DERIVATIVES (Outstanding Derivative Balances) (Details) - Commodity Risk - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	$ 16	$ 20
Derivative Asset, Netting	0	0
Cash Collateral	21	31
Total Derivative Balance, Assets	37	51
Current assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	34	30
Derivative Asset, Netting	(2)	(3)
Cash Collateral	5	10
Total Derivative Balance, Assets	37	37
Other noncurrent assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	88	103
Derivative Asset, Netting	0	(1)
Cash Collateral	0	0
Total Derivative Balance, Assets	88	102
Current liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Liabilities	(39)	(47)
Derivative Liability, Netting	2	3
Cash Collateral	12	13
Total Derivative Balance, Liabilities	(25)	(31)
Noncurrent liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Liabilities	(67)	(66)
Derivative Liability, Netting	0	1
Cash Collateral	4	8
Total Derivative Balance, Liabilities	$ (63)	$ (57)