DERIVATIVES - Commodity Price Risk (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) bbl / d $ / bbl	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Derivatives
Non-cash derivative (losses) gains | $	$ (170)	$ 229	$ (83)
Net proceeds (payments) on settled commodity derivatives | $	$ 111	$ (228)	$ (7)
Puts | Purchased | Q1 2020
Derivatives
Daily volume (in Bbl) | bbl / d	30,000
Weighted-average price (in dollars per barrel) | $ / bbl	70.83
Puts | Purchased | Q2 2020
Derivatives
Daily volume (in Bbl) | bbl / d	20,000
Weighted-average price (in dollars per barrel) | $ / bbl	67.50
Puts | Purchased | Q3 2020
Derivatives
Daily volume (in Bbl) | bbl / d	13,000
Weighted-average price (in dollars per barrel) | $ / bbl	65.00
Puts | Purchased | Q4 2020
Derivatives
Daily volume (in Bbl) | bbl / d	8,000
Weighted-average price (in dollars per barrel) | $ / bbl	65.00
Puts | Sold | Q1 2020
Derivatives
Daily volume (in Bbl) | bbl / d	30,000
Weighted-average price (in dollars per barrel) | $ / bbl	56.67
Puts | Sold | Q2 2020
Derivatives
Daily volume (in Bbl) | bbl / d	20,000
Weighted-average price (in dollars per barrel) | $ / bbl	53.75
Puts | Sold | Q3 2020
Derivatives
Daily volume (in Bbl) | bbl / d	18,000
Weighted-average price (in dollars per barrel) | $ / bbl	54.31
Puts | Sold | Q4 2020
Derivatives
Daily volume (in Bbl) | bbl / d	13,000
Weighted-average price (in dollars per barrel) | $ / bbl	53.81
Swaps | Q1 2020
Derivatives
Daily volume (in Bbl) | bbl / d	0
Weighted-average price (in dollars per barrel) | $ / bbl	0
Swaps | Q2 2020
Derivatives
Daily volume (in Bbl) | bbl / d	5,000
Weighted-average price (in dollars per barrel) | $ / bbl	70.05
Swaps | Q3 2020
Derivatives
Daily volume (in Bbl) | bbl / d	5,000
Weighted-average price (in dollars per barrel) | $ / bbl	65.00
Swaps | Q4 2020
Derivatives
Daily volume (in Bbl) | bbl / d	5,000
Weighted-average price (in dollars per barrel) | $ / bbl	65.00
Swaps | Second Half of 2020
Derivatives
Daily volume (in Bbl) | bbl / d	5,000
Weighted-average price (in dollars per barrel) | $ / bbl	65.00
Crude Oil | BSP JV | Puts | Purchased | Year2019 Through2021
Derivatives
Daily volume (in Bbl) | bbl / d	2,000
Weighted-average price (in dollars per barrel) | $ / bbl	50.00
Crude Oil | BSP JV | Puts | Purchased | Year 2021
Derivatives
Daily volume (in Bbl) | bbl / d	1,000
Weighted-average price (in dollars per barrel) | $ / bbl	45.00
Crude Oil | BSP JV | Calls | Sold | 2019 Through 2020
Derivatives
Daily volume (in Bbl) | bbl / d	500
Weighted-average price (in dollars per barrel) | $ / bbl	60.00