Inventory, Linefill and Base Gas and Long-term Inventory (Details) bbl in Thousands, Mcf in Thousands, $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($) $ / bbl $ / Mcf bbl Mcf	Dec. 31, 2019 USD ($) $ / bbl $ / Mcf Mcf bbl
Inventory by category
Inventory		$ 662	$ 604
Linefill and base gas		962	981
Long-term inventory		125	182
Total		1,749	$ 1,767
Charge related to the write-down of inventory	$ 232	$ 232
Charge related to the write-down of inventory, long-term inventory	$ 40
Crude oil
Inventory by category
Inventory, Volumes (in barrels or in Mcf) | bbl		20,306	8,613
Linefill and base gas, Volumes (in barrels or in Mcf) | bbl		14,491	14,316
Long-term inventory, Volumes (in barrels or in Mcf) | bbl		2,747	2,598
Inventory		$ 512	$ 450
Linefill and base gas		810	826
Long-term inventory		$ 104	$ 152
Inventory (Price/Unit of measure) | $ / bbl		25.21	52.25
Linefill and base gas (Price/Unit of measure) | $ / bbl		55.90	57.70
Long-term inventory (Price/Unit of measure) | $ / bbl		37.86	58.51
NGL
Inventory by category
Inventory, Volumes (in barrels or in Mcf) | bbl		10,923	7,574
Linefill and base gas, Volumes (in barrels or in Mcf) | bbl		1,645	1,701
Long-term inventory, Volumes (in barrels or in Mcf) | bbl		1,579	1,707
Inventory		$ 140	$ 142
Linefill and base gas		42	47
Long-term inventory		$ 21	$ 30
Inventory (Price/Unit of measure) | $ / bbl		12.82	18.75
Linefill and base gas (Price/Unit of measure) | $ / bbl		25.53	27.63
Long-term inventory (Price/Unit of measure) | $ / bbl		13.30	17.57
Natural gas
Inventory by category
Linefill and base gas, Volumes (in barrels or in Mcf) | Mcf		25,576	24,976
Linefill and base gas		$ 110	$ 108
Linefill and base gas (Price/Unit of measure) | $ / Mcf		4.30	4.32
Other
Inventory by category
Inventory		$ 10	$ 12