Sales and Other Operating Revenues - Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from contracts with customers	$ 11,326	$ 4,386	$ 30,708	$ 13,293
Customers within the scope of ASC Topic 606 [Member]
Revenue from contracts with customers	8,880	3,078	23,794	9,908
Physical gas contracts [Member]
Revenue from contracts with customers	2,620	1,280	7,348	3,432
Crude oil product line [Member]
Revenue from contracts with customers	215	100	517	218
Natural Gas Product Line [Member]
Revenue from contracts with customers	2,192	1,042	6,423	2,895
Other Products [Member]
Revenue from contracts with customers	213	138	408	319
Financial Derivative Contracts [Member]
Revenue from contracts with customers	(174)	28	(434)	(47)
Lower 48 Segment \| Physical gas contracts [Member]
Revenue from contracts with customers	2,123	1,018	5,934	2,692
Canada Segment [Member] \| Physical gas contracts [Member]
Revenue from contracts with customers	266	152	776	452
Europe, Middle East and North Africa [Member] \| Physical gas contracts [Member]
Revenue from contracts with customers	$ 231	$ 110	$ 638	$ 288