FAIR VALUE MEASUREMENT (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Other current assets	$ 270	$ 199
Other assets	2,270	1,956
Derivative Liability, Fair Value, Gross Liability	33	58
Derivatives:
Derivative Asset	166	132
Derivatives: [Abstract]
Derivative Liability	32	44
Level 1
Investment securities (current and long-term):
Available-for-sale Securities	5	27
Trust Assets Fair Value Disclosure	11	12
Derivatives:
Derivative Asset	9	8
Contingent receivable	0	0
Derivatives: [Abstract]
Derivative Liability	1	2
Discontinued Operation, Contingent Payable		0
Long-term debt, including current portion	0	0
Level 2
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Trust Assets Fair Value Disclosure	123	118
Derivatives:
Derivative Asset	266	184
Contingent receivable	0	0
Derivatives: [Abstract]
Derivative Liability	32	56
Discontinued Operation, Contingent Payable		23
Long-term debt, including current portion	13,269	15,196
Level 3
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Trust Assets Fair Value Disclosure	0	0
Derivatives:
Derivative Asset	0	0
Contingent receivable	134	135
Derivatives: [Abstract]
Derivative Liability	0	0
Discontinued Operation, Contingent Payable		0
Long-term debt, including current portion	0	0
Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Available-for-sale Securities	30	50
Trust Assets Fair Value Disclosure	189	183
Derivatives:
Derivative Asset	275	192
Contingent receivable	150	150
Derivatives: [Abstract]
Derivative Liability	33	58
Discontinued Operation, Contingent Payable		23
Long-term debt, including current portion	13,117	16,027
Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Available-for-sale Securities	30	50
Trust Assets Fair Value Disclosure	189	183
Derivatives:
Derivative Asset	275	192
Contingent receivable	134	135
Derivatives: [Abstract]
Derivative Liability	33	58
Discontinued Operation, Contingent Payable		23
Long-term debt, including current portion	13,269	15,196
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	31	56
Derivatives:
Derivative Asset	155	125
Derivatives: [Abstract]
Derivative Liability	31	44
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	155	137
Derivatives: [Abstract]
Derivative Liability	31	56
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	155	137
Derivatives: [Abstract]
Derivative Liability	31	56
Embedded Derivative Financial Instruments [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	155	137
Derivatives: [Abstract]
Derivative Liability	31	56
Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative Liability, Fair Value, Gross Liability	2	2
Derivatives:
Derivative Asset	11	7
Derivatives: [Abstract]
Derivative Liability	1	0
Commodity Contract [Member] | Level 1
Derivatives:
Derivative Asset		8
Derivatives: [Abstract]
Derivative Liability	1	2
Commodity Contract [Member] | Level 2
Derivatives:
Derivative Asset		1
Derivatives: [Abstract]
Derivative Liability	1	0
Commodity Contract [Member] | Level 3
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability	0	0
Commodity Contract [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset		9
Derivatives: [Abstract]
Derivative Liability	2	2
Commodity Contract [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset		9
Derivatives: [Abstract]
Derivative Liability	2	2
Future [Member] | Level 1
Derivatives:
Derivative Asset	9
Future [Member] | Level 2
Derivatives:
Derivative Asset	2
Future [Member] | Level 3
Derivatives:
Derivative Asset	0
Future [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset	11
Future [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	11
Forward Contracts [Member] | Level 1
Derivatives:
Derivative Asset	0
Forward Contracts [Member] | Level 2
Derivatives:
Derivative Asset	1
Forward Contracts [Member] | Level 3
Derivatives:
Derivative Asset	0
Forward Contracts [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset	1
Forward Contracts [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	1
Africa and onshore California [Member] | Commodity Contract [Member] | Level 1
Derivatives:
Derivative Asset	0
Africa and onshore California [Member] | Commodity Contract [Member] | Level 2
Derivatives:
Derivative Asset	108
Africa and onshore California [Member] | Commodity Contract [Member] | Level 3
Derivatives:
Derivative Asset	0
Africa and onshore California [Member] | Commodity Contract [Member] | Carrying Amount, Fair Value Disclosure [Member]
Derivatives:
Derivative Asset	108	46
Africa and onshore California [Member] | Commodity Contract [Member] | Estimate of Fair Value Measurement [Member]
Derivatives:
Derivative Asset	108	46
Africa and onshore California [Member] | Forward Contracts [Member] | Level 1
Derivatives:
Derivative Asset		0
Africa and onshore California [Member] | Forward Contracts [Member] | Level 2
Derivatives:
Derivative Asset		46
Africa and onshore California [Member] | Forward Contracts [Member] | Level 3
Derivatives:
Derivative Asset		0
U.S. core fixed income fund [Member] | Level 1
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund [Member] | Level 2
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund [Member] | Level 3
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Available-for-sale Securities	25	23
Trust Assets Fair Value Disclosure	55	53
U.S. core fixed income fund [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Available-for-sale Securities	25	23
Trust Assets Fair Value Disclosure	55	53
Money market funds [Member] | Level 1
Investment securities (current and long-term):
Available-for-sale Securities		22
Trust Assets Fair Value Disclosure	11	12
Money market funds [Member] | Level 2
Investment securities (current and long-term):
Available-for-sale Securities		0
Trust Assets Fair Value Disclosure	0	0
Money market funds [Member] | Level 3
Investment securities (current and long-term):
Available-for-sale Securities		0
Trust Assets Fair Value Disclosure	0	0
Money market funds [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Available-for-sale Securities		22
Trust Assets Fair Value Disclosure	11	12
Money market funds [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Available-for-sale Securities		22
Trust Assets Fair Value Disclosure	11	12
Equity securities | Level 1
Investment securities (current and long-term):
Available-for-sale Securities	5	5
Equity securities | Level 2
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Equity securities | Level 3
Investment securities (current and long-term):
Available-for-sale Securities	0	0
Equity securities | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Available-for-sale Securities	5	5
Equity securities | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Available-for-sale Securities	5	5
Government bonds | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government bonds | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	40	36
Government bonds | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government bonds | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	40	36
Government bonds | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	40	36
Government mortgage-backed securities [Member] | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities [Member] | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	27	25
Government mortgage-backed securities [Member] | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	27	25
Government mortgage-backed securities [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	27	25
Corporate bonds [Member] | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Corporate bonds [Member] | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	32	32
Corporate bonds [Member] | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Corporate bonds [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	32	32
Corporate bonds [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	32	32
Asset-backed securities [Member] | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities [Member] | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	15	16
Asset-backed securities [Member] | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	15	16
Asset-backed securities [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	15	16
Collateralized Mortgage Backed Securities [Member] | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities [Member] | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	8	8
Collateralized Mortgage Backed Securities [Member] | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	8	8
Collateralized Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	8	8
Municipal bonds [Member] | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Municipal bonds [Member] | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	1	1
Municipal bonds [Member] | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Municipal bonds [Member] | Carrying Amount, Fair Value Disclosure [Member]
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	1	1
Municipal bonds [Member] | Estimate of Fair Value Measurement [Member]
Investment securities (current and long-term):
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	52	28
Other assets	123	122
Investment Securities [Member]
Investment securities (current and long-term):
Alternative Investment, Fair Value Disclosure	25	23
Investment Securities [Member] | U.S. core fixed income fund [Member]
Investment securities (current and long-term):
Alternative Investment, Fair Value Disclosure	25	23
Restricted Funds [Member]
Investment securities (current and long-term):
Alternative Investment, Fair Value Disclosure	55	53
Restricted Funds [Member] | U.S. core fixed income fund [Member]
Investment securities (current and long-term):
Alternative Investment, Fair Value Disclosure	55	53
Derivatives Not Designated as Hedging Instruments [Member] | 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	31	56
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Estimate of Fair Value Measurement [Member]
Derivatives: [Abstract]
Long-term debt, including current portion	112	$ 98
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Derivatives Not Designated as Hedging Instruments [Member] | 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	$ 24