Revenue Recognition (Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 6,667	$ 2,308	$ 3,038
Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	4,701	1,391	1,740
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,966	917	1,298
Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	4,640	1,348	1,703
Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	6,189	2,145	2,850
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	(4,162)	(1,185)	(1,515)
Intersegment Revenues | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	61	43	37
Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	(4,223)	(1,228)	(1,552)
Gas sales
Disaggregation of Revenue [Line Items]
Total operating revenues	3,412	967	1,241
Gas sales | Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	3,358	928	1,207
Gas sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0
Gas sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	54	39	34
Oil sales
Disaggregation of Revenue [Line Items]
Total operating revenues	394	154	223
Oil sales | Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	389	150	220
Oil sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0
Oil sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	5	4	3
NGL sales
Disaggregation of Revenue [Line Items]
Total operating revenues	890	265	274
NGL sales | Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	888	265	274
NGL sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0
NGL sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	2	0	0
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,963	917	1,297
Marketing | Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0
Marketing | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	6,186	2,145	2,849
Marketing | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	(4,223)	(1,228)	(1,552)
Marketing | Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	(4,200)	(1,200)	(1,600)
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	8	5	3
Other | Operating Segments | Exploration and Production
Disaggregation of Revenue [Line Items]
Total operating revenues	5	5	2
Other | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	3	0	1
Other | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 0	$ 0	$ 0