Reportable Segments Table - Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	[1]	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 95,195	$ 98,973		$ 88,413
Intrastate Transportation And Storage [Member]
Segment Reporting Information [Line Items]
Assets	7,215	6,648
Interstate Transportation and Storage [Member]
Segment Reporting Information [Line Items]
Assets	17,341	18,111
Midstream [Member]
Segment Reporting Information [Line Items]
Assets	19,056	20,332
NGL and refined products transportation and services [Member]
Segment Reporting Information [Line Items]
Assets	20,944	19,145
Crude oil transportation and services [Member]
Segment Reporting Information [Line Items]
Assets	19,882	22,933
Investment In Sunoco LP [Member]
Segment Reporting Information [Line Items]
Assets	4,986	5,438
Investment In USAC [Member]
Segment Reporting Information [Line Items]
Assets	3,011	3,730
Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	$ 2,760	$ 2,636

[1] *As adjusted. See Note 1.