DERIVATIVES - FAIR VALUE (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Gross and net fair values of outstanding derivatives (in millions)
Collateral paid netted against derivative liabilities	$ 104
Collateral deposited with clearinghouses and brokers	65	$ 54
Oil Collars and Calls | Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	0
Total net fair value, asset	92
Oil Collars and Calls | Other current assets | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0
Oil Collars and Calls | Other current assets | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	92
Oil Collars and Calls | Other current assets | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0
Oil Collars and Calls | Deferred credits and other liabilities - other
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	0
Total net fair value, liability	(160)
Oil Collars and Calls | Deferred credits and other liabilities - other | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Oil Collars and Calls | Deferred credits and other liabilities - other | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(160)
Oil Collars and Calls | Deferred credits and other liabilities - other | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Marketing Derivatives | Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	(973)	(2,392)
Total net fair value, asset	51	249
Marketing Derivatives | Other current assets | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	945	2,531
Marketing Derivatives | Other current assets | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	79	110
Marketing Derivatives | Other current assets | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0	0
Marketing Derivatives | Long-term receivables and other assets, net
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	(4)	(6)
Total net fair value, asset	12	8
Marketing Derivatives | Long-term receivables and other assets, net | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	4	5
Marketing Derivatives | Long-term receivables and other assets, net | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	12	9
Marketing Derivatives | Long-term receivables and other assets, net | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0	0
Marketing Derivatives | Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	973	2,392
Total net fair value, liability	(79)	(66)
Marketing Derivatives | Accrued liabilities | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(1,008)	(2,357)
Marketing Derivatives | Accrued liabilities | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(44)	(101)
Marketing Derivatives | Accrued liabilities | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0	0
Marketing Derivatives | Deferred credits and other liabilities - other
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	4	6
Total net fair value, liability	(1)	(2)
Marketing Derivatives | Deferred credits and other liabilities - other | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(4)	(6)
Marketing Derivatives | Deferred credits and other liabilities - other | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(1)	(2)
Marketing Derivatives | Deferred credits and other liabilities - other | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0	$ 0
Interest Rate Swaps | Other current assets
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	0
Total net fair value, asset	5
Interest Rate Swaps | Other current assets | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0
Interest Rate Swaps | Other current assets | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	5
Interest Rate Swaps | Other current assets | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0
Interest Rate Swaps | Long-term receivables and other assets, net
Gross and net fair values of outstanding derivatives (in millions)
Netting, asset	0
Total net fair value, asset	5
Interest Rate Swaps | Long-term receivables and other assets, net | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0
Interest Rate Swaps | Long-term receivables and other assets, net | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	5
Interest Rate Swaps | Long-term receivables and other assets, net | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative asset, gross	0
Interest Rate Swaps | Accrued liabilities
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	0
Total net fair value, liability	(657)
Interest Rate Swaps | Accrued liabilities | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Interest Rate Swaps | Accrued liabilities | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(657)
Interest Rate Swaps | Accrued liabilities | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Interest Rate Swaps | Deferred credits and other liabilities - other
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	0
Total net fair value, liability	(776)
Interest Rate Swaps | Deferred credits and other liabilities - other | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Interest Rate Swaps | Deferred credits and other liabilities - other | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(776)
Interest Rate Swaps | Deferred credits and other liabilities - other | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Warrant | Deferred credits and other liabilities - other
Gross and net fair values of outstanding derivatives (in millions)
Netting and collateral, liability	0
Total net fair value, liability	(107)
Warrant | Deferred credits and other liabilities - other | Level 1
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	0
Warrant | Deferred credits and other liabilities - other | Level 2
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	(107)
Warrant | Deferred credits and other liabilities - other | Level 3
Gross and net fair values of outstanding derivatives (in millions)
Commodity contract derivative liability, gross	$ 0