Reportable Segments Reportable Segments Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 2,560	$ 3,214	$ 5,666	$ 6,643
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(7)	(13)	(22)	(23)
Natural Gas Pipelines
Segment Reporting Information [Line Items]
Revenues	1,565	1,956	3,426	4,148
Natural Gas Pipelines | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(6)	(12)	(20)	(21)
Products Pipelines
Segment Reporting Information [Line Items]
Revenues	345	442	840	866
Terminals
Segment Reporting Information [Line Items]
Revenues	418	506	859	1,014
Terminals | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(1)	(1)	(2)	(2)
CO2
Segment Reporting Information [Line Items]
Revenues	$ 232	$ 310	$ 541	$ 615