Reportable Segments Reportable Segments Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Assets	$ 71,821	$ 74,157
Corporate and intersegment eliminations
Segment Reporting Information [Line Items]
Assets	2,686	1,966
Natural Gas Pipelines
Segment Reporting Information [Line Items]
Assets	48,522	50,310
Products Pipelines
Segment Reporting Information [Line Items]
Assets	9,216	9,468
Terminals
Segment Reporting Information [Line Items]
Assets	8,808	8,890
CO2
Segment Reporting Information [Line Items]
Assets	$ 2,589	$ 3,523