Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Included in operating activities:
Interest paid, net of amounts capitalized	$ 126	$ 128
Income taxes paid to taxing authorities, net of refunds received	4	66
Noncash investing activities:
Increase (decrease) in asset retirement costs	(6)	29
Asset retirement obligations assumed by buyer	0	109
Proceeds from income tax refunds	4	89
Capital expenditures incurred but not yet paid	$ 48	300
Droshky Field
Noncash investing activities:
Asset retirement obligations assumed by buyer		$ 98