Segment Disclosures and Related Information - Sales (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ 11,326	$ 4,386	$ 30,708	$ 13,293
Natural Gas [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	4,099	1,509	11,422	4,354
Natural Gas Liquids Reserves [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	414	129	976	364
Crude Oil [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	6,433	2,321	16,725	6,981
Other Products [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	380	427	1,585	1,594
U.S.
Segment Reporting Information [Line Items]
Sales and other operating revenues	8,963	3,148	23,978	9,209
Australia
Segment Reporting Information [Line Items]
Sales and other operating revenues	0	0	0	605
CA
Segment Reporting Information [Line Items]
Sales and other operating revenues	561	328	1,573	826
China
Segment Reporting Information [Line Items]
Sales and other operating revenues	193	161	519	374
Indonesia
Segment Reporting Information [Line Items]
Sales and other operating revenues	231	167	634	503
Libya
Segment Reporting Information [Line Items]
Sales and other operating revenues	313	6	833	50
Malaysia
Segment Reporting Information [Line Items]
Sales and other operating revenues	249	148	727	447
Norway
Segment Reporting Information [Line Items]
Sales and other operating revenues	678	358	1,708	1,046
United Kingdom
Segment Reporting Information [Line Items]
Sales and other operating revenues	136	68	729	224
Other foreign Countries
Segment Reporting Information [Line Items]
Sales and other operating revenues	2	2	7	9
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	11,326	4,386	30,708	13,293
Alaska [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,395	864	3,946	2,396
Alaska [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,395	834	3,946	2,385
Alaska [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	0	(30)	0	(11)
Lower 48 [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	7,566	2,323	19,968	6,859
Lower 48 [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	7,565	2,314	19,963	6,812
Lower 48 [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	(1)	(9)	(5)	(47)
Canada [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	967	348	2,636	1,026
Canada [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	561	328	1,573	826
Canada [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	(406)	(20)	(1,063)	(200)
Europe, Middle East and North Africa [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,127	432	3,270	1,320
Asia Pacific [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	673	477	1,880	1,930
Other International [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1	1	4	5
Corporate and Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ 4	$ 0	$ 72	$ 15