Revenue Recognition - Disaggregation of revenue (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Disaggregation of revenue
Revenue from customers	$ 3,831	$ 7,556
Marketing and trading
Disaggregation of revenue
Revenue from customers	2	8
United States
Disaggregation of revenue
Revenue from customers	2,619	5,112
United States | Marketing and trading
Disaggregation of revenue
Revenue from customers	2	8
Middle East
Disaggregation of revenue
Revenue from customers	960	1,945
Latin America
Disaggregation of revenue
Revenue from customers	235	461
Other International
Disaggregation of revenue
Revenue from customers	17	38
Corporate & Eliminations
Disaggregation of revenue
Revenue from customers	(227)	(461)
Corporate & Eliminations | United States
Disaggregation of revenue
Revenue from customers	(227)	(461)
Oil and Gas Segment
Disaggregation of revenue
Revenue from customers	2,531	4,985
Oil and Gas Segment | Oil
Disaggregation of revenue
Revenue from customers	2,232	4,422
Oil and Gas Segment | NGL
Disaggregation of revenue
Revenue from customers	175	315
Oil and Gas Segment | Gas
Disaggregation of revenue
Revenue from customers	118	239
Oil and Gas Segment | Other
Disaggregation of revenue
Revenue from customers	6	9
Oil and Gas Segment | United States
Disaggregation of revenue
Revenue from customers	1,491	2,882
Oil and Gas Segment | United States | Oil
Disaggregation of revenue
Revenue from customers	1,334	2,581
Oil and Gas Segment | United States | NGL
Disaggregation of revenue
Revenue from customers	111	200
Oil and Gas Segment | United States | Gas
Disaggregation of revenue
Revenue from customers	42	94
Oil and Gas Segment | United States | Other
Disaggregation of revenue
Revenue from customers	4	7
Oil and Gas Segment | Middle East
Disaggregation of revenue
Revenue from customers	856	1,745
Oil and Gas Segment | Middle East | Oil
Disaggregation of revenue
Revenue from customers	718	1,491
Oil and Gas Segment | Middle East | NGL
Disaggregation of revenue
Revenue from customers	64	115
Oil and Gas Segment | Middle East | Gas
Disaggregation of revenue
Revenue from customers	73	138
Oil and Gas Segment | Middle East | Other
Disaggregation of revenue
Revenue from customers	1	1
Oil and Gas Segment | Latin America
Disaggregation of revenue
Revenue from customers	184	358
Oil and Gas Segment | Latin America | Oil
Disaggregation of revenue
Revenue from customers	180	350
Oil and Gas Segment | Latin America | Gas
Disaggregation of revenue
Revenue from customers	3	7
Oil and Gas Segment | Latin America | Other
Disaggregation of revenue
Revenue from customers	1	1
Chemical Segment
Disaggregation of revenue
Revenue from customers	1,170	2,323
Chemical Segment | United States
Disaggregation of revenue
Revenue from customers	1,102	2,182
Chemical Segment | Latin America
Disaggregation of revenue
Revenue from customers	51	103
Chemical Segment | Other International
Disaggregation of revenue
Revenue from customers	17	38
Midstream Segment
Disaggregation of revenue
Revenue from customers	357	709
Midstream Segment | Gas Processing
Disaggregation of revenue
Revenue from customers	235	468
Midstream Segment | Pipelines
Disaggregation of revenue
Revenue from customers	101	195
Midstream Segment | Power and Other
Disaggregation of revenue
Revenue from customers	19	38
Midstream Segment | United States
Disaggregation of revenue
Revenue from customers	253	509
Midstream Segment | United States | Gas Processing
Disaggregation of revenue
Revenue from customers	131	268
Midstream Segment | United States | Pipelines
Disaggregation of revenue
Revenue from customers	101	195
Midstream Segment | United States | Power and Other
Disaggregation of revenue
Revenue from customers	19	38
Midstream Segment | Middle East
Disaggregation of revenue
Revenue from customers	104	200
Midstream Segment | Middle East | Gas Processing
Disaggregation of revenue
Revenue from customers	$ 104	$ 200