Revenues and Accounts Receivable - Disaggregation of Revenue (Details) - Operating Segments - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 3,772	$ 8,698	$ 12,401	$ 17,368
Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	3,055	7,864	10,806	15,710
Supply and Logistics | Crude oil transactions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,928	7,595	10,251	14,532
Supply and Logistics | NGL and other transactions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	127	269	555	1,178
Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	453	551	1,026	1,095
Transportation | Total tariff activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	431	516	969	1,021
Transportation | Crude oil pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	405	494	917	971
Transportation | NGL pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	26	22	52	50
Transportation | Trucking
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	22	35	57	74
Facilities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	264	283	569	563
Facilities | Crude oil, NGL and other terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	176	177	357	349
Facilities | NGL and natural gas processing and fractionation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	80	87	190	175
Facilities | Rail load / unload
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 8	$ 19	$ 22	$ 39