Revenue Recognition (Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 2,118	$ 2,943
E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	1,439	2,077
Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	679	866
Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	1,429	2,074
Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	2,041	2,755
Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1,352	1,886
Intersegment Revenues | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	(10)	(3)
Intersegment Revenues | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	1,362	1,889
Gas sales
Disaggregation of Revenue [Line Items]
Total operating revenues	1,145	1,692
Gas sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	1,136	1,690
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	(9)	(2)
Oil sales
Disaggregation of Revenue [Line Items]
Total operating revenues	95	111
Oil sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	94	110
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	201	272
NGL sales | Operating Segments | E&P
Disaggregation of Revenue [Line Items]
Total operating revenues	201	272
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	679	866
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	2,041	2,755
Marketing | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1,362	1,889
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)	2
Other | Operating Segments | Marketing
Disaggregation of Revenue [Line Items]
Total operating revenues	0	0
Other | Intersegment Revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	$ 0	$ 0