Line Items]
Revenues		3	0	38	57
Molybdenum
Segment Reporting Information [Line Items]
Capital expenditures				14	11
Molybdenum | Operating Segments
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(51)	(85)	(178)	(234)
Cost, Depreciation, Amortization and Depletion		13	16	44	50
Metals inventory adjustments		3	1	8	1
Selling, general and administrative expenses		0	0	0	0
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		(25)	(12)	(59)	5
Interest expense, net		0	0	0	0
Provision for (benefit from) income taxes		0	0	0	0
Total assets		1,770	1,786	1,770	1,786
Capital expenditures		3	5	14	11
Molybdenum | Intersegment
Segment Reporting Information [Line Items]
Revenues		42	90	171	290
Rod and Refining Segment [Member] | Operating Segments
Segment Reporting Information [Line Items]
Revenues		1,270	1,104	3,491	3,403
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(1,272)	(1,111)	(3,529)	(3,415)
Cost, Depreciation, Amortization and Depletion		6	2	14	7
Metals inventory adjustments		2	0	3	0
Selling, general and administrative expenses		0	0	0	0
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	1	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		(2)	(1)	(32)	(1)
Interest expense, net		0	0	0	0
Provision for (benefit from) income taxes		0	0	0	0
Total assets		251	236	251	236
Capital expenditures		1	1	5	3
Rod and Refining Segment [Member] | Intersegment
Segment Reporting Information [Line Items]
Revenues		8	8	24	18
Atlantic Copper Smelting and Refining Segment [Member] | Operating Segments
Segment Reporting Information [Line Items]
Revenues		536	437	1,429	1,554
Cost of Goods Sold, Excluding Depreciation, Depletion, and Amortization (Deprecated 2019-01-31)		(522)	(421)	(1,379)	(1,488)
Cost, Depreciation, Amortization and Depletion		8	7	22	21
Metals inventory adjustments		0	0	0	0
Selling, general and administrative expenses		(5)	(5)	(15)	(15)
Mining exploration and research expenses		0	0	0	0
Environmental obligations and shutdown costs		0	0	0	0
Net gain on sales of assets		0	0	0	0
Operating income (loss)		4	4	29	35
Interest expense, net		0	5	4	17
Provision for (benefit from) income taxes		0	(1)	1	2
Total assets		877	680	877	680
Capital expenditures		6	9	17	18
Atlantic Copper Smelting and Refining Segment [Member] | Intersegment
Segment Reporting Information [Line Items]
Revenues		3	0	16	5
Corporate And Eliminations | Intersegment
Segment Reporting Information [Line Items]
Revenues		$ (1,343)	$ (1,223)	(3,554)	$ (3,654)
Forward Contracts [Member] | Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Matured derivative financial instruments				$ 24
Derivative, Nonmonetary Notional Amount, Mass | lb	150
Derivative, Average Forward Price | $ / lb	2.34