DERIVATIVES - FAIR VALUE (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Gross and net fair values of outstanding derivatives (in millions)
Collateral received netted against derivative assets	$ 45	$ 0
Collateral paid netted against derivative liabilities	1	54
Collateral deposited with clearinghouses and brokers	178	70
Cash-flow hedges \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset		0
Total net fair value, asset		3
Cash-flow hedges \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	0
Total net fair value, liability	2
Cash-flow hedges \| Level 1 \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross		0
Cash-flow hedges \| Level 1 \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Cash-flow hedges \| Level 2 \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross		3
Cash-flow hedges \| Level 2 \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	2
Cash-flow hedges \| Level 3 \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross		0
Cash-flow hedges \| Level 3 \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Not designated as hedging instruments \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	(2,392)	(517)
Total net fair value, asset	249	195
Not designated as hedging instruments \| Commodity contracts \| Long-term receivables and other assets, net
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	(6)	(1)
Total net fair value, asset	8	2
Not designated as hedging instruments \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	(2,392)	(517)
Total net fair value, liability	66	240
Not designated as hedging instruments \| Commodity contracts \| Deferred credits and liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	(6)	(1)
Total net fair value, liability	2	3
Not designated as hedging instruments \| Level 1 \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	2,531	485
Not designated as hedging instruments \| Level 1 \| Commodity contracts \| Long-term receivables and other assets, net
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	5	1
Not designated as hedging instruments \| Level 1 \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	2,357	535
Not designated as hedging instruments \| Level 1 \| Commodity contracts \| Deferred credits and liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	6	1
Not designated as hedging instruments \| Level 2 \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	110	227
Not designated as hedging instruments \| Level 2 \| Commodity contracts \| Long-term receivables and other assets, net
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	9	2
Not designated as hedging instruments \| Level 2 \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	101	222
Not designated as hedging instruments \| Level 2 \| Commodity contracts \| Deferred credits and liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	2	3
Not designated as hedging instruments \| Level 3 \| Commodity contracts \| Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0	0
Not designated as hedging instruments \| Level 3 \| Commodity contracts \| Long-term receivables and other assets, net
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0	0
Not designated as hedging instruments \| Level 3 \| Commodity contracts \| Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0	0
Not designated as hedging instruments \| Level 3 \| Commodity contracts \| Deferred credits and liabilities
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	$ 0	$ 0

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