Operating Segments and Geographic Data (Details 4) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ 34,189	$ 35,968
Oil and Gas
Segment Reporting Information [Line Items]
Sales and other operating revenues	34,189	35,968
Oil and Gas | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	42,370	42,440
Oil and Gas | All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	224	230
Oil and Gas | Total All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	66	61
Oil and Gas | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	18,492	17,846
Oil and Gas | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(156)	(166)
Oil and Gas | United States | All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	222	227
Oil and Gas | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(4,622)	(2,926)
Oil and Gas | International | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	23,878	24,594
Oil and Gas | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(2)	(3)
Oil and Gas | International | All Other
Segment Reporting Information [Line Items]
Sales and other operating revenues	2	3
Oil and Gas | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(3,559)	(3,546)
Oil and Gas | Upstream
Segment Reporting Information [Line Items]
Sales and other operating revenues	8,440	7,261
Oil and Gas | Upstream | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	15,251	13,233
Oil and Gas | Upstream | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	5,882	4,577
Oil and Gas | Upstream | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(3,519)	(2,757)
Oil and Gas | Upstream | International | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	9,369	8,656
Oil and Gas | Upstream | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(3,292)	(3,215)
Oil and Gas | Downstream
Segment Reporting Information [Line Items]
Sales and other operating revenues	25,683	28,646
Oil and Gas | Downstream | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	26,895	28,977
Oil and Gas | Downstream | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	12,388	13,042
Oil and Gas | Downstream | United States | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	(947)	(3)
Oil and Gas | Downstream | International | Operating Segments
Segment Reporting Information [Line Items]
Sales and other operating revenues	14,507	15,935
Oil and Gas | Downstream | International | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales and other operating revenues	$ (265)	$ (328)