Revenue - Disaggregation of revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of revenue
Revenue from customers	$ 6,102	$ 3,308	$ 11,286	$ 8,558
United States
Disaggregation of revenue
Revenue from customers	5,284	2,619	9,888	7,058
International
Disaggregation of revenue
Revenue from customers	1,049	851	1,895	1,861
Eliminations
Disaggregation of revenue
Revenue from customers	(231)	(162)	(497)	(361)
Oil and gas
Disaggregation of revenue
Revenue from customers	4,672	2,033	8,407	6,134
Oil and gas | Oil
Disaggregation of revenue
Revenue from customers	3,711	1,621	6,724	5,165
Oil and gas | NGL
Disaggregation of revenue
Revenue from customers	550	167	986	445
Oil and gas | Gas
Disaggregation of revenue
Revenue from customers	387	224	704	492
Oil and gas | Other
Disaggregation of revenue
Revenue from customers	24	21	(7)	32
Oil and gas | United States
Disaggregation of revenue
Revenue from customers	3,834	1,451	6,904	4,613
Oil and gas | United States | Oil
Disaggregation of revenue
Revenue from customers	3,028	1,166	5,492	3,921
Oil and gas | United States | NGL
Disaggregation of revenue
Revenue from customers	472	127	856	340
Oil and gas | United States | Gas
Disaggregation of revenue
Revenue from customers	311	138	564	321
Oil and gas | United States | Other
Disaggregation of revenue
Revenue from customers	23	20	(8)	31
Oil and gas | International
Disaggregation of revenue
Revenue from customers	838	582	1,503	1,521
Oil and gas | International | Oil
Disaggregation of revenue
Revenue from customers	683	455	1,232	1,244
Oil and gas | International | NGL
Disaggregation of revenue
Revenue from customers	78	40	130	105
Oil and gas | International | Gas
Disaggregation of revenue
Revenue from customers	76	86	140	171
Oil and gas | International | Other
Disaggregation of revenue
Revenue from customers	1	1	1	1
Oil and gas | Eliminations
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and gas | Eliminations | Oil
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and gas | Eliminations | NGL
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and gas | Eliminations | Gas
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and gas | Eliminations | Other
Disaggregation of revenue
Revenue from customers	0	0	0	0
Chemical
Disaggregation of revenue
Revenue from customers	1,187	839	2,274	1,800
Chemical | United States
Disaggregation of revenue
Revenue from customers	1,128	793	2,165	1,703
Chemical | International
Disaggregation of revenue
Revenue from customers	59	46	109	97
Chemical | Eliminations
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and marketing
Disaggregation of revenue
Revenue from customers	474	598	1,102	985
Midstream and marketing | United States
Disaggregation of revenue
Revenue from customers	322	375	819	742
Midstream and marketing | International
Disaggregation of revenue
Revenue from customers	152	223	283	243
Midstream and marketing | Eliminations
Disaggregation of revenue
Revenue from customers	$ 0	$ 0	$ 0	$ 0