DERIVATIVES (Outstanding Derivative Balances) (Details) - Commodity Risk - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	$ 8	$ 20
Derivative Asset, Netting	0	0
Cash Collateral	37	31
Total Derivative Balance, Assets	45	51
Current assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	30	30
Derivative Asset, Netting	(2)	(3)
Cash Collateral	6	10
Total Derivative Balance, Assets	34	37
Other noncurrent assets – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Assets	98	103
Derivative Asset, Netting	(1)	(1)
Cash Collateral	0	0
Total Derivative Balance, Assets	97	102
Current liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Liabilities	(52)	(47)
Derivative Liability, Netting	2	3
Cash Collateral	19	13
Total Derivative Balance, Liabilities	(31)	(31)
Noncurrent liabilities – other
Derivatives And Hedging Activities [Line Items]
Gross Derivative Liabilities	(68)	(66)
Derivative Liability, Netting	1	1
Cash Collateral	12	8
Total Derivative Balance, Liabilities	$ (55)	$ (57)