DERIVATIVES - FAIR VALUE (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Gross and net fair values of outstanding derivatives (in millions)
Collateral received netted against derivative assets	$ 4	$ 14
Collateral paid netted against derivative liabilities	13	4
Collateral deposited with clearinghouses and brokers	25	3
Cash-flow hedges | Commodity contracts | Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Total net fair value, asset	1	8
Cash-flow hedges | Commodity contracts | Other current assets | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	1	8
Cash-flow hedges | Commodity contracts | Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Total net fair value, liability	6	1
Cash-flow hedges | Commodity contracts | Accrued liabilities | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	6	1
Not designated as hedging instruments | Commodity contracts | Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Netting	(196)	(519)
Total net fair value, asset	27	107
Not designated as hedging instruments | Commodity contracts | Other current assets | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	166	554
Not designated as hedging instruments | Commodity contracts | Other current assets | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	57	72
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	(2)	(2)
Total net fair value, asset	3	7
Not designated as hedging instruments | Commodity contracts | Long-term receivables and other assets, net | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	2	3
Not designated as hedging instruments | Commodity contracts | Long-term receivables and other assets, net | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	3	6
Not designated as hedging instruments | Commodity contracts | Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	(196)	(519)
Total net fair value, liability	27	106
Not designated as hedging instruments | Commodity contracts | Accrued liabilities | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	172	541
Not designated as hedging instruments | Commodity contracts | Accrued liabilities | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	51	84
Not designated as hedging instruments | Commodity contracts | Deferred credits and other liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	(2)	(2)
Total net fair value, liability	5	6
Not designated as hedging instruments | Commodity contracts | Deferred credits and other liabilities | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	1	3
Not designated as hedging instruments | Commodity contracts | Deferred credits and other liabilities | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	$ 6	$ 5