Revenue - Disaggregation of revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of revenue
Revenue from customers	$ 4,018	$ 5,403	$ 12,576	$ 12,569
United States
Disaggregation of revenue
Revenue from customers	3,346	4,420	10,404	9,480
Middle East / Africa
Disaggregation of revenue
Revenue from customers	600	1,080	2,039	3,137
Latin America
Disaggregation of revenue
Revenue from customers	174	218	466	657
Other International
Disaggregation of revenue
Revenue from customers	80	53	210	90
Eliminations
Disaggregation of revenue
Revenue from customers	(182)	(368)	(543)	(795)
Eliminations | United States
Disaggregation of revenue
Revenue from customers	0	0	0	0
Eliminations | Middle East / Africa
Disaggregation of revenue
Revenue from customers	0	0	0	0
Eliminations | Latin America
Disaggregation of revenue
Revenue from customers	0	0	0	0
Eliminations | Other International
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas
Disaggregation of revenue
Revenue from customers	2,882	3,918	9,016	8,987
Oil and Gas | Oil
Disaggregation of revenue
Revenue from customers	2,319	3,482	7,484	8,064
Oil and Gas | NGL
Disaggregation of revenue
Revenue from customers	305	243	750	538
Oil and Gas | Gas
Disaggregation of revenue
Revenue from customers	235	208	727	427
Oil and Gas | Other
Disaggregation of revenue
Revenue from customers	23	(15)	55	(42)
Oil and Gas | United States
Disaggregation of revenue
Revenue from customers	2,214	2,737	6,827	5,584
Oil and Gas | United States | Oil
Disaggregation of revenue
Revenue from customers	1,784	2,453	5,705	5,105
Oil and Gas | United States | NGL
Disaggregation of revenue
Revenue from customers	252	177	592	339
Oil and Gas | United States | Gas
Disaggregation of revenue
Revenue from customers	155	125	476	180
Oil and Gas | United States | Other
Disaggregation of revenue
Revenue from customers	23	(18)	54	(40)
Oil and Gas | Middle East / Africa
Disaggregation of revenue
Revenue from customers	527	999	1,824	2,865
Oil and Gas | Middle East / Africa | Oil
Disaggregation of revenue
Revenue from customers	397	852	1,426	2,435
Oil and Gas | Middle East / Africa | NGL
Disaggregation of revenue
Revenue from customers	53	66	158	199
Oil and Gas | Middle East / Africa | Gas
Disaggregation of revenue
Revenue from customers	77	78	239	233
Oil and Gas | Middle East / Africa | Other
Disaggregation of revenue
Revenue from customers	0	3	1	(2)
Oil and Gas | Latin America
Disaggregation of revenue
Revenue from customers	141	182	365	538
Oil and Gas | Latin America | Oil
Disaggregation of revenue
Revenue from customers	138	177	353	524
Oil and Gas | Latin America | NGL
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas | Latin America | Gas
Disaggregation of revenue
Revenue from customers	3	5	12	14
Oil and Gas | Latin America | Other
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas | Other International
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas | Other International | Oil
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas | Other International | NGL
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas | Other International | Gas
Disaggregation of revenue
Revenue from customers	0	0	0	0
Oil and Gas | Other International | Other
Disaggregation of revenue
Revenue from customers	0	0	0	0
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	939	1,061	2,739	3,109
Chemical | United States
Disaggregation of revenue
Revenue from customers	888	1,009	2,591	2,937
Chemical | Middle East / Africa
Disaggregation of revenue
Revenue from customers	0	0	0	0
Chemical | Latin America
Disaggregation of revenue
Revenue from customers	33	36	101	119
Chemical | Other International
Disaggregation of revenue
Revenue from customers	18	16	47	53
Chemical | Eliminations
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing
Disaggregation of revenue
Revenue from customers	379	409	1,364	885
Midstream and Marketing | Gas Processing
Disaggregation of revenue
Revenue from customers	162	174	476	574
Midstream and Marketing | Marketing
Disaggregation of revenue
Revenue from customers	172	194	818	199
Midstream and Marketing | Power and Other
Disaggregation of revenue
Revenue from customers	45	41	70	112
Midstream and Marketing | United States
Disaggregation of revenue
Revenue from customers	244	291	986	576
Midstream and Marketing | United States | Gas Processing
Disaggregation of revenue
Revenue from customers	89	93	261	302
Midstream and Marketing | United States | Marketing
Disaggregation of revenue
Revenue from customers	110	157	655	162
Midstream and Marketing | United States | Power and Other
Disaggregation of revenue
Revenue from customers	45	41	70	112
Midstream and Marketing | Middle East / Africa
Disaggregation of revenue
Revenue from customers	73	81	215	272
Midstream and Marketing | Middle East / Africa | Gas Processing
Disaggregation of revenue
Revenue from customers	73	81	215	272
Midstream and Marketing | Middle East / Africa | Marketing
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Middle East / Africa | Power and Other
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Latin America
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Latin America | Gas Processing
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Latin America | Marketing
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Latin America | Power and Other
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Other International
Disaggregation of revenue
Revenue from customers	62	37	163	37
Midstream and Marketing | Other International | Gas Processing
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Other International | Marketing
Disaggregation of revenue
Revenue from customers	62	37	163	37
Midstream and Marketing | Other International | Power and Other
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Eliminations
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Eliminations | Gas Processing
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Eliminations | Marketing
Disaggregation of revenue
Revenue from customers	0	0	0	0
Midstream and Marketing | Eliminations | Power and Other
Disaggregation of revenue
Revenue from customers	$ 0	0	$ 0	0
WES Midstream
Disaggregation of revenue
Revenue from customers		383		383
WES Midstream | United States
Disaggregation of revenue
Revenue from customers		383		383
WES Midstream | Middle East / Africa
Disaggregation of revenue
Revenue from customers		0		0
WES Midstream | Latin America
Disaggregation of revenue
Revenue from customers		0		0
WES Midstream | Other International
Disaggregation of revenue
Revenue from customers		0		0
WES Midstream | Eliminations
Disaggregation of revenue
Revenue from customers		$ 0		$ 0