Revenue Recognition (Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 1,269	$ 4,138	$ 3,387	$ 7,081
E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	794	2,931	2,233	5,008
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	475	1,207	1,154	2,073
Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	777	2,929	2,206	5,003
Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,231	4,023	3,272	6,778
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	739	2,814	2,091	4,700
Intersegment Revenues | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	(17)	(2)	(27)	(5)
Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	756	2,816	2,118	4,705
Gas sales
Disaggregation of Revenue [Line Items]
Total operating revenues	551	2,485	1,696	4,177
Gas sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	535	2,485	1,671	4,175
Gas sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Gas sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	(16)	0	(25)	(2)
Oil sales
Disaggregation of Revenue [Line Items]
Total operating revenues	92	138	187	249
Oil sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	91	136	185	246
Oil sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Oil sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	(1)	(2)	(2)	(3)
NGL sales
Disaggregation of Revenue [Line Items]
Total operating revenues	153	310	354	582
NGL sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	153	310	354	582
NGL sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
NGL sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	475	1,207	1,154	2,073
Marketing | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0	0
Marketing | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,231	4,023	3,272	6,778
Marketing | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	756	2,816	2,118	4,705
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	(2)	(2)	(4)	$ 0
Other | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	(2)	(2)	(4)
Other | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0	0
Other | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 0	$ 0	$ 0