Revenue - Disaggregation of revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of revenue
Revenue from customers	$ 5,184	$ 5,250
United States
Disaggregation of revenue
Revenue from customers	4,604	4,439
International
Disaggregation of revenue
Revenue from customers	846	1,010
Eliminations
Disaggregation of revenue
Revenue from customers	(266)	(199)
Oil and gas
Disaggregation of revenue
Revenue from customers	3,735	4,101
Oil and gas | Oil
Disaggregation of revenue
Revenue from customers	3,013	3,544
Oil and gas | NGL
Disaggregation of revenue
Revenue from customers	436	278
Oil and gas | Gas
Disaggregation of revenue
Revenue from customers	317	268
Oil and gas | Other
Disaggregation of revenue
Revenue from customers	(31)	11
Oil and gas | United States
Disaggregation of revenue
Revenue from customers	3,070	3,162
Oil and gas | United States | Oil
Disaggregation of revenue
Revenue from customers	2,464	2,755
Oil and gas | United States | NGL
Disaggregation of revenue
Revenue from customers	384	213
Oil and gas | United States | Gas
Disaggregation of revenue
Revenue from customers	253	183
Oil and gas | United States | Other
Disaggregation of revenue
Revenue from customers	(31)	11
Oil and gas | International
Disaggregation of revenue
Revenue from customers	665	939
Oil and gas | International | Oil
Disaggregation of revenue
Revenue from customers	549	789
Oil and gas | International | NGL
Disaggregation of revenue
Revenue from customers	52	65
Oil and gas | International | Gas
Disaggregation of revenue
Revenue from customers	64	85
Oil and gas | International | Other
Disaggregation of revenue
Revenue from customers	0	0
Oil and gas | Eliminations
Disaggregation of revenue
Revenue from customers	0	0
Oil and gas | Eliminations | Oil
Disaggregation of revenue
Revenue from customers	0	0
Oil and gas | Eliminations | NGL
Disaggregation of revenue
Revenue from customers	0	0
Oil and gas | Eliminations | Gas
Disaggregation of revenue
Revenue from customers	0	0
Oil and gas | Eliminations | Other
Disaggregation of revenue
Revenue from customers	0	0
Chemical
Disaggregation of revenue
Revenue from customers	1,087	961
Chemical | United States
Disaggregation of revenue
Revenue from customers	1,037	910
Chemical | International
Disaggregation of revenue
Revenue from customers	50	51
Chemical | Eliminations
Disaggregation of revenue
Revenue from customers	0	0
Midstream and marketing
Disaggregation of revenue
Revenue from customers	628	387
Midstream and marketing | Gas processing
Disaggregation of revenue
Revenue from customers	185	176
Midstream and marketing | Marketing
Disaggregation of revenue
Revenue from customers	485	195
Midstream and marketing | Power and other
Disaggregation of revenue
Revenue from customers	(42)	16
Midstream and marketing | United States
Disaggregation of revenue
Revenue from customers	497	367
Midstream and marketing | United States | Gas processing
Disaggregation of revenue
Revenue from customers	101	105
Midstream and marketing | United States | Marketing
Disaggregation of revenue
Revenue from customers	438	246
Midstream and marketing | United States | Power and other
Disaggregation of revenue
Revenue from customers	(42)	16
Midstream and marketing | International
Disaggregation of revenue
Revenue from customers	131	20
Midstream and marketing | International | Gas processing
Disaggregation of revenue
Revenue from customers	84	71
Midstream and marketing | International | Marketing
Disaggregation of revenue
Revenue from customers	47	(51)
Midstream and marketing | International | Power and other
Disaggregation of revenue
Revenue from customers	0	0
Midstream and marketing | Eliminations
Disaggregation of revenue
Revenue from customers	0	0
Midstream and marketing | Eliminations | Gas processing
Disaggregation of revenue
Revenue from customers	0	0
Midstream and marketing | Eliminations | Marketing
Disaggregation of revenue
Revenue from customers	0	0
Midstream and marketing | Eliminations | Power and other
Disaggregation of revenue
Revenue from customers	$ 0	$ 0