Operating Segments and Geographic Data - Segment Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ 15,926	$ 36,323	$ 45,631	$ 70,512
Oil and Gas
Segment Reporting Information [Line Items]
Sales and other operating revenues	15,926	36,323	45,631	70,512
Oil and Gas | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	19,085	44,736	56,135	87,106
Oil and Gas | All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	233	276	445	500
Oil and Gas | Total All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	33	60	98	126
Oil and Gas | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	8,006	21,053	23,868	39,545
Oil and Gas | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(194)	(211)	(339)	(367)
Oil and Gas | United States | All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	227	271	437	493
Oil and Gas | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(1,946)	(5,118)	(6,163)	(9,740)
Oil and Gas | International | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	11,079	23,683	32,267	47,561
Oil and Gas | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(6)	(5)	(8)	(7)
Oil and Gas | International | All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	6	5	8	7
Oil and Gas | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(1,213)	(3,295)	(4,341)	(6,854)
Oil and Gas | Upstream
Segment Reporting Information [Line Items]
Sales and other operating revenues	4,657	7,935	12,783	16,375
Oil and Gas | Upstream | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	7,098	14,904	20,577	30,155
Oil and Gas | Upstream | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	2,544	5,927	7,010	11,809
Oil and Gas | Upstream | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(1,420)	(3,865)	(4,232)	(7,384)
Oil and Gas | Upstream | International | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	4,554	8,977	13,567	18,346
Oil and Gas | Upstream | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(1,021)	(3,104)	(3,562)	(6,396)
Oil and Gas | Downstream
Segment Reporting Information [Line Items]
Sales and other operating revenues	11,236	28,328	32,750	54,011
Oil and Gas | Downstream | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	11,754	29,556	35,113	56,451
Oil and Gas | Downstream | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	5,235	14,855	16,421	27,243
Oil and Gas | Downstream | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(332)	(1,042)	(1,592)	(1,989)
Oil and Gas | Downstream | International | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	6,519	14,701	18,692	29,208
Oil and Gas | Downstream | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ (186)	$ (186)	$ (771)	$ (451)