Revenue Recognition (Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 2,943	$ 1,072
E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	2,077	719
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	866	353
Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	2,074	705
Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	2,755	997
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1,886	630
Intersegment Revenues | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	(3)	(14)
Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,889	644
Gas sales
Disaggregation of Revenue [Line Items]
Total operating revenues	1,692	464
Gas sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	1,690	451
Gas sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0
Gas sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	2	13
Oil sales
Disaggregation of Revenue [Line Items]
Total operating revenues	111	81
Oil sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	110	80
Oil sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0
Oil sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1	1
NGL sales
Disaggregation of Revenue [Line Items]
Total operating revenues	272	173
NGL sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	272	173
NGL sales | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0
NGL sales | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	866	352
Marketing | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0
Marketing | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	2,755	996
Marketing | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1,889	644
Other
Disaggregation of Revenue [Line Items]
Total operating revenues	2	2
Other | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	2	1
Other | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	1
Other | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 0	$ 0