DERIVATIVES (Outstanding Derivative Balances) (Details) - Commodity Risk - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	$ 13	$ 20
Derivative Asset, Netting	0	0
Cash Collateral	28	31
Total Derivative Balance, Assets	41	51
Current assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	30	30
Derivative Asset, Netting	(2)	(3)
Cash Collateral	4	10
Total Derivative Balance, Assets	32	37
Other noncurrent assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	89	103
Derivative Asset, Netting	0	(1)
Cash Collateral	0	0
Total Derivative Balance, Assets	89	102
Current liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Liabilities	(42)	(47)
Derivative Liability, Netting	2	3
Cash Collateral	16	13
Total Derivative Balance, Liabilities	(24)	(31)
Noncurrent liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Liabilities	(64)	(66)
Derivative Liability, Netting	0	1
Cash Collateral	8	8
Total Derivative Balance, Liabilities	$ (56)	$ (57)