Reportable Segments Reportable Segments Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 3,106	$ 3,429
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(15)	(10)
Natural Gas Pipelines
Segment Reporting Information [Line Items]
Revenues	1,861	2,192
Natural Gas Pipelines | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(14)	(9)
Products Pipelines
Segment Reporting Information [Line Items]
Revenues	495	424
Terminals
Segment Reporting Information [Line Items]
Revenues	441	508
Terminals | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(1)	(1)
CO2
Segment Reporting Information [Line Items]
Revenues	$ 309	$ 305