Revenues and Accounts Receivable - Segment Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 8,269	$ 8,375
Transportation
Disaggregation of Revenue [Line Items]
Total revenues	187	197
Facilities
Disaggregation of Revenue [Line Items]
Total revenues	175	156
Supply and Logistics
Disaggregation of Revenue [Line Items]
Total revenues	7,907	8,022
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	8,628	8,673
Total revenues	8,800	8,877
Operating Segments | Transportation
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	573	544
Total revenues	579	556
Operating Segments | Facilities
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	305	283
Total revenues	313	299
Operating Segments | Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	7,750	7,846
Total revenues	7,908	8,022
Intersegment
Disaggregation of Revenue [Line Items]
Total revenues	(531)	(502)
Intersegment | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	(282)	(253)
Intersegment | Facilities
Disaggregation of Revenue [Line Items]
Total revenues	(138)	(143)
Intersegment | Supply and Logistics
Disaggregation of Revenue [Line Items]
Total revenues	(1)
Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues	172	204
Other | Operating Segments | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	6	12
Other | Operating Segments | Facilities
Disaggregation of Revenue [Line Items]
Total revenues	8	16
Other | Operating Segments | Supply and Logistics
Disaggregation of Revenue [Line Items]
Total revenues	$ 158	$ 176