Revenue Recognition (Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 1,443	$ 4,541	$ 4,830	$ 11,622
E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	890	3,243	3,123	8,251
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	553	1,298	1,707	3,371
Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	873	3,247	3,079	8,250
Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,379	4,436	4,651	11,214
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	809	3,142	2,900	7,842
Intersegment Revenues | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	(17)	4	(44)	(1)
Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	826	3,138	2,944	7,843
Gas sales
Disaggregation of Revenue [Line Items]
Total operating revenues	627	2,884	2,323	7,061
Gas sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	610	2,889	2,281	7,064
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	(17)	5	(42)	3
Oil sales
Disaggregation of Revenue [Line Items]
Total operating revenues	94	100	281	349
Oil sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	93	99	278	345
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)	(1)	(3)	(4)
NGL sales
Disaggregation of Revenue [Line Items]
Total operating revenues	169	260	523	842
NGL sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	170	260	524	842
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	1	0	1	0
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	553	1,298	1,707	3,371
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	1,379	4,436	4,651	11,214
Marketing | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	826	3,138	2,944	7,843
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 0	(1)	(4)	(1)
Other | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues		(1)	(4)	(1)
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