Revenues and Accounts Receivable - Disaggregation of Revenue (Details) - Operating Segments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 8,628	$ 8,673
Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,750	7,846
Supply and Logistics | Crude oil transactions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,322	6,936
Supply and Logistics | NGL and other transactions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	428	910
Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	573	544
Transportation | Total tariff activities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	538	505
Transportation | Crude oil pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	512	478
Transportation | NGL pipelines
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	26	27
Transportation | Trucking
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	35	39
Facilities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	305	283
Facilities | Crude oil, NGL and other terminalling and storage
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	182	176
Facilities | NGL and natural gas processing and fractionation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	109	87
Facilities | Rail load / unload
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 14	$ 20