Operating Segments and Geographic Data - Segment Assets (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Segment Assets
Assets	$ 242,806	$ 239,790
Goodwill	4,402	4,402
United States
Segment Assets
Assets	72,208	69,938
International
Segment Assets
Assets	166,196	165,450
Operating Segments
Segment Assets
Assets	231,711	230,895
Operating Segments | Upstream
Segment Assets
Assets	188,317	191,309
Goodwill	4,402	4,402
Operating Segments | Upstream | United States
Segment Assets
Assets	41,713	42,431
Operating Segments | Upstream | International
Segment Assets
Assets	142,202	144,476
Operating Segments | Downstream
Segment Assets
Assets	43,394	39,586
Operating Segments | Downstream | United States
Segment Assets
Assets	25,659	23,490
Operating Segments | Downstream | International
Segment Assets
Assets	17,735	16,096
All Other
Segment Assets
Assets	11,095	8,895
All Other | United States
Segment Assets
Assets	4,836	4,017
All Other | International
Segment Assets
Assets	$ 6,259	$ 4,878