Reportable Segments Investments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Investments	$ 7,917	$ 7,759
Natural Gas Pipelines | Operating Segments
Segment Reporting Information [Line Items]
Investments	7,262	6,991
Products Pipelines | Operating Segments
Segment Reporting Information [Line Items]
Investments	494	491
Terminals | Operating Segments
Segment Reporting Information [Line Items]
Investments	136	251
CO2 | Operating Segments
Segment Reporting Information [Line Items]
Investments	$ 25	$ 26