FAIR VALUE MEASUREMENT (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Other current assets	$ 422	$ 286
Other assets	2,172	2,273
Derivative Liability, Fair Value, Gross Liability	48	57
Derivatives:
Derivative Asset	16	166
Derivatives: [Abstract]
Derivative Liability	41	56
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	25	25
Assets [Abstract]
Trust Assets Fair Value Disclosure	55	55
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	4	5
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	11
Derivatives:
Derivative Asset	0	9
Contingent receivable	0	0
Derivatives: [Abstract]
Derivative Liability	7	1
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	121	123
Derivatives:
Derivative Asset	96	266
Contingent receivable	0	0
Derivatives: [Abstract]
Derivative Liability	41	56
Long-term debt, including current portion	10,238	13,381
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	127	134
Derivatives: [Abstract]
Derivative Liability	0	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	29	30
Assets [Abstract]
Trust Assets Fair Value Disclosure	181	189
Derivatives:
Derivative Asset	96	275
Contingent receivable	143	150
Derivatives: [Abstract]
Derivative Liability	48	57
Long-term debt, including current portion	11,141	13,229
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	29	30
Assets [Abstract]
Trust Assets Fair Value Disclosure	181	189
Derivatives:
Derivative Asset	96	275
Contingent receivable	127	134
Derivatives: [Abstract]
Derivative Liability	48	57
Long-term debt, including current portion	10,238	13,381
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	39	55
Derivatives:
Derivative Asset	16	155
Derivatives: [Abstract]
Derivative Liability	32	55
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	23	155
Derivatives: [Abstract]
Derivative Liability	39	55
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	23	155
Derivatives: [Abstract]
Derivative Liability	39	55
Embedded Derivative Financial Instruments [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	23	155
Derivatives: [Abstract]
Derivative Liability	39	55
Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative Liability, Fair Value, Gross Liability	9	2
Derivatives:
Derivative Asset	0	11
Derivatives: [Abstract]
Derivative Liability	9	1
Commodity Contract [Member] | Level 1
Derivatives:
Derivative Asset		9
Derivatives: [Abstract]
Derivative Liability	7
Commodity Contract [Member] | Level 2
Derivatives:
Derivative Asset		2
Derivatives: [Abstract]
Derivative Liability	2
Commodity Contract [Member] | Level 3
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability	0
Commodity Contract [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset		11
Derivatives: [Abstract]
Derivative Liability	9
Commodity Contract [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset		11
Derivatives: [Abstract]
Derivative Liability	9
Forward Contracts [Member] | Level 1
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability		1
Forward Contracts [Member] | Level 2
Derivatives:
Derivative Asset		1
Derivatives: [Abstract]
Derivative Liability		1
Forward Contracts [Member] | Level 3
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability		0
Forward Contracts [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset		1
Derivatives: [Abstract]
Derivative Liability		2
Forward Contracts [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset		1
Derivatives: [Abstract]
Derivative Liability		2
Africa and onshore California [Member] | Commodity Contract [Member] | Level 1
Derivatives:
Derivative Asset	0	0
Africa and onshore California [Member] | Commodity Contract [Member] | Level 2
Derivatives:
Derivative Asset	73	108
Africa and onshore California [Member] | Commodity Contract [Member] | Level 3
Derivatives:
Derivative Asset	0	0
Africa and onshore California [Member] | Commodity Contract [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset	73	108
Africa and onshore California [Member] | Commodity Contract [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	73	108
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	25	25
Assets [Abstract]
Trust Assets Fair Value Disclosure	55	55
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	25	25
Assets [Abstract]
Trust Assets Fair Value Disclosure	55	55
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	25	25
Assets [Abstract]
Trust Assets Fair Value Disclosure	55	55
Money market funds [Member] | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	11
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	11
Money market funds [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	5	11
Equity securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	4	5
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	4	5
Equity securities | Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Marketable Securities	4	5
Government bonds | Level 1
Assets [Abstract]
Trust Assets Fair Value Disclosure	0	0
Government bonds | Level 2
Assets [Abstract]
Trust Assets Fair Value Disclosure	36	40
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	36	40
Government bonds | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	36	40
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	38	27
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	38	27
Government mortgage-backed securities [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	38	27
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	28	32
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	28	32
Corporate bonds [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	28	32
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	11	15
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	11	15
Asset-backed securities [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	11	15
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	7	8
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	7	8
Collateralized Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member]
Assets [Abstract]
Trust Assets Fair Value Disclosure	7	8
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	109	52
Other assets	126	123
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	$ 39	$ 55