FAIR VALUE MEASUREMENT (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / bbl	Dec. 31, 2019 USD ($) $ / bbl	Dec. 31, 2018 USD ($) $ / bbl	Dec. 31, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Other current assets	$ 341	$ 655
Other assets	1,560	1,885
Derivative Liability, Fair Value, Gross Liability	21	21
Derivatives:
Derivative Asset	183	74
Derivatives: [Abstract]
Derivative Liability	20	21
Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	29	27
Assets [Abstract]
Trust Assets Fair Value Disclosure	65	59
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	7	4
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	3
Derivatives:
Derivative Asset	13	5
Contingent receivable	0	0
Derivatives: [Abstract]
Derivative Liability		0
Long-term debt, including current portion	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	0	0
Assets [Abstract]
Trust Assets Fair Value Disclosure	143	134
Derivatives:
Derivative Asset	171	80
Contingent receivable	0	0
Derivatives: [Abstract]
Derivative Liability		21
Long-term debt, including current portion	10,994	10,239
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	0	0
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Derivatives:
Derivative Asset	0	0
Contingent receivable	88	108
Derivatives: [Abstract]
Derivative Liability		0
Long-term debt, including current portion	0	0
Carrying Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	36	31
Assets [Abstract]
Trust Assets Fair Value Disclosure	213	196
Derivatives:
Derivative Asset	184	85
Contingent receivable	108	122
Derivatives: [Abstract]
Derivative Liability		21
Long-term debt, including current portion	9,711	9,826
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	36	31
Assets [Abstract]
Trust Assets Fair Value Disclosure	213	196
Derivatives:
Derivative Asset	184	85
Contingent receivable	88	108
Derivatives: [Abstract]
Derivative Liability		21
Long-term debt, including current portion	10,994	10,239
Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative Liability, Fair Value, Gross Liability	21	20
Derivatives:
Derivative Asset	168	68
Derivatives: [Abstract]
Derivative Liability	20	20
Embedded Derivative Financial Instruments [Member] | Level 1
Derivatives:
Derivative Asset	0	0
Derivatives: [Abstract]
Derivative Liability	0	0
Embedded Derivative Financial Instruments [Member] | Level 2
Derivatives:
Derivative Asset	169	68
Derivatives: [Abstract]
Derivative Liability	21	20
Embedded Derivative Financial Instruments [Member] | Level 3
Derivatives:
Derivative Asset	0	0
Derivatives: [Abstract]
Derivative Liability	0	0
Embedded Derivative Financial Instruments [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset	169	68
Derivatives: [Abstract]
Derivative Liability	21	20
Embedded Derivative Financial Instruments [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	169	68
Derivatives: [Abstract]
Derivative Liability	21	20
Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	1
Derivatives:
Derivative Asset	15	6
Derivatives: [Abstract]
Derivative Liability	0	1
Commodity Contract [Member] | Level 1
Derivatives: [Abstract]
Derivative Liability		0
Commodity Contract [Member] | Level 2
Derivatives: [Abstract]
Derivative Liability		1
Commodity Contract [Member] | Level 3
Derivatives: [Abstract]
Derivative Liability		0
Commodity Contract [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives: [Abstract]
Derivative Liability		1
Commodity Contract [Member] | Estimate of Fair Value Measurement [Member]
Derivatives: [Abstract]
Derivative Liability		1
Future [Member] | Level 1
Derivatives:
Derivative Asset	13	5
Future [Member] | Level 2
Derivatives:
Derivative Asset	2	1
Future [Member] | Level 3
Derivatives:
Derivative Asset	0
Future [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset	15	6
Future [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	15	6
Onshore California | Commodity Contract [Member] | Level 1
Derivatives:
Derivative Asset		0
Onshore California | Commodity Contract [Member] | Level 2
Derivatives:
Derivative Asset		11
Onshore California | Commodity Contract [Member] | Level 3
Derivatives:
Derivative Asset		0
Onshore California | Commodity Contract [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset		11
Onshore California | Commodity Contract [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset		11
U.S. core fixed income fund [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	29	27
Assets [Abstract]
Trust Assets Fair Value Disclosure	65	59
U.S. core fixed income fund [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	0	0
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	0	0
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	0	0
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund [Member] | Carrying Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	29	27
Assets [Abstract]
Trust Assets Fair Value Disclosure	65	59
U.S. core fixed income fund [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	29	27
Assets [Abstract]
Trust Assets Fair Value Disclosure	65	59
Money market funds [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	3
Money market funds [Member] | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Money market funds [Member] | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Money market funds [Member] | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	3
Money market funds [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	3
Equity securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	7	4
Equity securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	0	0
Equity securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	0	0
Equity securities | Carrying Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	7	4
Equity securities | Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	7	4
Government bonds | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Government bonds | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	49	36
Government bonds | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Government bonds | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	49	36
Government bonds | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	49	36
Government mortgage-backed securities [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities [Member] | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	30	43
Government mortgage-backed securities [Member] | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities [Member] | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	30	43
Government mortgage-backed securities [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	30	43
Corporate bonds [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Corporate bonds [Member] | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	43	33
Corporate bonds [Member] | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Corporate bonds [Member] | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	43	33
Corporate bonds [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	43	33
Asset-backed securities [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities [Member] | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	16	14
Asset-backed securities [Member] | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities [Member] | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	16	14
Asset-backed securities [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	16	14
Collateralized Mortgage Backed Securities [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities [Member] | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	4	7
Collateralized Mortgage Backed Securities [Member] | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities [Member] | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	4	7
Collateralized Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	4	7
Municipal bonds [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Municipal bonds [Member] | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	1	1
Municipal bonds [Member] | Level 3
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Municipal bonds [Member] | Carrying Amount, Fair Value Disclosure [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	1	1
Municipal bonds [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	1	1
Bank Time Deposits [Member] | Carrying Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Other current assets	97	100
Other assets	148	157
Derivatives Not Designated as Hedging Instruments | Embedded Derivative Financial Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative Liability, Fair Value, Gross Liability	21	20
Freeport-McMoRan Oil & Gas | Onshore California
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Other assets		11
Other assets			$ 50
Derivatives:
Contingent receivable	50			$ 150
Derivatives: [Abstract]
Contingent consideration asset, per year	50	50	$ 50
Freeport-McMoRan Oil & Gas | Deepwater Gulf of Mexico Interests
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Other current assets	12	18
Other assets	$ 96	$ 104
Derivatives:
Contingent receivable				$ 150
Crude Oil | Freeport-McMoRan Oil & Gas | Onshore California
Derivatives: [Abstract]
Contingent consideration, reference threshold, price per barrel (in us dollars per pound) | $ / bbl	70	70	70